From: Gordon Pritchard, INTERNET:gordon_pritchard@creoscitex.com
Date: Wed, Oct 3, 2001, 1:46 PM
RE: [colortheory] UCR vs GCR
Hi all,
I would like feedback on forum member's understanding of how color
separations are done in Europe, America, and Asia.I have been told that the following are representative numbers:
in Europe
- Newspaper printers use GCR of about 240
- Rotogravure use primaraly UCR of about 310 (might also be GCR)
- Commercial web offset use primaraly UCR of about 310
- sheetfed offset: usually no GCRHow does this compare with your experience?
thx, gordo
Gordon Pritchard
Commercial Print Specialist
CreoScitex
Vancouver Canada
T: 604.451.2700 ext 2870
C: 604.351.2437
gordon_pritchard@creoscitex.com
http://www.creoscitex.com>Print - dot's what it's about!<
From: Dan Margulis, INTERNET:76270.1033@compuserve.com
Date: Thu, Oct 4, 2001, 8:27 AM
RE: [colortheory] UCR vs GCR
Gordo writes,
>>I would like feedback on forum member's understanding of how color separations are done in Europe, America, and Asia. I have been told that the following are representative numbers:>>
From what I've seen there's little difference in black generation practice internationally. The same pluses and minuses apply: with a heavier black, one risks muddier images, and they're harder to correct in Photoshop. OTOH a heavier black will hold neutrality better, and also make it easier to print the job in register, or rather make a misregistered job look more acceptable.
Photoshop's "UCR" setting produces a lighter, higher-contrast black than its "Light GCR", but for printing purposes I think there is little practical difference. "Medium" or "Heavy" GCR would change the process, in some ways for better and in some ways for worse.
Although there are some people who swear by one method or another, the truth is that it doesn't make that much overall difference *unless* one is making decisions image-by-image, in which case it can be a big deal.
Printers who insist on one method or another generally are completely out of touch. Right now, their clients can be divided into those who know what they're doing, in which case they are probably using a skeleton black, and those who don't, who are probably using the Photoshop default of a heavier black. Yet from time to time both groups get good results.
>>in Europe - Newspaper printers use GCR of about 240>>
The 240 is a total ink limit, having nothing to do with one's GCR decision. 240 is also pretty standard in the U.S. Because newspaper black isn't as rich as elsewhere, and because registration problems are common in newspapers, there is a school of thought that believes in relatively heavy GCR, although I don't think it's the majority.
>>- Rotogravure use primaraly UCR of about 310 (might also be GCR)>>
That 310 should be a *minimum*, not maximum shadow. There is no upper ink limit in gravure. A very light black is certainly traditional in gravure but I don't really understand why. The two main drawbacks to using more black in offset don't apply. Large solid or semi-solid inked areas don't automatically create higher densities elsewhere, as they do in offset. Also, a major cause of excessive black inking in offset is a desire to make the type more readable. In gravure, which is ordinarily CMYKK, that objection doesn't apply because the type is on a separate cylinder from the images.
>>- Commercial web offset use primaraly UCR of about 310>>
310 is a reasonable limit although somewhat higher than in the United States. Again, the more knowledgeable users are generally using a light black but they're probably not in the majority.
>>- sheetfed offset: usually no GCR>>
Here is the only area where I think there may be a difference. A lot of European printing features an *extremely* short black. If you have access to any Heidelberg software for separating, you'll see an example. Shadow value in such a method is likely to be on the order of 98c88m88y65k, whereas in the U.S. you'd be more likely to encounter 85c75m75y80k.
Dan Margulis
From: Gordon Pritchard, INTERNET:gordon_pritchard@creoscitex.com
Date: Thu, Oct 4, 2001, 2:27 PM
RE: RE: [colortheory] UCR vs GCR
What about % of usage rather than how it is done?
What percentage of US sheetfed printers use UCR for their separations as opposed to GCR?
What percentage of US web publication printers use UCR for their separations as opposed to GCR?
How does that usage compare to Europe and Asia?
thx
Gordon Pritchard
Commercial Print Specialist
CreoScitex
Vancouver Canada
T: 604.451.2700 ext 2870
C: 604.351.2437
gordon_pritchard@creoscitex.com
http://www.creoscitex.com>Print - dot's what it's about!<
From: Dan Margulis
Date: Fri, Oct 5, 2001, 11:04 AM
RE: RE: [colortheory] UCR vs GCR
Gordo writes,
>>What about % of usage rather than how it is done?>>
I doubt that anyone has reliable information on this. You may in fact be the first person in the history of the world who has ever asked this question.
>>What percentage of US sheetfed printers use UCR for their separations as opposed to GCR?>>
In the US I don't even know what the percentage would be of printers who do their own seps. I would guess that this might be higher for sheetfed than for web.
We also fall victim to a terminology trap here--there's no real agreement on what constitutes a "UCR" sep, other than that it's a subset of "GCR". I usually employ what Photoshop calls "Light GCR", but if pressed, I would describe this as being a "skeleton black", not "GCR". Other people might disagree.
I suspect that the answer probably depends on how many printers use expensive scanners and scan directly into CMYK. If so, they're almost certainly going with the manufacturer's default, which is ordinarily a light black, UCR style, but Scitex products will produce a darker black than Screen products which in turn produce a darker black than anything from Heidelberg/Linotype/Hell. If they're using Photoshop to make the seps, odds are that they're going with a heavier GCR, because most printers don't know much about the topic--the knowledge, if anywhere, is in prepress, and it's fairly rare there.
>>What percentage of US web publication printers use UCR for their separations as opposed to GCR?>>
Probably the most telling point here is that SWOP itself, the nominal standard-setting organization for publication printing, is close to clueless about GCR. Rather than just use the Photoshop terminology, here's what they have to say:
"Current recommendations suggest that a safe range of GCR to use is between 30% and 60%. A 50% GCR setting removes 50% of the gray component normally produced by the chromatic color and compensates by adding an equivalent amount of black."
This naive description is roughly equivalent to me telling you that I would like to meet you at 2 p.m. today on the corner of First and Main, without telling you in what city. Any sane method of GCR will use a relatively low percentage of black in light grays and a relatively high one in darker grays. The SWOP definition is meaningless, worthless. And if SWOP doesn't know what it's talking about, how can we expect the individual web printers to?
Dan Margulis
From: "Kauffman, Terry G", INTERNET:Terry.Kauffman@usa.xerox.com
Date: Fri, Oct 5, 2001, 7:36 PM
RE: RE: [colortheory] UCR vs GCR
Dan,
Would the CMM used for the conversion have a significant impact on the black plate? In a recent article discussing CMMs it appeared that Imation had the superior technology because they maintained an excellent black channel. I've attached the article and would like your opinion. I work for Xerox and we sell their server attached to a DocuColor 12 printer and the results we get are unbelievable. We have shown this product to several high profile service bureaus and companies and they cannot believe the quality from a xerographic device.
From: INTERNET:samarsh@ozemail.com.au, INTERNET:samarsh@ozemail.com.au
Date: Fri, Oct 5, 2001, 10:56 PM
RE: [colortheory] Re: UCR vs GCR...or Neither - RAW CMYK?
Dan writes:
> I suspect that the answer probably depends on how many printers use
> expensive scanners and scan directly into CMYK. If so, they're almost
> certainly going with the manufacturer's default, which is ordinarily a
> light black, UCR style, but Scitex products will produce a darker black
> than Screen products which in turn produce a darker black than anything
> from Heidelberg/Linotype/Hell. If they're using Photoshop to make the seps,
> odds are that they're going with a heavier GCR, because most printers don't
> know much about the topic--the knowledge, if anywhere, is in prepress, and
> it's fairly rare there.Dan, this is a good opening for bringing up a subject which has been bugging me for a while.
I use one of those expensive Scitex scanners you mention - and I would have to agree with your take on their default tables black generation. I have not been able to make a custom black generation curve in Photoshop that even comes close.
In part this is due to how hard the black generation curve is to edit - and that Photoshop _only_ gives the option of UCR or GCR separation methods.
To mimick the defualt scanner sep, I would need to make two Photoshop conversions, one using CMY only and another to make a custom black plate to plug into the CMY file!
The Scitex scanner in default CMYK tables settings scans into CMYK with GCR and UCR turned OFF. You get 'raw' CMYK.
By evaluating the separation setup curves in the scanner for the off setting - one can get a basic understanding of the process.
It seems that CMY are used throughout the image to describe neutral tones. I guess this is similar to using GCR with no black generation. This is the closest description to the CMY behaviour that I can come up with, and is not a good example.
Black curve seems to start at around 40% and seems irrelevant to the 'linear' neutral CMY curve (where cyan is run higher).
Shadow aimpoints are very high in all four colours, often delivering TAC of 360%.
This is out of my 'desktop' experience and must be a throwback to more traditional scanning or separation. This 'raw' CMYK is very different to Photoshops UCR or GCR separations.
Basically - there seems to be no way to make the built in settings of Photoshop behave in a similar way - since UCR or GCR is always in use for a separation.
Now back to UCR or GCR.
The Scitex software does use the % term for GCR. There is no mention of none, light, medium, heavy or maximum black generation - as in Photoshop.
As a side note - my 'antique' copy of Macromedia xRes had a similar approach.
The conversion from RGB to CMYK was 'raw'. After the file was in CMYK, then the UCR/GCR command was run...you could even apply this command to a CMYK file created in other software.
A dialog box was presented with the choice of UCR or GCR and their related controls, including start point for the grey component, black limit, TAC and percent of UCR or GCR (with UCA as an option as well).
All this was applied as a post separation move - instead of during separation...which seems weird to my Photoshop experience, but it may have some uses. I have not kicked these options around much - since xRes gathers actual and virtual dust.
As for your comment on the knowledge being is pre press, and that it is usually lacking - I have to agree.
Before reading your works, I used GCR med black generation as a general rule - but did experiment with light black generation.
Now I use GCR light black or UCR most of the time, unless more black can help (when doing Photoshop seps). This is very much an individual image and output based decision - gone are the days when one setting suited all (now that I know better). I have not reached this level on the scanner yet.
But most users that I have seen use GCR Med and the other defaults in Photoshops built in settings as a standard - if they are not using a profile such as SWOP v2 or US Flatsheet v2 etc.
> Rather than just use the Photoshop terminology, here's
> what they have to say:
>
> "Current recommendations suggest that a safe range of GCR to use is between
> 30% and 60%. A 50% GCR setting removes 50% of the gray component normally
> produced by the chromatic color and compensates by adding an equivalent
> amount of black."
> > This naive description is roughly equivalent to me telling you that I would
> like to meet you at 2 p.m. today on the corner of First and Main, without
> telling you in what city. Any sane method of GCR will use a relatively low
> percentage of black in light greys and a relatively high one in darker
> greys. The SWOP definition is meaningless, worthless. And if SWOP doesn't
> know what it's talking about, how can we expect the individual web printers
> to?Well, if using xRes then I guess I would enter 50% as the percentage of UCR or GCR - with a start point of around 25%. It seems that xRes does work this way - there are no light, medium, heavy or max options.
The same for my Scitex separation method - if GCR is chosen then you have no choice but to enter a percentage value for UCR or GCR, and a black start point %, black limits, TAC etc.
Dot gain is never explicityly mentioned in the scanner software.
But since xRes is history, then the question is a lot harder for Photoshop - which does not use these terms. Instead we have UCR, or GCR - none (cmy) light, med, heavy and max black generation.
But from what you are saying, knowing the amount of UCR or GCR is pointless without knowing the black generation method, as in the start point for black?
I take it that the black start point in more traditional separation software is what Photoshops named black generation settings do, or perhaps the custom black generation curve option?
I thought that the use of the term 50% GCR was an old drum scanner or traditional separation terminology. Since I entered pre press through typesetting - I just presumed that this was a gap in my knowledge, that would have been covered if I originally trained in repro instead of type.
Many printers still list this in their separation spec sheets - instead of the more 'regular' or 'standard' Photoshop terminology. But just like SWOP, they do not mention a start point - only the amount of UCR or GCR.
As for the original post - I work for an Australian commercial printer and we will take pretty much any separation you can throw at us (for good coated stock). We use CTP and only have one four colour flatsheet litho press - so things are pretty tight in process control. Before working here, I would have considered the seps we produce mud - but everyone seems happy...
I am glad that I am not the only one having problems understanding all this...I thought it was just me. [g]
Regards,
Stephen Marsh.
From: Dan Margulis, INTERNET:76270.1033@compuserve.com
Date: Sat, Oct 6, 2001, 3:03 PM
RE: [colortheory] Re: UCR vs GCR...or Neither - RAW CMYK?
Stephen writes,
>>I use one of those expensive Scitex scanners you mention - and I would have to agree with your take on their default tables black generation. I have not been able to make a custom black generation curve in Photoshop that even comes close.>>
The question is why you would want to. The whole point of variant black generations is that theoretically the colors remain the same--in principle Heavy GCR gives the same result in print as UCR. In practice it doesn't, but the difference between Photoshop's Light GCR and Scitex's is going to be very small in the overall scheme of things.
>>In part this is due to how hard the black generation curve is to edit - and that Photoshop _only_ gives the option of UCR or GCR separation methods.>>
*All* separations, saving those that are CMY only, are UCR or GCR.
>>The Scitex scanner in default CMYK tables settings scans into CMYK with GCR and UCR turned OFF. You get 'raw' CMYK.>>
There isn't any such animal. The scanner records R,G, and B data which becomes, with mild variation, C, M, and Y. The black data is calculated from the other three--there are no CMYK-native scanners.
>>It seems that CMY are used throughout the image to describe neutral tones. I guess this is similar to using GCR with no black generation.>>
No, this is traditional UCR, black only appearing where necessary to achieve darkness, not to hold neutrality.
>>Now I use GCR light black or UCR most of the time, unless more black can help (when doing Photoshop seps). This is very much an individual image and output based decision - gone are the days when one setting suited all (now that I know better). I have not reached this level on the scanner yet.>>
Your policy is a good one, but I doubt that it's worth worrying about extending it to the scanner. When you run across something that needs a nonstandard black, do it in Photoshop-it's a lot easier. Four years ago, in reviewing the new Scitex line, I wrote:
"Basic scanning may be easy, but the exceptions are lethal. Scitex's has several sets of preset CMYK parameters for different printing conditions--but, unbelievably, none for the most common of all, SWOP. Users can create these parameters for themselves--if they happen to be one of the twenty or so individuals on the planet capable of figuring out Scitex's exceedingly opaque implementation of black generation."
>>Dot gain is never explicitly mentioned in the scanner software.>>
Dot gain and black generation are different animals. If you believe that an image will correct or print better with a higher black component, that decision would presumably the same on either 100# Kromekote or newsprint.
>>But from what you are saying, knowing the amount of UCR or GCR is pointless without knowing the black generation method, as in the start point for black?>>
In order to conceptualize the kind of black that's being generated one needs to know the start point of the black and the how the slope of the curve varies. A percentage is only going to be relevant at one point on the curve. In darker areas, the percentage of black will be higher and in lighter areas it will be lower.
>>I thought that the use of the term 50% GCR was an old drum scanner or traditional separation terminology.>>
It's sort of like the percentages used in the "Amount" field of the Unsharp Mask filter or the dot gain percentage in CMYK setup. The user doesn't need to know what the percentages mean, just that a higher percentage increases the effect. Unlike these two, however, which *do* have meanings that an interested user could find out, "50% GCR" is meaningless without further explanation, except that it probably generates less black than 60% GCR.
>>Many printers still list this in their separation spec sheets - instead of the more 'regular' or 'standard' Photoshop terminology. But just like SWOP, they do not mention a start point -- only the amount of UCR or GCR.>>
Sure, and many others express their column width in pica ems, or indicate that they have 2% dot gain.
Dan Margulis
From: INTERNET:samarsh@ozemail.com.au, INTERNET:samarsh@ozemail.com.au
Date: Mon, Oct 8, 2001, 3:34 AM
RE: [colortheory] Re: UCR vs GCR - So RAW is really UCR...
--- In colortheory@y..., Dan Margulis<76270.1033@c...>wrote:
> There isn't any such animal. The scanner records R,G, and B data which
> becomes, with mild variation, C, M, and Y. The black data is calculated
> from the other three.Thanks Dan. It was a shock to me to find that you could turn UCR and GCR functions off for the CMYK conversion...I took the setting at 'face value' (silly me).
Then I blew the dust off Macromedia xRes and it had similar features.
As Photoshop is my major experience...I did not know what was going on.
So I take it that you are saying that even though UCR is off - this is still a UCR sep, just different to Photoshops flavour.
You gotta love CreoScitex - UCR/GCR off is still UCR. So there must be a difference between the active UCR settings and the off setting...perhaps one year I will have time to play and see.
> No, this is traditional UCR, black only appearing where necessary to
> achieve darkness, not to hold neutrality.
>What was throwing me was that there is no 'cross over' on the gray ramp where the CMY and K plates interact in the threequarter tones and shadow, as in Photoshop.
The scitex gray ramp looks so 'alien' when UCR/GCR is off...that I thought that something else was going on. When these functions are on, the ramps look closer to Photoshop - but they have very different defaults with steeper curves etc.
> Sure, and many others express their column width in pica ems, or indicate
> that they have 2% dot gain.
>Chuckling...
Thank's for your time and thoughts Dan - as ever your words leave me smiling.
Regards,
Stephen Marsh.
From: Dave Badger, INTERNET:dbadge@worldnet.att.net
Date: Sun, Oct 7, 2001, 9:41 PM
RE: Re: [colortheory] Re: UCR vs GCR...or Neither - RAW CMYK?
on 10/6/01 3:00 PM, Dan Margulis wrote:
> Dot gain and black generation are different animals. If you believe that an
> image will correct or print better with a higher black component, that
> decision would presumably the same on either 100# Kromekote or newsprint.I have been using Photoshop's Medium Generation for a long time now because GCR is supposed to give you better saturation and depth in the darker colors. I believe this to be true and think that, for example, cyan in reds being replaced partially by black is a good thing. Yet no black substitution take place in lighter skin tones, so the start point of this setting seems fine.
Using this setting means the black is more critical on press, so I would think using UCR or Light GCR would be better for newsprint since their black plate would be less controlled or more dot gain.
> Printers who insist on one method or another generally are completely out > of touch. Right now, their clients can be divided into those who know what > they're doing, in which case they are probably using a skeleton black, and > those who don't, who are probably using the Photoshop default of a heavier > black. Yet from time to time both groups get good results.
This statement seems to indicate that people who use Photoshop's Medium GCR setting are unsophisticated users. Yet you've said one form of UCR/GCR is not necessarily better then another.
> The same pluses and minuses apply: with a heavier black, > one risks muddier images, and they're harder to correct in Photoshop. OTOH > a heavier black will hold neutrality better, and also make it easier to > print the job in register, or rather make a misregistered job look more > acceptable.
Can you further explain why you favor a skeleton black and are there any other downsides to GCR then those you listed above?
Dave Badger
From: INTERNET:samarsh@ozemail.com.au, INTERNET:samarsh@ozemail.com.au
Date: Mon, Oct 8, 2001, 4:09 AM
RE: Scanner Training Advice (was: UCR vs GCR...or Neither - RAW CMYK?)
Dan, once again - thank you for your time and knowledge.
I am sending this mail to you off list - in case it is not appropriate for the list. Please feel free to forward this to the ACT list if it is for general consumption.
======
Dan writes:
> Four years ago, in
> reviewing the new Scitex line, I wrote:
>
> "Basic scanning may be easy, but the exceptions are lethal. Scitex's has
> several sets of preset CMYK parameters for different printing
> conditions--but, unbelievably, none for the most common of all, SWOP. Users
> can create these parameters for themselves--if they happen to be one of the
> twenty or so individuals on the planet capable of figuring out Scitex's
> exceedingly opaque implementation of black generation."
>Dan, I have checked out the archives at Electronic Publishing for EverSmart Supreme articles but found nothing with any 'meat' and nothing written by you.
Do you have any links or archives of the reviews or articles you have written on these scanners or related software (oXYgen)?
Now for the real question...
Our newish scanner still has some 'free' training that came with it - that the main pre press guy did not need (experienced scanner op). Lucky for me - I am being offered the short CreoScitex training, which from all reports is worth a quite a bit of money (if it did not come with the scanner).
I would like to make the best of this oportunity - but have not had access to this type of training before.
I have no real high end scanning experience, but am comfortable with a scanner, Photoshop and by the numbers workflows.
I was wondering if you and perhaps the list have any thoughts on how I could maximise the training. I know many on this list attend specific training or seminars - are there any tips from all those people who have 'been there - done that'.
If this is a standard 'abc123' taining course - then there might not be too much room to ask questions or to get into the deeper aspects, which may be beyond the simple training session.
From what I have read on one old message list - the training is focused on CMYK table or device link scanning, with the ICC and DT/SOOM workflows pretty much ignored. As I am in pre press for a traditional printer - this does not seem to be a problem (they would probably ask for this anyway).
Any thoughts or links would be greatly appreciated. I have considered posting this on the Scan-Hi End list - but I respect the opinions of this list and will hold off on any cross posts until the issue is well and dead.
Sincerely,
Stephen Marsh.
From: "Ruud", INTERNET:ludwig@xs4all.nl
Date: Mon, Oct 8, 2001, 4:37 PM
RE: [colortheory] Re: UCR vs GCR
Dan Margulis wrote
>>We also fall victim to a terminology trap here--there's no real agreement on what constitutes a "UCR" sep, other than that it's a subset of "GCR".
You're right. IMO the terminology went wrong when vendors started to make their own definitions. I worked with the old Magnascanners from Crosfield. There I could choose between UCR and PCR or a combination of those two.
UCR = Under Color Removal
PCR = Poly Color Removal
The difference between those two was that UCR was only active in the neutrals and PCR in the colors. But PCR was in fact the same as the german definition 'unbunt' on the Hell scanners or the American GCA (Gray Component Addition) and it's opponent GCR.So UCR and GCR both mean the same and are active in the neutrals (the L axis in Lab). PCR, unbunt and GCA are also the same and use the combination of all three axis in Lab.
Excuse my English, I seem to have a Dutch accent.
Ruud de Korte
From: "Ruud", INTERNET:ludwig@xs4all.nl
Date: Mon, Oct 8, 2001, 4:37 PM
RE: [colortheory] Re: UCR vs GCR
Oops, too fast..
I wrote
>>But PCR was in fact the same as the german definition 'unbunt' on the Hell scanners or the American GCA (Gray Component Addition) and it's opponent GCR.Last thing was wrong, GCR has nothing to do with GCA, it's the same as UCR, I shouldn't mention it in that sentence.
Ruud de Korte
From: Dan Margulis, INTERNET:76270.1033@compuserve.com
Date: Mon, Oct 8, 2001, 8:25 PM
RE: [colortheory] Scanning Class information??
This individual has previously taken my ACT course.
Dan Margulis
--------------- Forwarded Message ---------------
To: Dan Margulis, 76270,1033
Date: Mon, Oct 8, 2001, 3:24 PMRE: Class information
Dear Dan,Although I have been following all threads with interest, I don't think this note would be of interest to the discussion group. Having never posted anything anywhere online before (just shy I guess) I am working on the assumption that this question is too specific for the group.
I have been seeking out a scanner operator class with no luck (all that I found are on-site and product-specific classes). I did find one in the UK but being on the west coast, that's a little further than I care to travel. I have not seen any such course offered by Sterling-Ledet but am assuming such information is available to them. I'm hoping for a more general (if possible) class, and since I am not currently working, "on-site" is not an option. Hopefully with a class of this type added to my resume the dry market might dampen up.
Anyway, noticing a new thread in the discussion group as well as your standing in the education field, I thought I might inquire as to your knowledge of the availability of any such courses. Any information and/or recommendations of such courses would be appreciated.
Regards,
From: Dan Margulis, INTERNET:76270.1033@compuserve.com
Date: Mon, Oct 8, 2001, 8:24 PM
RE: Re: [colortheory] Re: UCR vs GCR...or Neither - RAW CMYK?
Dave Badger writes,
>>I have been using Photoshop's Medium Generation for a long time now because GCR is supposed to give you better saturation and depth in the darker colors. I believe this to be true and think that, for example, cyan in reds being replaced partially by black is a good thing.>>
I would think the opposite would be true. In principle the two results should be the same. In practice, black is much stronger than cyan is, so any variance in inking would create a color issue, especially since the dominant magenta and yellow in the reds will have been reduced to accommodate the black.
>>Using this setting means the black is more critical on press, so I would think using UCR or Light GCR would be better for newsprint since their black plate would be less controlled or more dot gain.>>
Certainly inking generally is less in control in newspaper printing. However, 1) the black ink used on newsprint isn't as powerful as in commercial printing, therefore the impact of a density change isn't as severe; 2) in commercial printing, if the black runs too heavily one of the principal suspects always is that the pressman was attempting to compensate for small type or type that is difficult to print because of thinness in part of the strokes, such as Bodoni, Baskerville, or to a lesser extent, Times Roman. Newspapers generally aren't subject to this effect because their text face is invariably something like Excelsior or Ionic or Times Europa that is specifically designed for legibility at the expense of aesthetics.
So, while I'd agree with the general policy of using a skeleton black in newspapers, I think there's more of a case for using a heavier black than there is in other forms of offset.
>>This statement seems to indicate that people who use Photoshop's Medium GCR setting are unsophisticated users. Yet you've said one form of UCR/GCR is not necessarily better then another.>>
Those experienced in preparing images for CMYK, especially if the target is a press, by and large certainly favor a lighter black than the Photoshop default. One form of black generation isn't necessarily better, except in an image-by-image context, and except in the context of how variable one expectst the output device to be. A lot of the reasons for preferring a lighter black vanish if the output is going to be inkjet rather than press.
>>Can you further explain why you favor a skeleton black and are there any other downsides to GCR then those you listed above?>>
In addition to the issues mentioned earlier, the services of our friends in the color management community become more important if you're using a heavier black. Photoshop makes the wrong assumption that black has the same dot gain as the other inks, whereas in real life it's usually higher. But it's very much case by case, so a lot of users have incorrect black dot gain values unless they've really gone to a lot of effort.
If you are using a skeleton black and your black dot gain value is too low, this isn't great but it isn't a tragedy. If you're using a heavier black that affects colored areas, you're really risking a muddy sep.
Dan Margulis
From: Martin Orpen, INTERNET:orpy@idea-digital.com
Date: Tue, Oct 9, 2001, 5:47 AM
RE: Re: [colortheory] Scanner Training Advice (was: UCR vs GCR...or Neither - RAW CMYK?)
> I was wondering if you and perhaps the list have any thoughts on
> how I could maximise the training. I know many on this list attend
> specific training or seminars - are there any tips from all those
> people who have 'been there - done that'.I have no experience of CreoScitex training (apart from LeafCapture on the Volare camera). However, I have been to a number of scanner demos and would offer the following advice:
Take your own originals rather than allowing the demonstrators to use their own standard demonstration images. This will enable you to see how the demonstrator copes with an image from scratch rather than have them rattle through a set routine that they have no doubt done hundreds of times before.
Make sure that your originals are tough scanning propositions, for example:
1. An *arty* image that has no natural looking highlight, shadow or gray midtones. One that has been shot using coloured gels with vibrant RGB colours. This should demonstrate how well the demonstrator can cope with numbers only -- or whether the scanning software has profiles for standard film stocks.
2. A tranny that has had a hard life. See how the demonstrators cope with scratched and pitted originals. If the demo is on drum scanners then oil mounting will fill in most of the damage. If it's on a flatbed is it still possible to oil mount?
3. Under- and over-exposed transparencies. Take one of each and see how the demonstrator and scanner hardware cope with pulling out shadow and highlight detail.
4. Black and white prints. Take one of these along as a test of the scanner's light source. Some scanners have real problems with dust and surface imperfections on prints. You can do the scan in 5 minutes, but then have to spend an hour removing the blemishes.
5. A negative. Don't know what CreoScitex's position on negative is? Most conventional repro houses refuse to go anywhere near them. If the software is able to produce positives from neg, watch the adjustments that the demonstrator carries out.
Large format negatives and positives are also ideal for spotting deficiencies on CCD scanners. In particular, check for banding artefacts in blue skies or red sunsets. If you see these, then you know that your scanner is using Kodak's last generation of 10K CCD chips. The banding is caused by connecting wires which run beneath the red and blue colour filters. Kodak recently redesigned their CCDs -- but most scanner manufacturers are still using stockpiles of the older model.
While your originals are being scanned, take a detailed look at the USM functions of the scanner software. Scanner USM is usually far superior to Photoshop. However, this usually leads to a fairly complicated interface that you tend to forget after the demo and switch to "auto" when you get back to the shop :-)
Likewise, with the separation settings, the scanner manufacturers usually tell you that profile x is best for this and profile y for that. Get as much information on the profiles as you can. Find out how easy it is to edit the CMYK profiles and whether the same profiles can be used in Photoshop.
That should be plenty for one day!
-- Martin
Idea Digital Imaging Ltd - the "image" specialists
http://www.idea-digital.com
From: INTERNET:samarsh@ozemail.com.au, INTERNET:samarsh@ozemail.com.au
Date: Tue, Oct 9, 2001, 8:41 AM
RE: [colortheory] Re: Scanning Class information??
> I have been seeking out a scanner operator class with no luck (all
> that I found are on-site and product-specific classes). I did find one in
> the UK but being on the west coast, that's a little further than I care to
> travel. I have not seen any such course offered by Sterling-Ledet but am
> assuming such information is available to them. I'm hoping for a more
> general (if possible) class, and since I am not currently working,
> "on-site" is not an option. Hopefully with a class of this type added to my
> resume the dry market might dampen up.If you have attended one of Dan's colour correction workshops - then I presume that you are at a certain level of experience in pre press or photography etc. One would not presume that you are rank amateur (unless you had generous employers or some spare money to throw around).
This should be a good thing to note on the resume.
Now I guess that you are not referring to traditional horizontal PMT drum scanning.
In Australia, graphic repro apprentices specialised in this field and learned the craft over a four year period - from experienced and knowledgeable tradespersons.
If you are talking of high to medium end flatbed scanning, then this would not require the same sort of background.
There is not much in the hardware side to learn. Cleaning originals is not rocket science. Mounting originals is usually very straight forward as well. Some flatbeds have oil mounts, and I have heard of some custom hacks as well - but this is not the norm for most flatbed users. Oil/gel mounting is messy and requires more time and work, but the results are probably worth it...when I think of how much spotting time this removes - not to mention much better transmissive scans.
What is left is learning the controls of the scanners software and how they apply to various originals etc - and how to edit by the numbers or visually with ICC or other methods.
So without devaluating the whole art of scanning too much - if you are proficient with Photoshop, RGB, LAB and CMYK editing and have broad production experience in print or imaging etc, then most of the learning curve is probably covered.
It would depend on the setting you were aiming for...
A traditional by the numbers scanner operator whose main concern is CMYK and print is one type user employers are after.
An ICC fluent operator who knows RGB and colour management and scans raw, flat untoned high bit images for high bit editing in Photoshop for archival is another position.
Even though both are scanner operators - they have very different outlooks and experience. This is not to say that they are mutually exclusive.
Since clients do their own scans these days - professional scanning is more a side issue, for most shops.
As you rightly state - another skill can be a big asset to your employability.
If my hunch is right about your experience, you are probably most of the way there now - even if you have not used a scanner.
I can supply some links off list if you would like, which may be of help.
Regards,
Stephen Marsh.
From: INTERNET:samarsh@ozemail.com.au, INTERNET:samarsh@ozemail.com.au
Date: Tue, Oct 9, 2001, 8:40 AM
RE: [colortheory] Re: Scanner Training Advice (was: UCR vs GCR...or Neither - RAW CMYK?)
I originally wrote:
> > I was wondering if you and perhaps the list have any thoughts on
> > how I could maximise the training. I know many on this list attend
> > specific training or seminars - are there any tips from all those
> > people who have 'been there - done that'.
>Martin replied:
> I have no experience of CreoScitex training (apart from LeafCapture on the
> Volare camera). However, I have been to a number of scanner demos and would
> offer the following advice:Thanks for the reply Martin. So, did the LEAF training simply take you through the printed exercise book, using the half dozen or so examples or whatever?
I have a gut feeling that my training will not be too extreme.
>
> Take your own originals rather than allowing the demonstrators to use their
> own standard demonstration images. This will enable you to see how the
> demonstrator copes with an image from scratch rather than have them rattle
> through a set routine that they have no doubt done hundreds of times before.
>Very good point.
The scanner comes with some exercise originals...
Trannys, negs, colour reflective, BW ref, Halftone print.
I presume that these will be used, in conjunction with the exercises which I have used in the manual anyway...but I will see on the day I guess.
> Make sure that your originals are tough scanning propositions, for example:
>
> 1. An *arty* image that has no natural looking highlight, shadow or gray
> midtones. One that has been shot using coloured gels with vibrant RGB
> colours. This should demonstrate how well the demonstrator can cope with
> numbers only -- or whether the scanning software has profiles for standard
> film stocks.Yes this is a good test, and all the supplied scanner exercise images do have endpoints...
>
> 2. A tranny that has had a hard life. See how the demonstrators cope with
> scratched and pitted originals. If the demo is on drum scanners then oil
> mounting will fill in most of the damage. If it's on a flatbed is it still
> possible to oil mount?The EverSmart Supreme can oil mount - but this is optional.
CreoScitex also offer an optional Photoshop plug to help automate dust/scratch removal.
But this would be very good to see, since this scanner seems very unforgiving of originals quality (also the six surfaces in scanning trans can be a real dust spotting problem).
> > 3. Under- and over-exposed transparencies. Take one of each and see how the
> demonstrator and scanner hardware cope with pulling out shadow and highlight
> detail.The range of this scanner is very good, not drum but very very good.
> 4. Black and white prints. Take one of these along as a test of the
> scanner's light source.Are you referring to native scanner RGB grey balance?
I did a test using a Kodak Greyscale - and each patch was within one or two RGB points of each other, all over the scale. This scanner, with nothing more than a canned profile - is near grey linear balanced. It is so close to R=G=B - but you expect that for the insane price tag!
> > 5. A negative. Don't know what CreoScitex's position on negative is? Most
> conventional repro houses refuse to go anywhere near them. If the software
> is able to produce positives from neg, watch the adjustments that the
> demonstrator carries out.It's a bit like getting a poor RGB, with no profile. Most repro places would not like to go near these too!
The scanner has various neg tables for filmtype makes/models - and this may help up to a point, but is not a holy grail (too many variables for canned profiles).
It is all memory colours.
This is a strength of CMYK by the numbers editing.
I will attempt to push for this, as I have not got around to playing with the supplied exercise neg yet. I have inverted/removed the orange mask before using Photoshop - but not in the scanner, on raw data before the image is finally acquired.
> > While your originals are being scanned, take a detailed look at the USM
> functions of the scanner software. Scanner USM is usually far superior to
> Photoshop. However, this usually leads to a fairly complicated interface
> that you tend to forget after the demo and switch to "auto" when you get
> back to the shop :-)
>The controls for USM are very good, and you can even use filters in the scan.
The big drawback is that the scanner does not do this on a live interactive way.
You change the setting, then perform a new hi res prescan of the selected area.
Each time you check a new area of the image, its a new 'max detail' scan. This can take about 30 seconds just to evaluate the USM.
Dan wrote to me that Photoshop is better. Now I understand what he meant.
No matter how many options, or how good the tool - if it is hard or impractical to use, the results may be poorer than Photoshops 'poor' USM.
> Likewise, with the separation settings, the scanner manufacturers usually
> tell you that profile x is best for this and profile y for that. Get as much
> information on the profiles as you can. Find out how easy it is to edit the
> CMYK profiles and whether the same profiles can be used in Photoshop.
>It is my guess that the basic CMYK table will be used.
I will PUSH for an explanation of their crazy OFF/UCR/GCR function.
There is a weird table called 'LUT.id' which I cant find any mention of - but I presume it is something to do with calibration.
All other files are true ICC profiles for input/output.
There are also 'device link profiles' which are a proprietary combination of tables/profiles/scanner settings which are presaved into a 'profile'.
This does not seem to be a true ICC profile - but a proprietary one.
It is my guess that ICC scanning, RGB output and the tabled DT/SOOM will be ignored...but again I will shortly see this for myself.
> That should be plenty for one day!
Martin, you have helped me more than you can know - and with luck others as well. Cheers!
Stephen Marsh.
From: Dan Margulis, INTERNET:76270.1033@compuserve.com
Date: Tue, Oct 9, 2001, 9:22 AM
RE: [colortheory] Scanner Training Advice (was: UCR vs GCR...or Neither - RAW CMYK?)
Stephen writes,
>>I was wondering if you and perhaps the list have any thoughts on how I could maximise the training. I know many on this list attend specific training or seminars - are there any tips from all those people who have 'been there - done that'.>>
As one who's been to a *lot* of scanner training, let me suggest that everything depends on the instructor. They range in my experience from highly qualified and insightful to total baboons. It's well worth your while to insist on speaking to the instructor in advance to find out what kind of person you can expect. Often you'll find that the individual has certain experience that you can really mine. If the person has been a professional scanner operator, plan on spending a lot of time discussing techniques for specific originals, but don't expect more than a book recitation of what the conversion software does. Similarly if the person is a software geek you may be able to go in depth in that area. And if your impression is that the instructor is as dumb as a sack of rocks, just go with a fixed itinerary of things you need to see and hope for the best.
Also: re the forwarded question about open-to-the-public scanner training: I'm not aware of that kind of training being available anywhere, but that doesn't mean it doesn't exist.
Dan Margulis
From: Martin Orpen, INTERNET:orpy@idea-digital.com
Date: Tue, Oct 9, 2001, 9:29 AM
RE: Re: [colortheory] Re: Scanner Training Advice (was: UCR vs GCR...or Neither - RAW CMYK?)
on 9/10/01 1:39 pm, samarsh@ozemail.com.au at samarsh@ozemail.com.au wrote:
>> 4. Black and white prints. Take one of these along as a test of
> the
>> scanner's light source.
> > Are you referring to native scanner RGB grey balance?Sorry, I didn't make myself very clear on this point.
The light source on the flatbeds is extremely critical when it comes to the apparent sharpness of the images. IMO the first Scitex and Scanview flatbeds produced horrible, oversharpened images. The results from photographic prints were pretty much unusable unless the USM was turned off!
The smallest specs of dust or surface imperfections were magnified, so your high quality fibre print ended up looking a real mess.
Scanview have since modified the light source to make it less focused and more diffuse -- this cured the problem.
> Each time you check a new area of the image, its a new 'max
> detail' scan. This can take about 30 seconds just to evaluate the
> USM.This is similar to our scanner -- we get a general preview that is fairly
mediocre -- but can choose to scan a portion at final resolution before
committing the whole image.Unfortunately you just have to keep a bunch of settings in your mind --
ColorQuartet allows adjustment of strength, noise, light contours, dark
contours and contour thresholds. With power comes the responsibility to
RTFM!> There is a weird table called 'LUT.id' which I cant find any
> mention of - but I presume it is something to do with calibration.Lut is a look-up-table which is probably used to display your image on
screen, or convert native Lab data to RGB.
> There are also 'device link profiles' which are a proprietary
> combination of tables/profiles/scanner settings which are
> presaved into a 'profile'.
>
> This does not seem to be a true ICC profile - but a proprietary
> one.Proprietary always bothers me -- which is why we don't buy much Scitex kit.
--
Martin
Idea Digital Imaging Ltd - the "image" specialists
http://www.idea-digital.com
From: INTERNET:samarsh@ozemail.com.au, INTERNET:samarsh@ozemail.com.au
Date: Tue, Oct 9, 2001, 11:42 AM
RE: [colortheory] Re: Scanner Training Advice
Martin replies:
> Sorry, I didn't make myself very clear on this point.
>
> The light source on the flatbeds is extremely critical when it comes to the
> apparent sharpness of the images. IMO the first Scitex and Scanview flatbeds
> produced horrible, oversharpened images. The results from photographic
> prints were pretty much unusable unless the USM was turned off!
>
> The smallest specs of dust or surface imperfections were magnified, so your
> high quality fibre print ended up looking a real mess.
>
> Scanview have since modified the light source to make it less focused and
> more diffuse -- this cured the problem.
>I don't think that things have changed, even on the top of the line model purchased less than six months ago...
The main pre press guy who does most of the scanning comes from a traditional background - USM in the scan.
As you and many others have noted, the EverSmart line have a very crisp 'print' look - even with USM off. I have to agree. Photographers who output to Lightjets or other contone devices do not like this effect, and are quite vocal on it.
For transmissive scans, this seems an advantage - but I am biased towards commercial flatsheet offset.
For transmissive, scaner USM may be OK, but if left to my own devices I would sharpen reflective prints in Photoshop.
Reflective photo prints really suffer from the USM, they look crunchy on the monitor - but it's amazing what an equalizer the halftone screen is - even at 175 lpi using CTP.
The USM control in the scanner does have a good grain control, plus there is also optical defocusing and then the red, green or red/green filter combo in the scanner...
I think I will really have to pick the CreoScitex guys brain on the extended USM functions.
>
> > Each time you check a new area of the image, its a new 'max
> > detail' scan. This can take about 30 seconds just to evaluate the
> > USM.
>
> This is similar to our scanner -- we get a general preview that is fairly
> mediocre -- but can choose to scan a portion at final resolution before
> committing the whole image.
>
> Unfortunately you just have to keep a bunch of settings in your mind --
> ColorQuartet allows adjustment of strength, noise, light contours, dark
> contours and contour thresholds. With power comes the responsibility to
> RTFM!
>Too true. Thats why it's so easy for many to stick to factory defaults.
> > There is a weird table called 'LUT.id' which I cant find any
> > mention of - but I presume it is something to do with calibration.
>
> Lut is a look-up-table which is probably used to display your image on
> screen, or convert native Lab data to RGB.
>I am familiar with LUT's, as this is our default method for acquiring CMYK (or perhaps one day the odd RGB) scans.
What I mean is that you can choose two colour modes for the scan. CMYK or perhaps RGB.
Then there are two real options for scanning into a specific space or flavour, with a third option being the device link section.
The first option, is the input/output ICC profiles. You can scan from ref/trans scanner RGB input to other output modes, or raw scanner space (with or without a tag). This is all ICC driven.
The second option is to use the default RGB or CMYK table option for separation or colour description. The input is the default ref/trans RGB input description. This is the old style format, proprietary CLUT approach. It is also used for the non ICC Scitex monitor calibration/colour matching tool - since these tables are out of the ICC softproofing link.This 'table' section has the second option with the lable 'LUT.id'.
I recall reading somewhere online, but cant find where - that this is used in ICC scanning or something...either IT8 scanning or perhaps raw untoned high bit editing.
Either way, it probably is not a concern for us.
This LUT.id provides a very flat, untoned image. But I guess it has a use - I can sleep till I find out on the training day.
>
> > There are also 'device link profiles' which are a proprietary
> > combination of tables/profiles/scanner settings which are
> > presaved into a 'profile'.
> > > > This does not seem to be a true ICC profile - but a proprietary
> > one.
>
> Proprietory always bothers me -- which is why we don't buy much Scitex kit.
>This is true, up to a point - but I think times are changing. Perhpas the Lino approach is giving them some competition.
The eversmart uses LS or luminance/saturation curves - but LAB is not an option that I know of - even with ICC profiles. I dont have a LAB ICC profile, only an old Kodak CM 'precision transform' file which does not show up. So they are not directly going after the Lino method of using LCH editing.
The proprietary issue for me is the default CMYK table - which is fantastic for most work. This gives much better colour than the ICC options - but not detail in some cases.
It is my guess that this is a gamut compression issue - or lack of it. The default tables we like would use relcol rendering, so this probably accounts for the lack of detail in some tough originals.
We rarely (never) scan in ICC mode, or as RGB and convert in Photoshop - which does have certain benefits for certain images.
The 'Device Link Profiles' in question are proprietary - but only in the sense that they are a scanner preset.
You can choose default tables or ICC methods describing your RGB or CMYK scans - the device link profile is just a package for holding these proprietary or ICC settings along with scanner functions such as endpoints, gradation, USM etc.
The problem is that some of this is ICC, some is scanner specific - all bundled up in a proprietary file. The confusion in my mind is the word 'profile' - not all profiles are ICC profiles. CreoScitex use the term, which creates confusion since the only other option for defining RGB or CMYK is through ICC profiles, with or wthout the use of these specific scanner settings.
One thing that I find amusing is how beauty is in the eye of the beholder. I have read comments from noted ICC proponents on other lists that they would not use the CreoScitex gear because of how poorly it handles CM (or used to).
My problems are more petty.
If you do a full bed preview of many originals - before making your various crops/scans you can only set the crops at this postage size preview.
After you do an aptly named 'crop preview' - there is no way to fine tune the crop, which must be done in Photoshop.
This way you are forced to overshoot, so that critical edge content is not missed. But this is a workflow issue, the scanner is designed for premounting of originals on registration pin punched sheets - and the scanner automatically scans and crops out the pre configured mask window positions.
If you do not have the image rotated correctly - there is no way to do this in scanner software, only mirroring. You have to rotate the image in Photoshop.
The prosumer Umax MagicScan software that I used to use did all this and more. At least software can be upgraded, if CreoScitex ever get a clue.
And one final observation which really amuses me - and is probably why some pundits hate the scanner/software:
There is no histogram display (sorry to mention the H word Dan) [g]
I find the Leaf approach of mapping a simple three point curve over a histogram interesting...it would make some levels users more comfortable using curves.
The EverSmart softwares curve control has a nice feature which is on my wish list for Photoshop - a diagonal reference line is always dispayed.
This lets you quickly visually judge exactly how steep the curve is in relation to neutral, as well as bringing the curve back to true in the midtones and shadows, while you tweak the quartertones (for example). Such a simple visual aid is very, very nice - and seems obvious for Photoshop in hindsight.
Sincerely,
Stephen Marsh.
From: INTERNET:amerphoto@ix.netcom.com, INTERNET:amerphoto@ix.netcom.com
Date: Tue, Oct 9, 2001, 2:13 PM
RE: [colortheory] Why is this?
Why is this?
I'm just expermenting.
I take an old Tin Type photo.
I then adjusted in Lab for contrast.
I then change to CMYK and
I deleted the Black channel
(since I see a lot of scratches and spots in Black channel)
...and all of a sudden 90 percent of scratches and spots are gone.
It even looks sharper than the original without sharping it.
Also, I see more detail.So, why is that?
Why are the scratches and spots gone?
Why is it more sharper and has more detail.
What is it about removing the black channel that
causes this?I then go to Greyscale mode and back to LAB and CMYK curves
to bring back the contrast and blacks.I just want to know, what is the Black channel all about?
Am I doing something right or wrong?
Thanks,
Hector Davila
From: Chris Brown, INTERNET:cb@chrisbrownphoto.com
Date: Tue, Oct 9, 2001, 5:04 PM
RE: Re: [colortheory] Scanning Class information??
Re. Scanning Class:
> I have been seeking out a scanner operator class with no luck (all
> that I found are on-site and product-specific classes). I did find one in
> the UK but being on the west coast, that's a little further than I care to
> travel. I have not seen any such course offered by Sterling-Ledet but am
> assuming such information is available to them. I'm hoping for a more
> general (if possible) class, and since I am not currently working,
> "on-site" is not an option. Hopefully with a class of this type added to my
> resume the dry market might dampen up.
>
> Anyway, noticing a new thread in the discussion group as well as your
> standing in the education field, I thought I might inquire as to your
> knowledge of the availability of any such courses. Any information and/or
> recommendations of such courses would be appreciated.Try posting your questions and queries on ScanHi-End@yahoogroups.com
Although the discussions can get equipment-specific, I have found answers to most of my film scanning questions, from oil mountnig film on a drum to mapping RGB values to a specific output targets. There are even several software and hardware representatives who read and post on a regular basis.
As for the whole UCR, GCR, UCA discussion, it really helps to talk to actual press operators. The bigger the press and volume of the printing company, the better. These people really know why an image might print poorly or perfectly, if it has too much overall ink, or the sep is (color) biased in some way, etc.
Chris
@
Chris Brown Photography
http://www.chrisbrownphoto.com
Vox: (217) 356-0540 * Fax: (217) 356-1394
From: INTERNET:samarsh@ozemail.com.au, INTERNET:samarsh@ozemail.com.au
Date: Tue, Oct 9, 2001, 8:01 PM
RE: [colortheory] Re: Why is this (noisy k plate)?