Date: Thu, 14 Nov 2002 23:02:52 -0000
From: John Robinson
Subject: please advise on color conversion
I believe on my desktop that Photoshop 7's color conversion from rgb to cmyk, using Adobe RGB 1998 to SWOP . . . is awful. Blue skies go purple. Red is dead. I know, I know about the color spaces and all, but it is still awful. So am I stuck sending my files out to be converted when color is critical, or is their an available algorithym(file) available that will save me some cash. Or do I have to spend some cash to get the file?Would be nice to not have to do as much curve work, or have more color info to work with.
Or am I just plain naive.
John Robinson
Date: Thu, 14 Nov 2002 18:06:22 -0700
From: "Andrew Rodney
Subject: Re: please advise on color conversion
John Robinson wrote:> I believe on my desktop that Photoshop 7's color conversion from rgb to cmyk,
> using Adobe RGB 1998 to SWOP . . . is awful.You1re doing something wrong! It may be the Adobe RGB data isn1t really the right tag for the file (I have no way to know how you1re getting data into Photoshop). At a recent CMS shootout at Seybold, of the 6 custom profile packages used to produce CMYK to a Creo Proof, the Photoshop SWOP V2 profile was the best (Shocking but that1s what happened). Thomas Knoll created his own software to build profiles and the SWOP V2 when used correctly (and sent to a device that really does mimic TR001 SWOP) should produce a very, very good print.
Now it's possible you're sending CMYK to a device that in no way behaves as TR001 SWOP and naturally, using the PS profile will produce poor results (the soft proof in Photoshop should still look fine, it's the device isn't behaving as the profile expects). You'll need a custom ICC profile or get the shop to supply you with settings that better mimic what they are actually printing to.
The Photoshop SWOP profile is excellent but like any color targeting, if you target the data to a device and that device isn't responding as you assume, you'll get poor output.
Andrew Rodney
Date: Fri, 15 Nov 2002 01:07:53 -0000
From: Stephen Marsh
Subject: Re: please advise on color conversion
> I believe on my desktop that Photoshop 7's color conversion from rgb to cmyk,
> using Adobe RGB 1998 to SWOP . . . is awful. Blue skies go purple. Red is dead.
> I know, I know about the color spaces and all, but it is still awful. So am I stuck
> sending my files out to be converted when color is critical, or is their an
> available algorithm(file) available that will save me some cash. Or do I have to
> spend some cash to get the file?
>
> Would be nice to not have to do as much curve work, or have more color info
> to work with.John, can you describe exactly the name of the setting you are using?
Is this Custom CMYK (similar to the old legacy Photoshop CMYK engine)?
Are you using the v2 profiles from Adobe? If so the US Web Coated (SWOP) v2 or whatever it is called is really quite good (based on TR001 measurements).
Chromix Profile Central also has a full range of CMYK SWOP TR001 profiles, which offer more flexible options when it comes to TAC and K generation (Adobe only offer one sep method). http://www.chromix.com (the profile central page is down though so you will have to get the profiles off someone )
When it comes to problem out of gamut colours - some conversions may never do the job exactly, and post sep edits are required...I might also go one step further and boldly state that the more the original is out of gamut - the more post separation work will be required to do justice to the original larger gamut image in the new smaller space.
Stephen Marsh.
Date: Thu, 14 Nov 2002 21:50:51 -0500
From: Lee Collins
Subject: Re: please advise on color conversion
I find that if the GCR is on medium and we do color corrections in RGB, when
we change the mode to CMYK we get a flat godawful color image. I'm in teaching, not in production so I may have offered a naive answer, but we get much better images in the changeover with light GCR setting to start.Lee Collins
Date: Thu, 14 Nov 2002 20:20:22 -0700
From: Chris Murphy
Subject: Re: please advise on color conversion
On Thursday, November 14, 2002, at 06:06 PM, Andrew Rodney wrote:
> YouÕre doing something wrong! It may be the Adobe RGB data isnÕt
> really the
> right tag for the file (I have no way to know how youÕre getting data
> into
> Photoshop). At a recent CMS shootout at Seybold, of the 6 custom
> profile
> packages used to produce CMYK to a Creo Proof, the Photoshop SWOP V2 profile
> was the best (Shocking but thatÕs what happened).Actually it was the U.S. Sheetfed Coated v2 profile that came out best.
I didn't rate the U.S. Web Coated (SWOP) v2 profile, but I did use it in the test. It produced images that were a little on the dark side as a result of it not adequately compensating for the higher dot gain of a 175lpi printing process. However, if printing under SWOP-like conditions, the SWOP profile provided with Photoshop is quite a good profile.Chris Murphy
Color Remedies (tm)
Boulder, CO
303-415-9932
Date: Thu, 14 Nov 2002 22:40:03 -0500
From: Jim Rich
Subject: Re: please advise on color conversion
Lee Collins wrote:> I find that if the GCR is on medium and we do color corrections in RGB, when
> we change the mode to CMYK we get a flat godawful color image. I'm in
> teaching, not in production so I may have offered a naive answer, but we get
> much better images in the changeover with light GCR setting to start.Lee,
How are you proofing the cmyk image?
Are you using an analog proof such as a Matchprint?
Or a digital proof?
Do you know if your proofing system in control?
And if you think it is, can you verify it?
I personally like and have suggested for years to use the light k with gcr, but the color appearance of medium and light color separations are often the same.Jim Rich
Date: Fri, 15 Nov 2002 05:39:33 -0000
From: John Robinson
Subject: Re: please advise on rgb to cmyk conversion
I'll explain some further.G4/500/dual/1gigRAM/OSX.2.2
On my desktop in Photoshop 7, if I use the Adobe RGB 1998, to SWOP . . . conversion, I can take my INFO pallet and measure the resulting converted CMYK sky (for instance), and there is a lot of red where there should not be. This is the way it has always been for me for several years. And I could be doing it all wrong. So I always have to take images into Curves (thanks to Lord Dan) and remove most from the sky to look natural when printed, especially on uncoated stock.
If I send it to a seperation house, or to our scanner where they run it through some LinoColor process conversion (I am not sure) the blues are almost as true as the RGB file. It is a wonderful conversion. I can't complain. But I will.
I was told the software to do this is expensive, so I have never questioned it, but man, I am tired of getting a crappy conversion in what is suppose to be a professional application. Again, maybe I am not doing it correctly.
I can't believe it is only using another SWOP selection from Photoshop 7's collection, BUT I am OPEN to any suggestion, please.
John Robinson
Date: Fri, 15 Nov 2002 09:47:51 -0000
From: Stephen Marsh
Subject: Re: please advise on rgb to cmyk conversion
Hi John, I'll presume that you were responding to my request for more info below - but I was after the EXACT profile name or setting combination that you are converting with. And while I am at it, what rendering intent and or BPC options or colour engine etc (all the exact and specific separation variables from both colour settings or convert to profile dialog boxes). Then if you can describe the steps in the conversion (image/mode/cmyk or image/mode/convert to profile).This may help resolve part of your issues. But as I mentioned earlier, a conversion can only ever take you so far - and when dealing with well known CMYK problem hues/tones there is only so much you can do before you 'spin your wheels'.
> I'll explain some further.
>
> G4/500/dual/1gigRAM/OSX.2.2
> On my desktop in Photoshop 7, if I use the Adobe RGB 1998, to SWOP . . .Which is why I originally asked:
>> John, can you describe exactly the name of the setting you are
>> using?
>>
>> Is this Custom CMYK (similar to the old legacy Photoshop CMYK
>> engine)?
>>
>> Are you using the v2 profiles from Adobe? If so the US Web
>> Coated (SWOP) v2 or whatever it is called is really quite good
>> (based on TR001 measurements).> Again, maybe I am not doing it correctly.
Not sure at this point until settings and workflow are known.
> I can't believe it is only using another SWOP selection from Photoshop 7's
> collection, BUT I am OPEN to any suggestion, please.So you may be using the v2 profile after all? I would not choose the V2 SWOP Coated profile for uncoated work (which you mentioned as a problem), do you use Custom CMYK when doing this type of output?
Stephen Marsh.
Date: Fri, 15 Nov 2002 09:06:16 -0500
From: David Ridderhof
Subject: Re: please advise on rgb to cmyk conversion
I am having sort of the same problem as John, specifically in the warmer hues which include fleshtones (my main concern). They consistently gain magenta when proofing after converting to cmyk. I scan my images which are embedded with the scanners profile, convert to Adobe rgb 1998 when opening in Photoshop, and they look fine on screen. The rgb numbers (ex.fleshtones- r=147, g=95, b=82) seem fine and look right on screen, but the cmyk readings in the info palette show magenta above yellow consistently (c=25, m=64, y=60, k=9). I use a number of cmyk conversions, from custom setups based on printers supplied specs, to the canned ones such as US Swop Coated v2. Same thing happens. The other hues seem fine.When I convert to cmyk, the soft proof doesn't visually change (except out of gamut colors). But the cmyk numbers seem out of whack, and my proofs reflect it. (Creo iProof, which has a rip for cmyk using devicelink profiles). I have to almost transpose the yellow and magenta in some cases to get a decent fleshtone, which throws my soft proof all to hell.
I suspect it may be my monitor, which is almost 7 years old, but the issue seems to only be with the above mentioned hues and I dont understand the way the numbers are displaying.
Any thoughts about my problem are welcome.
David Ridderhof
Date: Fri, 15 Nov 2002 16:12:22 -0000
From: John Robinson
Subject: Re: rgb to cmyk conversion
Thanks for responding:I do not use profiling. I want the numbers correct first. If I could measure after the conversion to CMYK, and the blues were not too hot, then I would not be asking the group.
__________________For instance I have a RGB colorful swirling background of Blues to dark blues most prominent, and I convert this RGB original file (source is a royalty free CD) to CMYK in Photoshop 7, I get a mostly gray blues to purple background. P7.
I do not rely on any profiling. Maybe I should, but if my numbers are accurate the press proof can't get much more off with the 20% gain as deault. I rely on the INFO pallet. I MEASURE the overall reds in the CMYK blue sky. They are deceptive on a monitor. If the reds measure hot, they ain't getting any cooler on press.
My color settings are:
Working Spaces:
RGB: Adobe RGB 1998
CMYK: US Web Coated (SWOP) v2Color Management: OFF
Conversion Options: Adobe (ACE)
Intent: Relative Colormetric
Black Point Compensation: ONDesaturate Monitor Colors 20%: OFF
Blend RGB Colors using Gama 1% OFF
_______________If I take the same RGB image give it to our PrePress people down stairs who open the rgb file in LinoColor/Heilge something. POOF. Their conversion looks great, close to truly blue blues. Not red/purple blues in my conversion.
They told me Lino first converts to LAB. Then CMYK.
By the way, they say LinoColor is not available anymore so they are looking at other software.
________________
Should the process be RGB to LAB to CMYK?
Or am I expecting too much from Photoshop?
Do I always need to send rgb files out for conversion if color is critical?
_________________I think I know why if the production environment is a closed circuit why many use profiles. Am I wrong to not care about profiles as long as the INFO pallet gives me accurate readings and I allow for dot gain?
John Robinson
Date: Fri, 15 Nov 2002 13:36:10 -0700
From: Andrew Rodney
Subject: Re: Re: rgb to cmyk conversion
John Robinson wrote:>I do not use profiling.
IF you are using Photoshop 5-7 you're using profiles. That's the only way Photoshop conducts colorspace conversions (even when you go into the build it Sep settings).
Andrew Rodney
Date: Fri, 15 Nov 2002 20:46:27 -0000
From: John Robinson
Subject: Re: rgb to cmyk conversion
> I do not use profiling.Duh. I was corrected off list. If I am using Photoshop 5-7, I am using profiles.
I will see if I can obtain the LinoColor/Helg. profiles Prepress uses, and re[port my results.
Thank you.
John Robinson
Date: Fri, 15 Nov 2002 17:34:56 -0500
From: Jim Rich
Subject: Re: Re: rgb to cmyk conversion
John,It sounds like you need to make a color correction before converting your RGB image to CMYK. Or of course you could correct the image after you convert to CMYK, but there is less flexibility in doing that.
The correction you might be after is something like minus magenta in blues and or minus magenta in cyan colors. I might suggest using the Selective color tool in Photoshop for that. How much minus magenta depends on the look and feel you want in your color separation. Of course you would go by the numbers to get the visual result you want.
You could do this either one image at a time, create an action that applies those types of color corrections or edit a cmyk profile to reflect those corrections.
It also sounds like the guys who use Linocolor either have their profiles tuned well or they just make the right color corrections and then they give you back the image.
I personally do not find a need to go to LAB. I have enough experience to do most all color corrections in RGB or even in CMYK. But mileage will vary on that one.
As for setting your expectations, Photoshop will create very good color separations. If you start with good images you are well on your way. If you start with 100% garbage then you might end up with 50% garbage and 50% a better result, after lot of work.
If you are expecting magic to get a good color reproduction by just making a mode change and with out knowing how to control highlights, midtone shadows, neutrals and selective color areas by going by the numbers, then you might want to re-evaluate your situation.
To get the best results you need to understand how to control the variables of a color image (such as netural gray, image contrast and the selective colors) and use Photoshop tools to do that.
My .02.
Jim Rich
Date: Fri, 15 Nov 2002 21:19:46 EST
From: Dan Margulis
Subject: Re: rgb to cmyk conversion
John Robinson writes,>>If I take the same RGB image give it to our PrePress people down stairs who open the rgb file in LinoColor/Heilge something. POOF. Their conversion looks great, close to truly blue blues. Not red/purple blues in my conversion.>>
This is just a question of whether you'd rather be hung or take poison. There's no overall solution to the problem that CMYK has a very deficient range of blues in comparison to RGB. No conversion method, no profile, is going to do the right thing all the time.
As you say, the "SWOP Web Coated v.2" profile makes blues purple in comparison to the traditional Photoshop engine. A pure blue in Adobe RGB, 0r0g255b, converts to 86c76m with the SWOP profile but a much bluer 100c78m in traditional Photoshop. A less brilliant blue, 50r50g200b, is an even purpler 81c76m in the profile but 91c71m in traditional Photoshop.
So, the traditional Photoshop way is better--if you happen to have a picture that features deep blue skies. If the picture is of a lake where the blue isn't that intense, the SWOP profile should be better. And if it's a picture of the New York Rangers or some other sports team that wears bright blue uniforms, *both* of these profiles suck in a big way. Notice how little difference there is in the two sets of CMYK blues shown above, in comparison to the huge difference when it's still in Adobe RGB.
So, if you were to convert the New York Rangers picture using either of the two methods you'd have to spend time afterwards building in the detail that the conversion lost. And that's the whole key. No matter what conversion method you use you'll be stuck doing some CMYK correction afterwards on certain images.
You seem to think that the SWOP profile is a bad one. So it is--for the particular pictures you are discussing. If you use Linocolor's supplied profiles you'll do better on those pictures but worse on others. Personally, I think that purplish blues are the most flexible way of handling the conversion, so I'd live with this problem rather than trade it in for a different one.
Dan Margulis
Date: Fri, 15 Nov 2002 21:01:17 EST
From: Dan Margulis
Subject: Re: Re: please advise on rgb to cmyk conversion
David Ridderhof writes,>> I scan my images which are embedded with the scanners profile, convert to Adobe rgb 1998 when opening in Photoshop, and they look fine on screen. The rgb numbers (ex.fleshtones- r=147, g=95, b=82) seem fine and look right on screen, but the cmyk readings in the info palette show magenta above yellow consistently (c=25, m=64, y=60, k=9). >>
147r95g82b is a brick red in Adobe RGB and even grayer in other RGBs. It's not particularly close to being a valid fleshtone. The contaminating colors (cyan plus black) are more than twice as high as they should be. Convert that to CMYK, and it will indeed be too muddy-red. The proofs you are seeing are correct.
If that color is appearing to be a valid fleshtone on your monitor, it's a monitor calibration issue.
Dan Margulis
Date: Sat, 16 Nov 2002 02:56:39 -0000
From: John Robinson
Subject: Re: rgb to cmyk conversion
Jim Rich wrote:> If you are expecting magic to get a good color reproduction by just making a
> mode change and with out knowing how to control highlights, midtone shadows,
> neutrals and selective color areas by going by the numbers, then you might
> want to re-evaluate your situation.Jim, I set white point, black point, and neutrals, on a naturally lit scene. If I do it correctly I get no more than 300% in shadows (and overall), and minimum 5/3/3/0 in whites. Sometimes i use channel swaps and curve manipulation as needed. Nothing I think is oversaturated after that.
Talking with my people they say, NO manipulation, like curves or selecting certain areas to improve. It is a conversion.
I have converted many rgb files in the last several years in Photoshop 2.5 to 7. I have used Adobe RGB 1998 to SWOP of one type or another. The converted numbers don't lie to me. What I see on the monitor is what I am measuring: There is red in what is suppose to be gorgeous blue skies. I am told over and over that I need to see what will be printed on a calibrated monitor. If I see red and measure red. What do I need a calibrated monitor for? The press will print the red. So I have to go into Curves (or one of several selective methods) and remove the red everytime.
I am curious, with all the color experts sharing the list, do they use Photoshop to convert RGB to CMYK? Or is that a naive query?
John Robinson
Date: Sat, 16 Nov 2002 15:31:14 -0500
From: Jim Rich
Subject: Re: Re: rgb to cmyk conversion
John,If your colleagues are just doing a conversion then why don1t you get their profile from Linocolor and use it in Photoshop. This should help.
> What do I need a calibrated monitor for?
Consider these ideas.
I am sure most all color experts will agree, going by the numbers is one reasonable way to insure that the color will come out right before printing a proof. The down side to that approach is that you have to know what the numbers mean, which can entail a long learning curve as well as expense and if you are a business you have large salaries to pay.
Next Consider this. It has been a proven fact for at least ten years now that if you get your monitor to display an image that is visually close to the input image and output proofs you are going to have less wasted proofs (and money).
So then, at least to me and a few others on this list, it is obvious that if you learn how to go by the numbers and have your monitor /imaging system calibrated you will have a productive color reproduction system where you stand a real good chance of using your monitor as a soft-proof to estimate what the image will look like before printing it to a proof. This is what a properly setup color management system will allow you to do. In that process if you measure key image areas you verify them from your experiences with your system if the numbers are going to work. Combining these two approaches (going-by-the -numbers and icc profiles) is how to get your color reproduction right the first time you create a color separation.
I am curious, with all the color experts sharing the list, do they use > Photoshop to convert RGB to CMYK? Or is that a naive query?
As for who uses Photoshop to convert from RGB to CMYK, my guess and it is a guess is that a majority of Photoshop users use the base Color settings or a few variations on them. As for the experts my guess is that some use profiles and other use the base Color Settings or a variation on them. Then they roll up their sleeves and do heavy lifting to get exactly the tones and colors they want.
Another question to consider is what does it take to set up a calibrated system?
I am not looking for a fight or to send a religious message on this topic, since there are a lot of opinions on how to get calibrated. But think about these two options.
1-Don1t use ICC profiles.
Use a closed loop approach and run around your shop, lab or business calibrating your scanner, printer and monitor.
If you only have one scanner, printer and monitor then that might be a good cost effective solution. If find it can be.
But suppose a business has 10 or more computers, three scanners and four printers. It is possible to use closed loop methods to calibrate all of that equipment and get the input and output and monitors to visually agree. The downside of that is that it might take someone a week or more to get it set up. Then of course what it something changes they have to spend almost that much time getting things back in calibration.
2- Use ICC profiles. Use profiling tools to create profiles for your equipment.
For a single user business this works quite easily, but it can be cost prohibitive for the tools.
In the business model that has say has 10 or more computers, three scanners and four printers. This is where profiles can be quite effective to get input and output devices under control. The benefit is that there is less fiddling with devices and wondering why the color comes out wrong.
Profiles are not prefect and color can still come out looking bad especially if you don1t take the time to learn how to use the technology, but once you do that, the effort translates into saved time and money as I pointed out about have the monitor matching the proofs.
I am comfortable using either calibration approach, but I have found that using profiles is just easier for me and my clients.
Jim Rich
Date: Mon, 18 Nov 2002 07:16:11 -0500
From: John Rawlins
Subject: Re: rgb to cmyk conversion
Jim Rich wrote:>Profiles are not perfect and color can still come out looking bad especially
>if you don1t take the time to learn how to use the technology, but once you
>do that, the effort translates into saved time and money as I pointed out
>about have the monitor matching the proofs.Jim
Excellent points. Very few realize the importance of incorporating the by the numbers approach into todays workflow environments. Profiles are there to help you not save you. If you are clueless on your RGB or converted CMYK values you are going to burn up a lot of valuable time and proof materials getting to an acceptable result.
John Rawlins
Date: Mon, 18 Nov 2002 19:21:33 -0000
From: John Robinson
Subject: a revelation
I was first told "no manipulation" following the scan.I watched today as they converted. They use Adobe RGB 1998 & US SWOP v2, just as I do. The difference is using LinoColor after the scan. Of course they manipulate. The menus in LinoColor seem more sophisticated than just Curves in Photoshop. The menu's seem to be able to target areas of color and make subtle adjustments quicker and easier than in Photoshop 7, and perhaps that's the reason my conversions don't compare. Guess we paid for more sophisticated targeting correction ability with LinoColor.
Just wish Photoshop could carry the same color targeting menus.
John Robinson
Date: Mon, 18 Nov 2002 15:03:18 -0500
From: Andrew Darlow
Subject: Re: Re: rgb to cmyk conversion
Hello:I'm curious if there are other ways to pull color out of an RGB file to create a neutral RGB(looks B&W) after making my contrast adjustments in RGB to optimize the look of a file before converting. I like the overall effect of just converting to grayscale and then back to RGB after getting an ideal looking RGB file. However, I understand from someone's online post that this might do some damage to the gradients(especially in PS7 for some reason) compared with keeping it in RGB and doing something analogous to desaturate.
I'd prefer not to use the Hue/Saturation technique of pulling out all saturation because it alters the visual look of some of the adjustments I've made prior to the Hue/Saturation edit, compared with the way it looks if I just convert to grayscale.
I like the look of the L channel in Lab, but the skintones become a bit washed out. I'm thinking that this approach, with a curves adjustment is the way to go.
Any other info is welcome.
All the best!
Andrew Darlow
Date: Mon, 18 Nov 2002 16:41:23 -0500
From: Jim Rich
Subject: Re: a revelation
John Robinson wrote:> Of course they manipulate. The menus in LinoColor seem more
> sophisticated than just Curves in Photoshop. The menu's seem to be
> able to target areas of color and make subtle adjustments quicker and
> easier than in Photoshop 7, and perhaps that's the reason my
> conversions don't compare. Guess we paid for more sophisticated
> targeting correction ability with LinoColor.John,
No one tool is perfect and it sounds to me that grass is greener.
I have used LinoColor off and on for years and while it has interesting color tools so does Photoshop.
More can be better, but I have to ask what type of tools do you want for targeting in Photoshop? More sampler points? More ways to threshold highlights and shadows. More user defined neutral shadow only adjustments?
Jim Rich
Date: Mon, 18 Nov 2002 15:55:16 -0800
From: Rick Gordon
Subject: Re: Re: rgb to cmyk conversion
A favorite approach of mine is to use an action that I've set up, which creates a layer set whose first layer is a curve adjustment layer with preset anchor points at 64, 128, and 192 on each of the 3 color channels. Above that, it puts a hue/saturation adjustment layer with saturation pulled all the way to -100. The top adjustment layer is a curve set to luminosity mode.Then after creating all of the layers, it selects and opens the color curve layer for editing. I edit each of the 3 color channels as necessary; sometimes making an adjustment and on the composite RGB channel can also be useful.
Then, if necessary, I adjust the luminosity curve, flatten, and convert to grayscale mode.
The other useful -- and frequently described -- approach is using channel mixers, but I find that I use the procedure described above more.
Rick Gordon
------------------
On 11/18/02 at 3:03 PM -0500, Andrew Darlow wrote:
>I'm curious if there are other ways to pull color out of an RGB file
>to create a neutral RGB(looks B&W) after making my contrast
>adjustments in RGB to optimize the look of a file before converting.
>I like the overall effect of just converting to grayscale and then
>back to RGB after getting an ideal looking RGB file. However, I
>understand from someone's online post that this might do some damage
>to the gradients(especially in PS7 for some reason) compared with
>keeping it in RGB and doing something analogous to desaturate.___________________________________________________
RICK GORDON
EMERALD VALLEY GRAPHICS AND CONSULTING
___________________________________________________PHONE: 415-663-8652
WWW: http://www.shelterpub.com
Date: Mon, 18 Nov 2002 19:13:34 -0800
From: Lee Varis
Subject: Re: Re: rgb to cmyk conversion
Andrew Darlow wrote:> I'm curious if there are other ways to pull color out of an RGB file
> to create a neutral RGB (looks B/W) after making my contrast
> adjustments in RGB to optimize the look of a file before converting.Another method that hasn't been mentioned is to "split" the channels of the RGB file. Go to the upper right corner of the Channels palette & click on the option drop down (little triangle thingy) select "split channels" and the RGB document will break apart into 3 - grayscale documents. You can then drag one document onto the other with the Move Tool and then use the opacity slider in the layers palette to blend the "layers" together. What makes this approach interesting is when you utilize layer apply modes like darken, lighten or overlay in combination with layer masks to control tonal rendition of the "colors" of the RGB now rendered as gray "layers" - lots of interesting possibilities.
regards,
Lee Varis
http://www.varis.com
888-964-0024
Date: Tue, 19 Nov 2002 10:50:08 -0600
From: David.Clark
Subject: Re: a revelation
John Robinson,Look at the Color Correction Pro filter from www.theimagingfactory.com
It targets selective color effectively in Photoshop, and it works well with the Kodak profile editor.
David Clark
Date: Fri, 22 Nov 2002 12:44:09 -0600
From: "Maris V. Lidaka Sr."
Subject: Re: please advise on color conversion
Any particular suggestions as to the best profile for those of us who do desktop inkjet printing? I am not satisfied with the PS7 default of U.S. Web Coated (SWOP)v2
Maris
Date: Fri, 22 Nov 2002 14:36:21 -0800
From: "Penelle, Philippe G. (US - Charleston)"
Subject: RE: please advise on color conversion
Maris--in most cases I don't think that you should send CMYK data to desktop inkjet printers but rather send RGB data and let the printer's internal color management software do the separation. If you capture the image with RGB device and edit the image in CMYK, reasonable separation profile might be SWOP 2 with light GCR, something around or slightly less than 300% total ink limit and around 85% limit on black ink. That should give better separation than PS7 default. But then when you're finished with CMYK editing, it's probably better to go back to RGB (maybe through LAB?).Regards,
Philippe
Date: Fri, 22 Nov 2002 17:27:48 -0600
From: Maris V. Lidaka Sr
Subject: Re: please advise on color conversion
Thank you, Philippe. I should have made myself clear - I don't send CMYK to the inkjet. I send RGB but prefer to adjust in CMYK and I have had problems in color consistency in converting each way, more so back from CMYK to RGB. Your suggestion to convert to LAB first is good, and often do so routinely to sharpen, then return to RGB for print.Maris
Date: Fri, 22 Nov 2002 15:35:24 -0700
From: Chris Murphy
Subject: Re: please advise on color conversion
Maris V. Lidaka Sr. wrote:> Any particular suggestions as to the best profile for those of us who do
> desktop inkjet printing? I am not satisfied with the PS7 default of
> U.S. Web Coated (SWOP)v2That's because your inkjet printer isn't a Web Coated (SWOP) v2 printer, so it doesn't make sense to use that profile. You need to use a profile for your inkjet printer. If it's non-PostScript, this means you will be converting your images to RGB at print time using either custom or manufacturer supplied profile for your printer and media.
Chris Murphy
Color Remedies (tm)
Boulder, CO
www.colorremedies.com
Date: Fri, 22 Nov 2002 16:33:06 -0700
From: Andrew Rodney
Subject: Re: Re: Proof color in Photoshop Info palette
John Robinson wrote:> Are you saying if you color correct in RGB, and if
> you are viewing in CMYK, that you can leave the conversion to the RIP
> and know exactly will print on press?No not really. If you are trying to use the RIP/Ink jet to simulate another process (the press) then you will need to start with CMYK data and convert to a different form of CMYK (or even RGB) to send to the printer. The printer is then set, using two ICC profiles to simulate device A onto device B.
If all you want is a nice print from your ink jet, there is no reason to convert to CMYK (and plenty of reasons not to).
Andrew Rodney
Date: Fri, 22 Nov 2002 23:39:43 -0000
From: Stephen Marsh
Subject: Re: please advise on color conversion
"Penelle, Philippe G." wrote:
> Maris--in most cases I don't think that you should send CMYK data to desktop
> inkjet printers but rather send RGB data and let the printer's internal
> color management software do the separation. If you capture the image with
> RGB device and edit the image in CMYK, reasonable separation profile might
> be SWOP 2 with light GCR, something around or slightly less than 300% total
> ink limit and around 85% limit on black ink. That should give better
> separation than PS7 default. But then when you're finished with CMYK
> editing, it's probably better to go back to RGB (maybe through LAB?).Philippe, I agree with your general points above.
FYI, the SWOP v2 profile cant have the GCR or TAC altered, without an editor...then it is no longer the 'legal' Adobe profile.
Chromix does offer a set of TR001 data with different UCR/GCR and TAC though.
But your point is taken, a lighter K generation method than the Adobe v2 profile can be very helpful for CMYK colour correction.
I agree - unless you have a PostScript RIP on the inkjet, feeding the inkjet the flavour of RGB it requies is the best step...as feeding CMYK to a non PS device is not a good idea.
As for LAB, there is no need to go to ICC LAB mode first - as Photoshop will use a better form of LAB for the conversion behind the scenes when using the old colour engine or ICC profiles with newer versions (CIE LAB or CIE XYZ in the profiles connection space).
Regards,
Stephen Marsh.
Date: Fri, 22 Nov 2002 18:18:33 -0600
From: "Maris V. Lidaka Sr."
Subject: Re: please advise on color conversion
Huh? My inkjet printer (Epson C80) clearly doesn't have a profile usable in PS to convert from RGB to CMYK and back to RGB for image color-correction purposes (as opposed to its internal RGB to CMYK conversion in the printing process).But perhaps I should take a step back - I may be making a wrong assumption.
Does the CMYK specification in "Working Spaces" on the Color Settings panel in PS7 have anything to do with the conversion from RGB to CMYK and back while working on the image? If not, my question is moot and my quest fruitless.
Maris
Date: Fri, 22 Nov 2002 20:42:19 -0500 (Eastern Standard Time)
From: Michael Demyan
Subject: Re: please advise on color conversion
Maris:Your inkjet printer requires RGB files to print properly. The profile was saved on your computer when you installed the printer drivers.
When you select File>Print go to the Print Space box at the bottom of the dialog box and in the Profile drop down select "Printer Color Management". This instructs Photoshop to allow the printer to control the color according to the manufacturer's profile. All prosumer inkjets require RGB files.
Once you convert a file to CMYK you change the color information to fit into a smaller gamut.
Therefore you loose some of the vibrancy that you see on screen.
You can convert the file back to RGB -BUT - you will never reclaim the colors or full RGB gamut.
BE-AWARE! If you "SAVE" the file on top of the original - you now have an RGB file with a CMYK gamut.
Mike Demyan
http://home.ptd.net/~mdemyan
Date: Fri, 22 Nov 2002 20:48:21 -0500 (Eastern Standard Time)
From: "Michael Demyan"
Subject: Re: re: light inks gamut
The additional inks are for one and only one purpose:To make the image look more like a photograph.
Its not a printing press.
The manufacturer's printer profile takes an RGB file and attempts to print the BEST IMAGE YOU EVER SAW.
Date: Fri, 22 Nov 2002 20:48:59 -0500
From: "Jerry L. P'Simer
Subject: Re: Re: rgb to cmyk conversion
Lee Varis wrote:> Another method that hasn't been mentioned is to "split" the channels of
> the RGB file ? go to the upper right corner of the Channels palette &
> click on the option drop down (little triangle thingy) select "split
> channels" and the RGB document will break apart into 3 - grayscale
> documents. You can then drag one document onto the other with the Move
> Tool and then use the opacity slider in the layers palette to blend the
> "layers" together. What makes this approach interesting is when you
> utilize layer apply modes like darken, lighten or overlay in
> combination with layer masks to control tonal rendition of the "colors"
> of the RGB now rendered as gray "layers" - lots of interesting
> possibilities.Hello Lee,
I have been away from my e-mail for a few days so this is kind of a late post on this subject. I find this technique to be very interesting indeed. Before the days of photoshop I used to use a similar approach on a Scitex work station when the stations were still running on the old HP platform. There really was not a good method of converting from CMYK to grayscale. (necessity is truly the mother of invention) These work stations only used the CMYK color space. To accomplish what you describe above was very cumbersome as each of the cmy plates had to be blended with the k plate first before blending them together to create a decent grayscale image. I wrote a script to take care of the initial blending and then would custom blend from there depending on the goals for the individual image. The whole process could take more than an hour, but the results were worth it (And at that point in time clients were willing to pay for this as well).I just spent an hour or so using the methods that you describe above and it is very interesting what can be accomplished this way. It reminds me very much of the kind of results that could be achieved using my earlier methods (with much greater power than Scitex) which I have not thought of in many years. With PS's capabilities and blending modes there are many things that can be achieved this way that would be very difficult to achieve otherwise. It never occurred to me to try this in PS because there are many good ways to create grayscale images in PS. That is what I like about PS in general because there are many many methods that can be employed to tackle almost any problem encountered. Thank you Lee for your post.
Sincerely,
Jerry P'Simer
Date: Fri, 22 Nov 2002 20:47:12 -0700
From: Andrew Rodney
Subject: Re: please advise on color conversion
Maris Lidaka wrote:> Does the CMYK specification in "Working Spaces" on the Color Settings panel
> in PS7 have anything to do with the conversion from RGB to CMYK and back
> while working on the image? If not, my question is moot and my quest
> fruitless.NOT to the ink jet. ONLY to a device where you actually used the ICC profile to do a mode change.
Andrew Rodney
Date: Fri, 22 Nov 2002 23:06:12 -0600
From: "Maris V. Lidaka Sr."
Subject: Re: please advise on color conversion
Mike,I'm well aware my and other inkjet printers expect RGB and that my C80 came with a profile *for printing purposes*, which I use as per your description unless I am using a custom printer profile - I have purchased some from CDTobie with good success.
The point of my follow-up question was that PS7 does not use my Epson profile nor for that matter CDTobie's profiles when I switch back & forth between RGB and CMYK *while working on the image, correcting it* - the Epson or CDTobie profiles only come into play when I'm done and either proof the image or print the image using those profiles [see -I know whereof I speak ;-)].
My question was does PS7 use the CMYK specification that I select on the Color Settings panel during the time I am adjusting the image should I elect [foolishly ;-)] to convert from RGB to CMYK to color-correct a person's face, and back to RGB so I can print the face, or does PS7 use some other profile or methodology for that conversion?
Maris
Date: Sat, 23 Nov 2002 05:25:58 -0000
From: Stephen Marsh
Subject: Re: please advise on color conversion
Hi Maris, On the RGB/CMYK & inkjet thing, I was confident you knew better from your posts on this and other lists - but many times a reply on this list may be aimed at the 'lurking masses' more so than for the originator of the post...which can sidetrack the original post a bit.<g>> My question was does PS7 use the CMYK specification that I select on the
> Color Settings panel during the time I am adjusting the image should I elect
> [foolishly ;-)] to convert from RGB to CMYK to color-correct a person's
> face, and back to RGB so I can print the face, or does PS7 use some other
> profile or methodology for that conversion?Presuming Photoshop 6 or 7 with default colour setting type behaviour...
Your RGB file will be tagged and understood. If you choose image/mode/cmyk then the conversion will use the settings in colour settings for the cmyk workspace and the render intent and BPC and dither etc. Once in CMYK the new tag is active and understood. If you use image/mode/c2p - then whatever profile and other options you select will be used instead of the colour settings default. When going out of CMYK back to RGB or other modes - then the same sort of thing goes on.
It all depends on your settings and workflow - but generally speaking if the tag is honoured then that is used, if not then the colour settings work space and other settings for that files mode will be applied as default to the file instead.
Why do you have concerns that the profiles that you are converting to are not being honoured when going back to another space? Have you turned off CM in v6 or higher, or do you preserve and show warnings etc?
Does this help?
Stephen Marsh.
Date: Sat, 23 Nov 2002 02:18:16 -0600
From: Maris Lidaka
Subject: Re: Re: please advise on color conversion
Hi Stephen,
Perhaps my earlier posts weren't phrased clearly enough either (and words are a primary part of my primary profession - don't "Guess My Line" though, please <g>)
It is crystal clear now - thank you once again.
I'm using PS 7.01 with CM on, preserve and show warnings and the whole bundle. I learned 'color by the numbers' though from a book by a gentleman called Dan Margulis so I'm more comfortable working in CMYK, especially on people shots.
I'm not concerned that the profiles are not being honored, but that perhaps I could improve results by trying and using other CMYK profiles for the conversion back and forth (as one thing among many), as I have several times noticed, beyond Mike's point on gamut and color vibrancy loss, a shift in color when I do reconvert to RGB for print or web. Were I outputting CMYK to a service provider that would not matter, but for those of us outputting to inkjet printer with RGB input it does.
The commencement of this thread (which I have somewhat rerouted) suggested that this was one possibility to explore for my own closed-loop workflow, provided my input of CMYK space selected would affect the conversion, which thanks to your answer I now know is the case so that I'm not spinning my wheels.
So thanks again for your, and thanks for all the other advice I've received.
Maris
Date: Fri, 22 Nov 2002 23:07:04 -0700
From: Chris Murphy
Subject: Re: please advise on color conversion
Maris V. Lidaka Sr. wrote:> The point of my follow-up question was that PS7 does not use my Epson
> profile nor for that matter CDTobie's profiles when I switch back & forth
> between RGB and CMYK *while working on the image, correcting it*correct
> My question was does PS7 use the CMYK specification that I select on the
> Color Settings panel during the time I am adjusting the image should I elect
> [foolishly ;-)] to convert from RGB to CMYK to color-correct a person's
> face, and back to RGB so I can print the face, or does PS7 use some other
> profile or methodology for that conversion?When you do an RGB to CMYK mode change, the document's assigned profile (which might be the RGB working space, or it might be something else) is used as the source profile. The destination profile will be the CMYK working space. When you do a mode change back to RGB, the source profile is the document's assigned profile (which should be the CMYK working space unless you've changed it since the last time you did a mode change) and the destination is the RGB working space.
Chris Murphy
Color Remedies (tm)
Boulder, CO
www.colorremedies.com
Date: Fri, 22 Nov 2002 23:04:13 -0700
From: Chris Murphy
Subject: Re: please advise on color conversion
Maris V. Lidaka Sr. wrote:> Huh? My inkjet printer (Epson C80) clearly doesn't have a profile usable in
> PS to convert from RGB to CMYK and back to RGB for image color-correction
> purposes (as opposed to its internal RGB to CMYK conversion in the
> printing process).As far as I know, all Epson printers come with canned profiles from Epson for that model of printer, and the Epson brand media they recommend for it. So you should have an Epson profile somewhere on your system so that you can convert RGB and CMYK images to the appropriate Epson RGB space. Just plain RGB isn't good enough (not that there is such a thing...)
> But perhaps I should take a step back - I may be making a wrong assumption.
> Does the CMYK specification in "Working Spaces" on the Color Settings panel
> in PS7 have anything to do with the conversion from RGB to CMYK and back
> while working on the image?Yes, but neither the RGB or CMYK working space will have anything to do with your printer. You still need to tell Photoshop at print time something about the behavior of your inkjet printer by selecting a printer profile. If it's Photoshop 7, you would select this in the Print with Preview window, click on More Options at the bottom of the window, click the pop-up menu and set it to color management, and find the appropriate Epson profile in the Print Space pop-up menu. When you click print and get to the Epson driver itself, select media and resolution settings like normal, select the Custom radio button (instead of Automatic), then click on the Advanced button, and in the Color Management section select the No Color Adjustment radio button. Now print.
Chris Murphy
Color Remedies (tm)
Boulder, CO
www.colorremedies.com
Date: Sat, 23 Nov 2002 07:28:21 -0600
From: "Maris V. Lidaka Sr."
Subject: Re: please advise on color conversion
Thank you as well (though Stephen beat you to the punch). Now we're on the same wavelength and I've got the answer to what I was looking for.Maris
----- Original Message -----
From: "Chris Murphy"When you do an RGB to CMYK mode change, the document's assigned profile (which might be the RGB working space, or it might be something else) is used as the source profile. The destination profile will be the CMYK working space. When you do a mode change back to RGB, the source profile is the document's assigned profile (which should be the CMYK working space unless you've changed it since the last time you did a mode change) and the destination is the RGB working space.
Date: Sat, 23 Nov 2002 09:51:29 -0700
From: Andrew Rodney
Subject: Re: Re: please advise on color conversion
Maris Lidaka wrote:> I learned 'color by the numbers' though from a book by a gentleman
> called Dan Margulis so I'm more comfortable working in CMYK, especially on
> people shots.Wonderful technique IF (big if) you know what the numbers should be. In the case of sending RGB data to an ink jet that will do an internal conversion to some flavor of CMYK (plus possibly a few other colors), the numbers are completely unknown, have no relationship to anything Dan or anyone else has ever printed on a press and therefore useless.
What you really need is to send the correct set or RGB numbers to the Ink Jet. Sorry if you like CMYK numbers but in this case, they are immaterial.
Andrew Rodney
Date: Sat, 23 Nov 2002 18:55:52 -0000
From: "Bob Frost"
Subject: Re: please advise on color conversion
Maris,What is wrong with Adobe98?
Bob Frost.
Date: Sat, 23 Nov 2002 14:11:06 -0600
From: Bob Smith
Subject: Re: Re: please advise on color conversion
Andrew Rodney wrote:> What you really need is to send the correct set or RGB numbers to the Ink
> Jet. Sorry if you like CMYK numbers but in this case, they are immaterial.This thread is going in circles all around what it seems to me that Maris was trying to determine. Editing by the numbers in CMYK is Maris' preferred editing method. The CMYK numbers do mean something predictable as long as the CMYK space that the editing takes place in is known. Maris isn't trying to send those CMYK numbers to the Epson. What's needed is a CMYK space that allows smooth conversions back and forth between RGB and CMYK with as little loss or shifting of colors as possible...maybe this means some sort of custom wider gamut CMYK "working space". This would allow CMYK editing while still making good use of the wider (or just different?) gamut of an Epson printer. I certainly don't have specific recommendations for such a CMYK space but I thought this was something Dan had commented on in the past. Perhaps he'll chime in here... or maybe I'm just taking this thread into still another circle altogether.
Bob Smith
Date: Sat, 23 Nov 2002 15:57:14 -0500
From: Dan Margulis
Subject: Re: please advise on color conversion
Bob writes,>>This thread is going in circles all around what it seems to me that Maris was trying to determine. Editing by the numbers in CMYK is Maris' preferred editing method. The CMYK numbers do mean something predictable as long as the CMYK space that the editing takes place in is known. Maris isn't trying to send those CMYK numbers to the Epson. What's needed is a CMYK space that allows smooth conversions back and forth between RGB and CMYK with as little loss or shifting of colors as possible...maybe this means some sort of custom wider gamut CMYK "working space". This would allow CMYK editing while still making good use of the wider (or just different?) gamut of an Epson printer. I certainly don't have specific recommendations for such a CMYK space but I thought this was something Dan had commented on in the past. Perhaps he'll chime in here...>>
I agree with all of the above. Yes, it's been commented on before; it inevitably degenerates into the colorspace-chauvinist side saying that all conversions are poison and involve "irretrievable data loss"; that unless you know your exact output conditions all corrections are useless; and that you can't tie your shoes unless the shoes have first been characterized and calibrated.
Going from one colorspace to another without pain is trivially easy for non-beginners. If one's output space is Colorspace A there's no reason to avoid doing most of the work in Colorspace B. There *is* a reason to avoid saying that you will never, ever, work in Colorspace A--or Colorspace B, for that matter.
With a few exceptions such as images with critical shadow detail or specific sharpening issues, there's no strong reason to correct in CMYK for RGB output, but there's little reason to avoid it either. If one insists upon doing it, it's marginally more convenient to use one of the "wide gamut" CMYK definitions that have been specially formulated to accommodate changes between CMYK and other spaces with little color variation. A couple of such profiles are included on the CD of the latest edition of Professional Photoshop. But they aren't really necessary.
Dan Margulis
Date: Sat, 23 Nov 2002 16:08:09 -0600
From: "Maris V. Lidaka Sr."
Subject: Re: please advise on color conversion
Nothing - but it's an RGB space and has nothing to do with the degree of accuracy of the back and forth conversion process, which is what I was asking about. Whatever RGB space I start with I will return to.Maris
----- Original Message -----
From: "Bob Frost"What is wrong with Adobe98?
Date: Sat, 23 Nov 2002 16:06:50 -0600
From: Maris V. Lidaka Sr.
Subject: Re: Re: please advise on color conversion
Thank you for the heads up re the profiles on the CD - the several images I noticed problems with may be among the exceptions, so I'll try them. I had read a previous version of the book and have bought Professional Photoshop [7] but haven't had time to read it yet.Maris
Date: Sun, 24 Nov 2002 11:19:41 -0500
From: John Castronovo
Subject: Re: Re: Proof color in Photoshop Info palette
> If all you want is a nice print from your ink jet, there is no reason to
> convert to CMYK (and plenty of reasons not to).
>
> Andrew RodneyYes indeed, unless you like larger files that are harder and slower to edit with reduced color gamut and arcane CMYK rules that make little to no sense to what was RGB image in the first place. Oh, and I left out the ability to better re-purpose the file for other output in the future.
john castronovo
Date: Sun, 24 Nov 2002 12:23:50 -0000
From: "Bob Frost"
Subject: Re: please advise on color conversion
Maris,I couldn't understand why you would want to use a CMYK space. From everything I have read, there is no advantage in going from RGB to CMYK to RGB in PS and then back to CMYK again in the printer, and lots of scope for losing color accuracy. Having now read your later postings, I understand why you wanted to do it, but still think you are misguided.
Bob Frost.
Date: Sun, 24 Nov 2002 01:42:29 -0800
From: Raymond St. Arnaud
Subject: Re: please advise on color conversion - RGB
Would this be an apprpriate moment to discuss the RGBX color space. I know little of it as Dan's latest book just arrived from amazon.ca after a very lengthly wait.Regards
RayRaymond St. Arnaud, Victoria, B.C., Canada
Photography and Digital Illustration
http://www.worldprintmakers.com/shows/arnaud/starnaud.htm
http://www.ylem.org/artists/RSArnaud/ray-a.htm
http://www.islandillustrators.org/membpage/s-arnaud/ray-a.htm
----------------------------------------------------------------
Date: Sat, 23 Nov 2002 18:59:24 -0700
From: Andrew Rodney
Subject: Re: Re: please advise on color conversion
Bob Smith wrote:> Editing by the numbers in CMYK is
> Maris' preferred editing method.And a good one when the numbers you end end up going to an output device. If not, what1s the point?
> The CMYK numbers do mean something
> predictable as long as the CMYK space that the editing takes place in
> is known.But it's not as the black box in the printer is doing this. The RGB to CMYK (plus whatever colors) conversion isn't anything we have a profile for that
Photoshop could use to set the info palette. Photoshop has no idea what recipe of CMYK will be created inside the driver.Andrew Rodney
Date: Mon, 25 Nov 2002 01:38:54 -0000
From: Stephen Marsh
Subject: Re: please advise on color conversion
I agree with the other posts that we are chasing our tail on this thread. Now that we are past the inkjet colour space input issues -we are back to one of the mainstays of this list... Milking the most out of each colour mode, and those that see no benefit from using anything which is not RGB (or CMYK for that matter) - and those of us who know better (those who are on this list becuase of Dan's ideas and methods).Yes, it is agreed that there are many reasons not to go to CMYK when the original is RGB and the output is fed RGB.
But we would be missing out on SO MUCH if we ignored LAB and CMYK as possible helpers in our quest for the 'perfect' image - just because they were not RGB.
This is what Dan's books are all about, you can choose to shackle yourself with only one mode as some suggest - or as Dan has shown us we can often do much better by being open to other possibilities. At the same time, as with all edits - we have to ask ourself is the result worth the effort and are things 'better' than before the edit?
Imagine a commercial setting where RGB input for output was the standard practice. One shop only uses RGB, the other does not have a bias and uses CMYK, LAB or whatever it can to get the job done better than the next guy. Sure, there are limits to what CMYK can do before it impacts on the wider gamut of a common RGB original - but as long as you stay within those limits you have a powerful edge on your competition. Even if you are 'just' a hobbiest and you want to get
the 'best' print possible, there is perhaps something to be gained by exploring other spaces and what they can offer.Back to the case at hand. Portrait work was mentioned by Maris as one thing that CMYK is good for. I agree. LAB is great too, often for opposite reasons that CMYK is good for faces. So with a RGB original and a RGB input for output, and a 'face' as the primary area of concern...I am very confident that a user who only used RGB would not be getting as good results as someone who blended CMYK and LAB edits into their RGB origianl.
The key is not loosing richer colours in the RGB, while still getting a benefit from the lower gamut CMYK editing space. As this mail is getting long - I will have to cut things a bit short...
Three brief points to consider:
* Some images colours or tones do not visually suffer from a RGB to CMYK move, others do. Play things smart where you can and blend or mask things back into the original RGB. In many cases the CMYK edits may not be needed on the whole image but only on selective areas or perhaps on the luminosity and not the colour component of the image.
* Many CMYK edits for RGB output are for the shadow detail or for
fine tuning luminosity or sharpening. Many of these edits can be selectively blended or masked into the shadow areas of a RGB original without affecting colour areas - or luminosity tweaks in CMYK can be luminosity blended into the RGB so that the hue/saturation component is not affected (when globally applying the CMYK edits to the RGB without masks).CMYK does not have to hurt your original RGB, it can actually help (when done right or with the right type of image).
* R=C G=M B=Y and C=R M=G Y=B (in theory at least). Using a good CMYK as reference to RGB edits in info palette - you can have an understanding of what your RGB edits are doing (just as LAB or HSB or greyscale number previews can be a huge aid in understanding your edits...by the numbers works in all modes!!!).
The problem often is that an edit in the R channel will often affect more than just the C channel of CMYK...but with CMYK number previews, CMYK softproofs then it is fairly easy to work in RGB with a CMYK mindset (but you do miss the K channel and many other things).
Regards,
Stephen Marsh.
Date: Sun, 24 Nov 2002 20:04:38 -0600
From:Maris V. Lidaka Sr.
Subject: Re: Re: please advise on color conversion
A fine close to this thread. Thank you, Stephen.Maris
Stephen Marsh.au wrote:> But we would be missing out on SO MUCH if we ignored LAB and CMYK as
> possible helpers in our quest for the 'perfect' image - just because
> they were not RGB.I don1t disagree with this a lick. What I think is amusing is attempting to come up with some magic numbers in CMYK when the device we are sending a file to doesn1t understand that recipe one bit. The device is expecting RGB data. The CMYK numbers are complete science fiction because we don1t have a clue what are the CORRECT numbers in CMYK to be shooting for. Does anyone really believe we should be editing RGB data while looking at CMYK numbers that are provided by a profile that is for SWOP V2 and think those values in any way are correct for an ink jet printer using 7 inks? If so, I1d like to see some empirical data to back this up.
If you want to load some arbitrary profile (and you have to load a profile to get numeric values for CMYK from an RGB file), and edit a file based on those CMYK numbers, far from me to complain. As long as the user understand the CMYK numbers in no way correlate to the device the RGB file will be sent.
Digital images in ANY colorspace are just numbers (one1s and zero1s) and unless you know what these numbers will produce on the output device, the numbers are pretty useless. It1s like loading a SWOP coated V2 profile, looking at the values, editing the file and then sending those numbers to a color laser printer. Ain1t going to fly kids.
> Using a good CMYK
> as reference to RGB edits in info palette - you can have an
> understanding of what your RGB edits are doingOK so what CMYK reference (profile, admit it) should I load to get values from an RGB file that will be sent to an Epson 2200 running Matt black ink to archival matt paper? What reference do I use when the output is an Iris printing on the same paper?
Andrew Rodney
Date: Mon, 25 Nov 2002 09:35:17 -0600
From: "Maris V. Lidaka Sr."
Subject: Re: Re: please advise on color conversion
Hyperbole. The CMYK numbers we are shooting at are close to, though no doubt not identical to, the CMYK numbers the inkjet converts the file to. Else what appears on the monitor would not be close to what appears on the print.Maris
----- Original Message -----
From: Andrew RodneyIf you want to load some arbitrary profile (and you have to load a profile to get numeric values for CMYK from an RGB file), and edit a file based on those CMYK numbers, far from me to complain. As long as the user understand the CMYK numbers in no way correlate to the device the RGB file will be sent.
Date: Mon, 25 Nov 2002 10:05:06 -0600
From: Bob Smith
Subject: Re: Re: please advise on color conversion
The numbers don't have to mean anything with regard to a specific output device in order to edit in that space. There's no device on the planet that I'm aware of that outputs anything close to what Adobe RGB describes yet we routinely advocate that color space for editing. The same can be true for CMYK as well. What's important is understanding the relationship between the numbers and how moves on those ratios affect the image. For someone that doesn't routinely edit in CMYK, the relationship of the numbers can appear baffling compared to RGB working spaces. For someone well versed in CMYK editing the reverse may be true. And there are of course specific moves that are better done in one space or another. So while editing in CMYK when ultimate output is in RGB may be rare, it is every bit as valid and useful as editing in RGB when the ultimate output is CMYK; or even editing in RGB working spaces when ultimate output is an entirely different flavor of RGB.Bob Smith
On Monday, November 25, 2002, at 08:09 AM, Andrew Rodney wrote:
> I donÕt disagree with this a lick. What I think is amusing is
> attempting to
> come up with some magic numbers in CMYK when the device we are sending
> a file to doesnÕt understand that recipe one bit.
Date: Mon, 25 Nov 2002 09:47:52 -0700
From: Andrew Rodney
Subject: Re: Re: please advise on color conversion
Maris Lidaka wrote:> Hyperbole. The CMYK numbers we are shooting at are close to, though no
> doubt not identical to, the CMYK numbers the inkjet converts the file to.
> Else what appears on the monitor would not be close to what appears on the
> print.You really think an Epson 2200 running UltraChrome 7 color inks behaves like
a 4 color press using process inks????Why don1t you convert the file to CMYK using any CMYK profile you like and send those numbers directly to the ink jet and tell us how the output is.
Andrew Rodney
Date: Mon, 25 Nov 2002 10:26:07 -0700
From: Andrew Rodney
Subject: Re: Re: please advise on color conversion
Bob Smith wrote:> There's no device on the
> planet that I'm aware of that outputs anything close to what Adobe RGB
> describes yet we routinely advocate that color space for editing.That's correct. That's why you have an output profile that produces known values to a known device. You would never send Adobe RGB to a printer. You would however be able to edit IN Adobe RGB and see the output numbers (in RGB or CMYK) for any output device you intend to send the numbers to. With Photoshop 7's Proof Colors in the info palette, you can see any set of numbers for an output device of which you have a profile. But the numbers don't work at all if the profile producing the numbers isn't anything like the device you are going to actually send the numbers to.
Adobe RGB is an editing space so it can become ANY output space you want.
ANY CMYK space is by nature an output space. Tell me what CMYK values will always produce a neutral? In a Working Space I can do this.
> So while editing in CMYK when ultimate output is
> in RGB may be rare, it is every bit as valid and useful as editing in
> RGB when the ultimate output is CMYKRGB Working Spaces are never device output specific, they are always gray balanced and many have gamma's that insure even editing over the tonal scale. These spaces truly are quisi-device independent spaces.
CMYK is always an output space. That's the main difference. The two are not the opposite of the same coin. It's much like editing RGB in an input space (scanner or camera). It can be done but it's real dicy, especially if you're dealing with linear input. The numbers are really wacko but the data is pristine and easily brought into an RGB Working Space where the numbers are truly something you can bank on (R=G=B is neutral).
Andrew Rodney
Date: Mon, 25 Nov 2002 11:45:59 -0600
From: Maris V. Lidaka Sr.
Subject: Re: Re: please advise on color conversion
It depends on what you mean by "behaves like" - it does in that the same CMYK numbers will result in images appearing almost identical, the Epson internally converting to use of its multiple inks. Only the methodology is different.If I were using a RIP I would send the CMYK file to the printer. Since I am not I send RGB. My use of CMYK is solely for adjustment of the image, but I want as little change as possible in re-converting to RGB.
Are you really suggesting that no conversion other than between CMYK and LAB, or between RGB and LAB, ever be made?
Maris
----- Original Message -----
From: Andrew Rodney
You really think an Epson 2200 running UltraChrome 7 color inks behaves like a 4 color press using process inks????Why don1t you convert the file to CMYK using any CMYK profile you like and send those numbers directly to the ink jet and tell us how the output is.
Andrew Rodney
Date: Mon, 25 Nov 2002 09:59:57 -0700
From: Chris Murphy
Subject: Re: Re: please advise on color conversion
Maris V. Lidaka Sr. wrote:> Hyperbole. The CMYK numbers we are shooting at are close to, though no
> doubt not identical to, the CMYK numbers the inkjet converts the file
> to.I seriously doubt they are anywhere near close. In nearly all cases where I've worked with inkjet printers attached to a PostScript RIP, the raw CMYK behavior of an inkjet printer is completely unlike a printing press. The few where that wasn't the case, they were printers specifically geared toward the simulation of offset presses by using appropriate media and inksets. In all consumer inkjets, there is no cyan in the printer at all, and no magenta either. It's closer to blue and red respectively. The yellow varies wildly from a nearly fluorescent yellow to basically yellow-orange. The tone reproduction curve is also quite unlike that of a printing press.
> Else what appears on the monitor would not be close to what appears on > the print.
This is not a logical conclusion supported by fact. That you get something reasonable is only because the Epson printer driver is doing the work of hiding the rather bizarre, if not hideous, raw CMYK behavior of the inkjet printer. The is an internal separation occurring in the printer driver that is closed and proprietary. There is no way you can control individual CMYK channels with a non-PostScript printer. Period.
What this amounts to is if you have the ability to do a certain thing in CMYK but you can't do it in RGB (primarily through lack of knowledge or experience at doing that something in RGB), then it makes sense to use a CMYK technique because that's all you've got to work with. But from a technical aspect, corrections in CMYK absolutely have no inherent advantage or control on an RGB image that is going to be separated with parameters beyond your control, as is the case with a non-PostScript inkjet printer.
If you need this level of control, get a RIP that will give you direct control over the CMYK values of the printer - and hopefully will tame the CMYK behavior as well so that you don't have to wrestle with it.
Chris Murphy
Color Remedies (tm)
Boulder, CO
www.colorremedies.com
Date: Mon, 25 Nov 2002 11:07:09 -0700
From: Andrew Rodney
Subject: Re: Re: please advise on color conversion
Maris Lidaka wrote:> Are you really suggesting that no conversion other than between CMYK and
> LAB, or between RGB and LAB, ever be made?Sure but not if the conversion gains nothing...
Date: Mon, 25 Nov 2002 11:17:51 -0700
From: Chris Murphy
Subject: Re: Re: please advise on color conversion
Andrew Rodney wrote:> Why donÕt you convert the file to CMYK using any CMYK profile you like and
> send those numbers directly to the ink jet and tell us how the output is.Actually, it needs to be placed in QuarkXPress and then printed from QuarkXPress to take advantage of it's fantastic CMYK to RGB conversion. If it's printed from Photoshop, it will probably convert it to a reasonable RGB space and something reasonable will get printed.
Chris Murphy
Color Remedies (tm)
Boulder, CO
www.colorremedies.com
Date: Mon, 25 Nov 2002 15:42:48 -0500
From: Derek Cooper
Subject: RE: Printing to inkjet--from a lurker
>>Anyway, my questions are, would I be well-served by Dan's books, and if so, which? Or, would they be overkill for my needs? If this question, or the information I provided is too vague, please let me know and I'll expand on my current colour-management methods and tell you precisely what my set-up is. I didn't want to go into more detail here until I got the go-ahead.>>If you could share your current setup, that would be terrific. For example, do you profile your monitor? Have you considered buying / having custom print profiles made? What ink you are using in the printer if different than the standard Epson cartridges?
Cheers,
Derek Cooper
www.derekcooper.com
Date: Mon, 25 Nov 2002 12:59:42 -0700
From: Chris Murphy
Subject: Re: Re: please advise on color conversion
Maris V. Lidaka Sr. wrote:> Are you really suggesting that no conversion other than between CMYK
> and LAB, or between RGB and LAB, ever be made?I am suggesting if the original is RGB and the output device is RGB, you should be editing primarily in RGB and in some unique cases perhaps LAB. I fail to see the benefit of using CMYK correction techniques on an RGB image destined for RGB output unless you simply aren't familiar with the equivalent RGB correction technique.
Chris Murphy
Color Remedies (tm)
Boulder, CO
www.colorremedies.com
Date: Mon, 25 Nov 2002 14:50:39 -0700
From: Ron Kelly
Subject: Re: Re: please advise on color conversion
Chris Murphy wrote:> I fail to see the benefit of using CMYK correction techniques on
> an RGB image destined for RGB output unless you simply aren't familiar
> with the equivalent RGB correction technique.Chris:
I use my inkjet for desktop proofs (via cmyk RIP) of offset press, but I also print directly to it for an end result (rgb only data from scanner to printer).I'm not familiar, for example, on how to make good skin tones in rgb, yet I feel that I can do so in CMYK. What do you suggest for me?
Ron Kell
yDate: Mon, 25 Nov 2002 22:08:56 -0000
From: Stephen Marsh
Subject: Re: please advise on color conversion
> I don1t disagree with this a lick. What I think is amusing is attempting to
> come up with some magic numbers in CMYK when the device we are sending a
> file to doesn1t understand that recipe one bit.Throughout this entire thread, this has never been the situation. I think you are under a false impression of the original series of points stated by Maris if this is so.
As suggested by Bob Smith - the CMYK in use by Maris was used as a 'work space' to get whatever edit done. As with a RGB work space - the final data is still converted to the OUTPUT space.
A CMYK edit converted to RGB still keeps its visual appearance. If I am tweaking shadow detail in the K channel those moves will translate into the RGB file after I leave CMYK.
> OK so what CMYK reference (profile, admit it) should I load to get values
> from an RGB file that will be sent to an Epson 2200 running Matt black ink
> to archival matt paper? What reference do I use when the output is an Iris
> printing on the same paper?That would be the "Epson 2200 running Matt black ink to archival matt paper.icc".<g> What else would you expect the correct values to be gained from?
If you mean what I think you really mean - whatever works for the edit you are doing.
In most cases this would be the Custom CMYK, as the most probable reason for taking a dupe into CMYK would be for the K channel...and unless you feel like generating a new profile whenever you want to tweak K generation the less than ideal custom CMYK would be it.
Stephen Marsh.
Date: Mon, 25 Nov 2002 18:07:47 -0600
From: "Maris V. Lidaka Sr."
Subject: Re: Re: please advise on color conversion
Your point is well taken, as is Chris's that RGB input should primarily remain in RGB throughout editing if output is RGB. Unfortunately, I am one of those who, as Chris put it, isn't yet sufficiently "familiar with the equivalent RGB correction technique", especially for facial tones - hence my concern that the RGB-CMYK conversion within Photoshop be as accurate as possible, as my use of CMYK is as a work space as Stephen and Bob suggest.At any rate, at this point I will bow out as I am not advocating that RGB should be converted to CMYK if output is in RGB but was concerned only with the most accurate conversion when it is made. I thank you, Stephen, and all the others, as I have learned a great deal more from this discussion than merely the answer to my question.
Maris
Date: Mon, 25 Nov 2002 16:23:58 -0700
From: Andrew Rodney
Subject: Re: Re: please advise on color conversion
Stephen Marsh wrote:> As suggested by Bob Smith - the CMYK in use by Maris was used as
> a 'work space' to get whatever edit done.The very process of converting an RGB file (from a true working space) to a CMYK (a true output space) alters the data and there is no going back. What CMYK space is the conversion going to FROM RGB? Even if this new space has no bearing on an output space, I don1t buy for a second that the conversion from RGB to CMYK (for the only purpose of editing) back to RGB will not alter the resulting RGB a lot (even if we discount the edits). Taking a file from Adobe RGB to SWOP V2 back to Adobe RGB produces a vastly different Adobe RGB file in the end.
Does someone really have a wide gamut CMYK space that fully contains all gamut of the original Adobe RGB working space?
> A CMYK edit converted to RGB still keeps it's visual appearance.
It's the original conversion from RGB to "CMYK Work Space" that really alters the appearance. That's the big problem here.
Andrew Rodney
Date: Tue, 26 Nov 2002 00:49:57 -0000
From: Stephen Marsh
Subject: Re: please advise on color conversion
> The very process of converting an RGB file (from a true working space) to a
> CMYK (a true output space) alters the data and there is no going back.Agreed, data is changed.
> What CMYK space is the conversion going to FROM RGB? Even if this new space has
> no bearing on an output space, I don1t buy for a second that the conversion
> from RGB to CMYK (for the only purpose of editing) back to RGB will not
> alter the resulting RGB a lot (even if we discount the edits).Agreed.
This is why things are done in a dupe a selectively blended back into the original RGB.
I have never suggested simply converting the original master archive from RGB to CMYK blindly and then back again. Nor have I recommended globally replacing the RGB data with converted/edited data - just selected parts. And when a more global approach is required, the blend is often only affecting the luminosity component of the RGB original and not the hue/chroma (again masks and other blending tricks can come into play to produce more selective results).
> Taking a file
> from Adobe RGB to SWOP V2 back to Adobe RGB produces a vastly different
> Adobe RGB file in the end.Yes. It also depends on the 'image' and the colours it contains. It is possible to create a A98 file which shows no visible loss when converting, just as it is possible to make one which does suffer.
When it comes to natural images, then things are not so clear cut. Some areas may visually suffer more so than others.
As I have mentioned previously, apart from the situation that Maris is in - most benefits of CMYK edits are shadow detail hacks to the K channel or reducing total ink to create the required result in RGB when blended back to the original file.
As well as targeted shadow detail and other content which may be exposed in a K channel - CMYK can also be helpful when luminosity tweaks are needed. Having four sets of luminosity curves can give more control in some cases, as are the minor/major differences between how colours map to RGB/CMY(K) colour modes.
Again, this can be blended into key areas via a luminosity blend (or globally via a luminosity blend).
As an example - for a long time I have converted to custom greyscale using various methods which are all based off various weights/combinations of the RGB channels. After some exploration of using CMYK as the channel mixing/blending mode I am finding the options available in CMYK to be more flexible than RGB.
When it comes to objects that have a high amount of black detail - there is nothing better than CMYK to edit in. RGB/LAB/HSB etc all lack the K channel, which is great for this work as Dan has shown in MakeReady articles and in his books. I have also proven this for myself in my own edits and results so I am not just blindly following Dans words.
In addition to the K channel - some ICC profiles have a severe luminosity shift (more so than gamut mapping/compression accounts for) in the Perceptual render intent, which is not there in the RelCol render. Although I usually avoid the Perceptual render if this is the case with the profile - this extra 'benefit' can also be used to quickly 'correct' a file with critical shadow detail (in addition to targeted K channel edits). So shadow detail building can be performed in a dupe and then blended back into the original RGB/CMYK file in numerous ways in an attempt to gain from the K channel or other targeted CMYK edits without overly impacting on the gamut of the majority of the origianl RGB file.
Stephen Marsh.
Date: Mon, 25 Nov 2002 20:11:29 EST
From: Dan Margulis
Subject: Re: Re: please advise on color conversion
Chris Murphy writes,>I fail to see the benefit of using CMYK correction techniques on
>an RGB image destined for RGB output unless you simply aren't familiar
>with the equivalent RGB correction technique.It's hard to see the benefit of using an airplane unless you simply aren't familiar with how to make a car fly.
Nobody wants to shift colorspaces just for the sport of it. One only does so when one isn't familiar with the equivalent technique in the current space, or believes that it's much more time-consuming than just dropping into another space and then coming back.
Stephen's two posts contain many examples of areas, such as CMYK shadow augmentation, where he is not familiar with the equivalent technique in RGB, and Stephen is clearly an expert by anybody's measure. There are many blending combinations in RGB where I'm not familiar with the CMYK equivalent technique; not quite so many vice versa, but they exist. And there is a large array of LAB maneuvers for which I am not familiar with the equivalent technique in either RGB or CMYK.
Dan Margulis
Date: Mon, 25 Nov 2002 18:05:30 -0800 (PST)
From: Mike Bevans
Subject: Re: Re: please advise on color conversion
I may be getting my threads mixed up, but here goes anyway.The discussion, as always seems to be centered on RGB v. CMYK as far as editing and output. I will try not to repeat what others have said, but when we discuss profiles, it seems we can go around in these circles for a long time.
First, as may have been mentioned, RGB spaces, such as AdobeRGB1998, AppleRGB, sRGB stc. are working spaces. This could imply that these are the spaces you work in.
I have found it helpful to consider "monitor" as a verb, rather than as a noun. When I am in my working space, I am monitoring my recording. The settings I choose to have my montior tuned to does not effect the data of the file. I can flip working spaces til the end of time, and the data of my file remains the same.
If I want to maintain the look of AdobeRGB1998, but work in sRGB because that is how my desktop printer works, then I can convert from AdobeRGB1998 to sRGB. Visually they look the same.
By converting to, or embedding an RGB profile, I can inform the next person who views my shot the conditions I looked at my image under. Of course, to accurately view this data, I should normalize my instruments to known standards. This is what Adobe gamma and a whole host of calibrators do.
Now, editing to a color space means you hope that the machine that outputs your files can match the performance dictated by that space. If you are making a print to a specific printer, with a specific paper, you can "monitor" the appearance of your output by using a profile... if only as a print preview. This will allow your monitor, which by most accounts has a broader gamma than your output, to show you the way your printer will represent the data you are viewing.
I may not be as savvy as most when it comes to the use of output profiles, but I have spent my share of time working with photographers, prepress, retouchers, press, etc. and have made my share of match prints. It may well be that the very tools that everyone uses for color correction may not be performing the functions they expect.
Working as a consultant, I have seen how many photographers, prepress, and retouchers work. I have noticed that a good deal of the "color correction" is done using curves.
What I hope to add to this discussion, is that curves are not a color correction. At least not the curves in Photoshop. Curves define the sensativity of your recording to light, just like the curves of film. Any time you change curves, you are altering the exposure. This is why people will talk about clipping information. When you alter the exposure of your recording, you can only remove, you can't add.
Happy editing.
Michael Bevans
Date: Thu, 21 Nov 2002 12:33:17 -0600
From: Al MacDonald
Subject: JPEG's
Do any of you pre press folks have any insight on reproduction qualities of JPEG files? To be more succinct; would I encounter any problems with color fidelity and detail on files saved as high res setting JPEG vs. my usual workflow of saving TIFF's or EPS?We are photographing a project with several hundred images. Our client wants CD's of all files and our camera produces 49 meg TIFF's. Needless to say, we end up burning dozens of CD's for the job. Client wants to know if we can give him JPEG's instead and not loose too much quality when image goes to press.
Any thoughts appreciated.
Thanks.
--
Al MacDonald
Shaughnessy MacDonald, Inc.
Elk Grove Village, IL 60007
http//www.shaumac.com
Date: Thu, 21 Nov 2002 16:48:26 EST
From: Jeff Tytel
Subject: Re: JPEG's
Al,
Have you considered saving as an EPS with JPEG compression (MAXIMUM). I provide a lot of the images I produce over e-mail in this format and it really works the best for compressing images with very little loss of detail. Also, a 10 MB file ends up at around 2.5 or 3 MB when saved.Jeff Tytel
Date: Thu, 21 Nov 2002 17:33:33 -0500
From: Tom Judd
Subject: Re: JPEG's
Al MacDonald wrote:
> Do any of you pre press folks have any insight on reproduction qualities of
> JPEG files? To be more succinct; would I encounter any problems with color
> fidelity and detail on files saved as high res setting JPEG vs. my usual
> workflow of saving TIFF's or EPS?I think people are way too afraid of JPEGs. Don't use them as your working file format during the time they will be opened and resaved several times. But as a final output format, a max quality JPEG will work just fine for most uses.
You can get a 5x to 10x reduction in size with artifacts so minimal that even expert observers have trouble seeing them (I once did a subjective experiment to verify this).
Date: Thu, 21 Nov 2002 16:47:32 -0700
From: Andrew Rodney
Subject: Re: JPEG's
on 11/21/02 11:33 AM, Al MacDonald wrote:> Do any of you pre press folks have any insight on reproduction qualities of
> JPEG files? To be more succinct; would I encounter any problems with color
> fidelity and detail on files saved as high res setting JPEG vs. my usual
> workflow of saving TIFF's or EPS?If you keep the compression roughly 10:1 or less, you1ll get visually lossless compression. You can1t see it but it happened. So unless you are doing a lot of editing on the file (and thus doing a new compression at each save), you should be fine with JPEG.
Andrew Rodney
Date: Fri, 22 Nov 2002 07:59:59 -0500
From: "Owen Colborne"
Subject: jpeg's
We have had success providing EPS with jpeg maximum quality. Much smaller files that print faster.
Cheers,
Owen Colborne
Digital Photography Specialist
Que-NET Mediaª
a Member of the Quebecor World Group
2250 Islington Ave
Toronto, Ontario, Canada M9W 3W4
416-745-5588 x351
Date: Fri, 22 Nov 2002 09:10:30 -0700
From: Ron Kelly
Subject: Re: jpeg's and image compression
Owen Colborne wrote:> We have had success providing EPS with jpeg maximum quality. Much smaller
> files that print faster.Hi Group:
Has anyone tried the new format: SkinnyEPS 2.0? You can download a demo at http://www.ultimate-tech.com. I've read about it but I've not had a chance to try it. They claim that it reduces file size by 15 times with no loss of quality.Ron Kelly
Date: Fri, 22 Nov 2002 08:46:11 -0800
From: Mac Townsend Mac Townsend
Subject: Re: JPEG's
this prescription provides eps files that some applications cannot separate.> Have you considered saving as an EPS with JPEG compression (MAXIMUM). I
> provide alot of the images I produce over e-mail in this format and it really
> works the best for compressing images with very little loss of detail. Also,
> a 10 MB file ends up at around 2.5 or 3 MB when saved.
>
> Jeff TytelMac Townsend
Adcom Graphics, Digital Imaging
Fairfield, California
www.adcomgraphics.com
Date: Sun, 24 Nov 2002 19:50:36 -0800
From: "Darren Bernaerdt"
Subject: RE: JPEG's
Check with whomever is ripping the files - printer, service bureau, etc. - before using this combo (EPS with JPEG compression) just to ensure their RIP supports it. We have been successfully using this format for about four years on large run jobs (web press) on newsprint and No. 5 sheet. If your press conditions are really good, you may want to assemble a test first to make sure your pleased with the quality.One tip, though - I would suggest not embedded an ICC profile if you're trying to save space and are using Photoshop 6 or 7. We use the "built in" or custom CMYK settings to define our CMYK conversions. Embedding that in the file balloons the file size and probably isn't being used by anyone later on in the process.
Darren Bernaerdt
Senior Photographer, London Drugs Ltd.
Date: Mon, 25 Nov 2002 22:51:20 -0500
From: John Castronovo
Subject: Re: JPEG's
> One tip, though - I would suggest not embedded an ICC profile if you're
> trying to save space and are using Photoshop 6 or 7. We use the "built in"
> or custom CMYK settings to define our CMYK conversions. Embedding that in
> the file balloons the file size and probably isn't being used by anyone
> later on in the process.A better way to save file space is to keep it RGB and leave the profile. Having a profile is never a bad thing. Even if it doesn't get used, it tells the recipient more about what it's supposed to look like than having nothing at all. No profile and no proof means that the color is whatever comes out. It's your nickel.
John Castronovo
Date: Mon, 25 Nov 2002 23:11:29 -0500
From: John Castronovo
Subject: Re: Re: please advise on color conversion
My GOD! Quark has never even been a contender where color management is concerned. The only way to make it work is to turn off color management in Quark and use Praxisoft's Compass Pro plug-in to do the color management on output. Photoshop will convert quite well - if you set it up correctly. One can also use Adobe In-Design which handles color management as well as Compass Pro with Quark, but it comes that way so there's nothing extra to buy.john castronovo
>Actually, it needs to be placed in QuarkXPress and then printed from
>QuarkXPress to take advantage of it's fantastic CMYK to RGB conversion.
>If it's printed from Photoshop, it will probably convert it to a
>reasonable RGB space and something reasonable will get printed.>Chris Murphy
Date: Tue, 26 Nov 2002 05:15:55 -0000
From: Stephen Marsh
Subject: Re: please advise on color conversion (Ron)
Chris Murphy wrote:> > I fail to see the benefit of using CMYK correction techniques on
> > an RGB image destined for RGB output unless you simply aren't familiar
> > with the equivalent RGB correction technique.Ron Kelly replies:
> I use my inkjet for desktop proofs (via cmyk RIP) of offset press,
> but I also print directly to it for an end result (rgb only data from
> scanner to printer).
> I'm not familiar, for example, on how to make good skin tones in
> rgb, yet I feel that I can do so in CMYK. What do you suggest for me?Ron, things are often similar.
If you wish to ignore CMYK totally, then rely on your trusted calibrated/profiled monitor. Move the R curve to do similar things as the C in CMYK, G for M and B for Y. When you are happy with the inkjet softproof then you are done.
As for the RGB info palette - I do not find it easy to think in RGB ratios and values when evaluating or editing skin tone...but it can be done. Not sure how different RGB work spaces affect the balance of the ratios between R-G-B but that's not my problem, as I do not base skin tone evaluations off RGB number ratios.
But you can also use a CMYK space info preview that you feel comfortable with, if you feel lost trying to work out what colour those RGB values mean.
If working in RGB I use RGB info values for endpoints and neutrals - but when it comes to memory colours, I use a SWOP type profile to evaluate my RGB edits off - as well as visual monitor results.
I find it a very simple and quick thing to look at the ratio and balance of CMY+K values in the info palette and to then understand what is taking place when evaluating a sky, grass or skin colour for example.
It is then a simple matter to move the RGB curves but to evaluate these by both visual and the CMYK work space values.
To my mind evaluating and mixing colour in the CMY model is far more 'intuitive' than in trying to think in RGB values...but that is just me. Perhaps if I grew up painting on a computer with RGB values instead of with traditional media I would feel different about the subject.
Stephen Marsh.
Date: Mon, 25 Nov 2002 23:53:47 -0800
From: Darren Bernaerdt
Subject: RE: JPEG's
I believe the original thread was assuming CMYK output, though I may be incorrect.I would be very uncomfortable sending a client a RGB file if the final output is CMYK. That invites a simple RGB>CMYK conversion with no regard for the final product. Some communication about the project would allow for a thoughtful, measured conversion to CMYK, thus protecting the intent of the original image. Generally, I believe as the creator of the image I have one the greatest stakes in the quality of the image when the ink hits the paper.
Do you honor every embedded profile in files you receive from other people?
Darren
> A better way to save file space is to keep it RGB and leave the profile.
> Having a profile is never a bad thing. Even if it doesn't get
> used, it tells
> the recipient more about what it's supposed to look like than
> having nothing at all.
Date: Tue, 26 Nov 2002 04:17:47 -0500
From: John Castronovo
Subject: Re: Re: please advise on color conversion (Ron)
>To my mind evaluating and mixing colour in the CMY model is far
>more 'intuitive' than in trying to think in RGB values...but that is
>just me. Perhaps if I grew up painting on a computer with RGB values
>instead of with traditional media I would feel different about the
>subject.That's amusing to me, Stephen, because I grew up as a photographer and to my way of thinking in terms of color, nothing could be stranger and more awkward than CMYK. It's perfectly natural that red and green light make yellow and that all colors together make white and nothing makes black. CMY can be as easy as RGB, but throwing in a black channel confuses everything. Once you get the hang of it, I suppose anything can make sense, but isn't juggling three balls easier than three balls and a brick?
john castronovo
Date: Tue, 26 Nov 2002 13:17:36 -0000
From: Stephen Marsh
Subject: Re: please advise on color conversion (Ron)
> That's amusing to me, Stephen, because I grew up as a photographer and to my
> way of thinking in terms of color, nothing could be stranger and more
> awkward than CMYK.LOL, my prepress background predisposes me to look at colours and think 'what build of SWOP type CMY(K) makes up that colour'...Hours of fun and entertainment for your friends and family!<g>
> It's perfectly natural that red and green light make yellow
I think it is perfectly natural for red to be made from M+Y and green from C+Y and Y for Y is great (it's just a shame that I deal with more reds and greens than yellows in my CMYK work).
Yes, pure primaries/secondary hues are easy - but what about when you start mixing finer increments of those three primaries together?
> and that all colors together make white and nothing makes black.
I agree that those are easy to grasp.
> CMY can be as easy as RGB, but throwing in a black channel confuses everything.
K can replace some CMY to achieve the same result (in theory). For many edits - the K does not even affect the colour in question due to lighter GCR often being used over heavier K generation.
> Once you get the hang of it, I suppose anything can make sense, but isn't
> juggling three balls easier than three balls and a brick?The major problem I have found is when I drop the brick on my foot.
Stephen Marsh.
Date: Tue, 26 Nov 2002 08:27:49 EST
From: Dan Margulis
Subject: Re: Re: please advise on color conversion
Mike Bevans writes,>First, as may have been mentioned, RGB spaces, such as AdobeRGB1998, AppleRGB,
>sRGB stc. are working spaces. This could imply that these are the spaces
>you work in.It could imply almost any number of things, granted that the people who coined the term "working space" almost uniformly have no real-world color experience, and start from the assumption that any colorspace other than RGB is poison. There's no reason to avoid an LAB working space, or a CMYK working space, or an HSB working space, or an xyY working space.
>I have found it helpful to consider "monitor" as a verb, rather than as
>a noun. When I am in my working space, I am monitoring my recording.
>The settings I choose to have my monitor tuned to does not effect the data
>of the file. I can flip working spaces til the end of time, and the data
>of my file remains the same.Not so, see below.
>If I want to maintain the look of AdobeRGB1998, but work in sRGB because
>that is how my desktop printer works, then I can convert from AdobeRGB1998
>to sRGB. Visually they look the same.Yeah, provided you don't have anything resembling a bright color in the image. If you convert 25r250g25b, a reasonably bright green, from Adobe RGB to sRGB and back again, you get 141r250g59b. Having some experience with color-blind people, I can attest that most color-blind people could tell the difference between these two colors. Even a relatively subdued cyan, like 50r200g200b, on conversion Adobe RGB>sRGB>Adobe RGB becomes a hopeless 113r200g200b.
Those conversions are plainly unacceptable, but the conversion between RGB and CMYK are much worse. Typical CMYK lacks many colors found in any RGB, yet has others that are out of most RGB gamuts.
There are a few real-life conversions that you can do all day long, like sRGB>Adobe RGB>Apple RGB, or Apple RGB>LAB>Colormatch RGB. However, conversions like Adobe RGB>sRGB or Any RGB>Any CMYK aren't so fortunate, and often require operator intervention to restore the status quo.
>What I hope to add to this discussion, is that curves are not a color correction.
>At least not the curves in Photoshop. Curves define the sensativity of
>your recording to light, just like the curves of film. Any time you change
>curves, you are altering the exposure. This is why people will talk about
>clipping information. When you alter the exposure of your recording, you
>can only remove, you can't add.Again, this just parrots the line of those self-appointed experts who, without any pertinent experience either in color or in statistics, start spouting statistical pronouncements about color. If, for example, you start with a slightly flat, slightly muted image and use curves in LAB to open both color and contrast, this adds information to the final output by any conceivable statistical or perceptual measure.
Dan Margulis
Date: Tue, 26 Nov 2002 08:56:50 -0500
From: "john c." John Castronovo
Subject: Re: JPEG's
> Do you honor every embedded profile in files you receive from other people?As a starting point, absolutely! Especially without a proof, it's the only way of getting an idea of how the file looked to the person editing it.
As for sharing and archiving files, RGB is always best because it's smaller, has more information and is easier to re-purpose. CMYK is required for one purpose only: the printing press, and if that is your only desire, then by all means use it and throw the rest of the information away for good. To do a good job however, we shouldn't separate to CMYK without a thorough knowledge of the printing conditions including paper stock. That's not always possible, so I prefer to send tagged RGB files *and* a tagged CMYK file if I can't get the information I need. If space is the major concern (as it was in this question), I'd prefer tagged RGB to untagged CMYK, the latter being really reckless without a proof.
john castronovo
on 11/26/02 6:27 AM, Dan Margulis wrote:
> It could imply almost any number of things, granted that the people who
> coined the term "working space" almost uniformly have no real-world color
> experience, and start from the assumption that any colorspace other than RGB
> is poison.> Again, this just parrots the line of those self-appointed experts who,
> without any pertinent experience either in color or in statistics, start
> spouting statistical pronouncements about color.I wonder if Dan can ever come to the list and post useful information without slamming someone or some group in the process who he doesn1t agree with??? Dan, I1m sure you1re correct that all the people on the Adobe team are fools who have no real world experience with color and haven1t a bloody clue. I1m sure you have the statistics (again) to back this up and (again) preach to 3The Industry2 who1s worthy and who1s not. Dan, PLEASE post your stats!
This post was going well with some interesting information and everyone was getting along nicely. Dan, you really need to take an extra 3nice pill2 before posting. I know someone at Adobe were responsible for the death of your puppy but enough already! You hate them, they hate you. I suggest you simply toss that worthless piece of software (Photoshop 7) from your machine, install version 4.0 or work with Corel Paint (an application you seem to think is superior).
Andrew Rodney
Date: Tue, 26 Nov 2002 09:20:02 -0500
From: John Castronovo
Subject: Re: Re: please advise on color conversion (Ron)
> The major problem I have found is when I drop the brick on my foot.That's really funny. I'll have to remember my steel tipped boots when working in four color. It might be less painful.
Let me add that CMYK is great for some edits like using the channel mixer, but I still find it strange. Conceptually, I find it weird about CMYK that a single color can be represented many ways. That's some kind of heresy to a color scientist, no? I mean, why shouldn't every color have it's own makeup of "pure" elements? Isn't it easier? I suppose that when you're dealing with inks on press ya' gotta' do what ya' gotta' do to make it work, but we don't have to edit that way.
john castronovo
Date: Tue, 26 Nov 2002 10:04:22 -0500
From: "Derek Cooper"
Subject: RE: Re: please advise on color conversion-Can we play nice?
Morning,I have participated in this group for some time, and am disappointed to see the mud-slinging that has transpired. It's a common occurrence, and I am hoping that we can move on w/o this degenerating any further. If there are problems, the list owner can decide who is violating the guidelines for the group, and either issue a warning or in extreme cases block access.
On a cheery note, has anyone heard of or use DotWorks products? The company was brought to my attention yesterday in an unrelated discussion, but they are entirely new to me.
Cheers,
Derek Cooper
www.derekcooper.com
Date: Tue, 26 Nov 2002 07:04:13 -0800 (PST)
From: Andy Adams
Subject: Re: Re: please advise on color conversion-Can we play nice?
> I wonder if Dan can ever come to the list and post
> useful information
> without slamming someone or some group in the
> process who he doesn1t agree
> with???
>
> Andrew RodneyDan,
Just do what you always do. Every post on your part actually provides most of the real-world information I feel is useful. I learn something from everyones post, but any percieved slamming just helps all realize that no one or nothing is an ivory tower. With a little humility (and less sensitivity) we can all learn from any post and get a chuckle in the mean time.
Andy
Date: Tue, 26 Nov 2002 09:51:30 -0500
From: "john c." John Castronovo
Subject: Re: Re: please advise on color conversion
That's right Dan,In your example, the colors you've chosen are simply out of the sRGB gamut. This is why edits must be done in a wide gamut space like LAB or DonRGB. When going to a smaller gamut it's not possible to 'restore the status quo', is it? Besides adding yet another ink to improve the gamut, is there any way to restore that bright green to a reduced pallet?
john castronovo
> Yeah, provided you don't have anything resembling a bright color in the
> image. If you convert 25r250g25b, a reasonably bright green, from Adobe RGB
> to sRGB and back again, you get 141r250g59b. Having some experience with
> color-blind people, I can attest that most color-blind people could tell the
> difference between these two colors. Even a relatively subdued cyan, like
> 50r200g200b, on conversion Adobe RGB>sRGB>Adobe RGB becomes a hopeless
> 113r200g200b.
Date: Tue, 26 Nov 2002 07:35:50 -0700
From: Andrew Rodney
Subject: Re: JPEG's
John Castronovo wrote:> As for sharing and archiving files, RGB is always best because it's smaller,
> has more information and is easier to re-purpose. CMYK is required for one
> purpose only: the printing press, and if that is your only desire, then by
> all means use it and throw the rest of the information away for good.Amen brother!
> To do
> a good job however, we shouldn't separate to CMYK without a thorough
> knowledge of the printing conditions including paper stock. That's not
> always possible, so I prefer to send tagged RGB files *and* a tagged CMYK
> file if I can't get the information I need. If space is the major concern
> (as it was in this question), I'd prefer tagged RGB to untagged CMYK, the
> latter being really reckless without a proof.Again, I agree. I1ve never seen an ICC profile bigger than a meg and half and most come in at 500K or so (for output profiles; Working Space and display profiles are tiny). The space issue isn1t going to fly with me UNLESS you1re talking images for the web where we need the smallest files possible. And unless a user is running Microsoft IE 4.5 or 5.0, the web isn't1 color managed anyway (with IE it certainly is and produces previews just like good old Photoshop).
With the cost of storage and more and more digital cameras producing files starting at 18mb and going up, what1s a mere 500K? I suppose all the people that worry about file size and profiles never save layers and JPEG all their archives using 30:1 ratio. Those files and small!
Andrew Rodney
From: Andrew Rodney
Subject: Re: Re: please advise on color conversion-Can we play nice?
Derek Cooper wrote:> On a cheery note, has anyone heard of or use DotWorks products? The
> company was brought to my attention yesterday in an unrelated
> discussion, but they are entirely new to me.
Ink jet paper? I1ve tried a few different substrates and the products seem to pretty nice. I tend to stick with Epson papers since the driver is geared towards specific papers for ink delivery.Andrew Rodney
Date: Tue, 26 Nov 2002 12:19:08 -0600
From: "Maris V. Lidaka Sr."
Subject: Re: Re: please advise on color conversion-Can we play nice?
I did not read Dan's message, taken as a whole and in context rather than excerpted, as a 'slam' and hope this goes no further.Maris
----- Original Message -----
From: Andrew RodneyI wonder if Dan can ever come to the list and post useful information
without slamming someone or some group in the process who he doesn1t agree with???
Date: Tue, 26 Nov 2002 14:01:02 EST
From: Dan Margulis
Subject: Re: Re: please advise on color conversion
John Castronovo writes,>In your example, the colors you've chosen are simply out of the sRGB gamut.
>This is why edits must be done in a wide gamut space like LAB or DonRGB.The example was only in response to the incorrect assertion that it is possible to convert from Adobe RGB to sRGB "all day long." As to wide gamut spaces, they have considerable disadvantages to go along with the advantage you cite. I do frequently edit in LAB, but it isn't appropriate for all images.
>When going to a smaller gamut it's not possible to 'restore the status
>quo', is it?Sure it is, although not in that same colorspace.
>Besides adding yet another ink to improve the gamut, is there any
>way to restore that bright green to a reduced pallet?Since sRGB doesn't have inks, I have to assume you are now talking about CMYK. If you are asking, do I agree that CMYK can't construct a green that's outside the CMYK gamut, of course I do. If you are asking, does this rule out ever using such a green in a different context, no, it can easily be restored.
Date: Tue, 26 Nov 2002 13:58:17 -0800 (PST)
From: Mike Bevans
Subject: Re: Re: please advise on color conversion
I do not consider the healthy debate that my comments raised as a slam, perhaps as a misunderstanding.I trust that if people closely read the original post, I never say "convert" all day long. Nor do I ever mention converting back. Please re-read the post. I don't expect everyone to agree, but I certainly do not want to offer false information as fact.
I do take umbrage to the term "parrot" but only because I dislike birds.
-Mike Bevans
www.tribecalabs.com
Date: Tue, 26 Nov 2002 15:49:19 -0800
From: Andrew Engelhardt
Subject: RE: JPEG's
Oh man, another ICC thread. I thought Colorsync was the place for this malarkey, but since it's been brought up yet again, let me ask you a question Andrew. Have you ever worked in a high volume print production environment? Judging from your presumptuous statements about storage space and archiving files I'd assume not. The department I work in has several different "working" archives of files (as opposed to the several thousand files we must store off-line), the largest currently consisting of approx 50,000 images. On top of this we have hundreds and hundreds of other image files of varying size, type, and purpose. Let's say the average ICC profile comes in around a "mere" 700k - you do the math for just that one archive. As part of my job as the "archivist" I have to keep storage space within reasonable limits - it's not THAT cheap. Adding 500k-1.5Mb per file is not a reasonable trade-off for the amount of "useful" information an ICC profile carries which in the end will most likely be ignored anyway. I'd be better off attaching a text document to each file describing all the CMYK specs contained within. I deal with hundreds of CMYK images each week, and adding a profile is just not practical. Secondly, RGB is NOT always best for sharing or archiving files nor is it easier to re-purpose. In some cases yes, but on the whole I'd disagree with this claim. Storing files in CMYK means color-correction/contrast adjustments/out of gamut colors etc have been dealt with (or should be) - who wants to do it over and over? For these reasons alone it's easier to re-purpose a CMYK for other use. Anyway, that's just my opinion of course, but what do I know?....A. Engelhardt
Date: Tue, 26 Nov 2002 19:56:52 -0700
From: Andrew Rodney
Subject: Re: JPEG's
Andrew Engelhardt wrote:> Oh man, another ICC thread. I thought Colorsync was the place for this
> malarkey, but since it's been brought up yet again, let me ask you a
> question Andrew. Have you ever worked in a high volume print production
> environment?Lots and lots. Fortunately, for only a few days at a time. But that gives me a lot of opportunity to see lots of different setups.
> Judging from your presumptuous statements about storage space > and archiving files I'd assume not.
You1re free to make as many assumptions as you wish...
> The department I work in has several
> different "working" archives of files (as opposed to the several thousand
> files we must store off-line), the largest currently consisting of approx
> 50,000 images. On top of this we have hundreds and hundreds of other image
> files of varying size, type, and purpose. Let's say the average ICC profile
> comes in around a "mere" 700k - you do the math for just that one archive.Do you name all these files? I would assume so. An ICC profile is a color label, nothing else. IF you or someone else every needs to open that file and view it or convert it properly, you need a profile. If not, strip them out as far as I1m concerned. There are LOTS of people that work with lots of files that they need to have in a form that they can repurpose and preview multiple times throughout the file1s life. For these people, profiles are critical and the 700k is a small price to pay.
> As part of my job as the "archivist" I have to keep storage space within
> reasonable limits - it's not THAT cheap. Adding 500k-1.5Mb per file is not a
> reasonable trade-off for the amount of "useful" information an ICC profile
> carries which in the end will most likely be ignored anyway.As I1ve attempted to point out, if you don1t need to know what the file really looks like on screen or you never need to convert the file with any degree of certainly, you don1t need the profile. Lots of people don1t fall into that camp.
> I'd be better
> off attaching a text document to each file describing all the CMYK specs
> contained within.Assuming anyone would read it (in Photoshop, the profiles will be honored automatically if you set your color settings correctly). Text doc1s can be separated from the file. A profile can1t (unless someone strips it out). A text file could tell someone where to find the profile to assign. I can live with that assuming you don1t have too many files you1ll end up having to do this with.
> I deal with hundreds of CMYK images each week, and adding
> a profile is