Untitled Document

Dan Margulis Applied Color Theory

Checking for Ink Density

Posted by: "mfedecky"

Mon Jul 16, 2007 2:18 pm (PST)

Is there any efficient way to check the ink densities (Total Ink Limit) of large quantities of images. I've tried Flightcheck Pro (Demo) but it just does not yield accurate results. The only other way I can see is too open each image file and poke around with the ink dropper while keeping an eye on the Info Palette. Hardly something I want to do. Any suggestions?

Michael Fedecky

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Re: Checking for Ink Density

Posted by: "Mike Russell"

Mon Jul 16, 2007 3:47 pm (PST)

This might help. Each of the actions in this set will select areas above a specified TIL. You would still need to open each image and manually see which ones generate a selection. There may be a way to adapt it for your purposes. For example, you run this as part of a batch action that saved each selection as an image, then look at the thumbnails for significant selected areas

http://curvemeister.com/downloads/cmyk_tac/index.htm

Mike Russell - www.curvemeister.com

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Re: Checking for Ink Density

Posted by: Stephen Marsh

Tue Jul 17, 2007 2:11 am (PST)

Thanks Mike, I am glad that you made this action set and have brought it to the lists attention again, thank you for your generosity in making this freely available to the image editing community.

I like the idea that you mentioned of using the action for use in a custom batch action, to create say a blank grayscale file filled with black where the excess ink is, then using Bridge or whatever to visually evaluate the image thumbnails for large areas of black.

This appears to be another area of prepress where development is slow/forgotten. I know Acrobat 7 Pro can check for ink density as part of the preflight process, but it is not that productive (unless scriptable?), and of course the file needs to be PDF. So no help.

A quick Google search kicked up this feature in Intellihance:

http://www.ononesoftware.com/detail.php?prodLine_id=3

"Paper & Ink prevents overinked/underinked areas when printing. Applies to CMYK and Grayscale printing, not RGB. Intelligently adjusts Dot Gain and Limits and changes Total Ink Limit on CMYK or Grayscale images to reflect printing industry standards for the following types of paper: Coated Commercial 150 LPI; Uncoated Commercial 133 LPI; Coated SWOP 133 LPI; Uncoated SWOP 120 LPI; Uncoated SWOP Newspaper; Proof."

This prepress feature surprises me, in a pleasant way, even more so considering the nature of the product (I have not followed it since it's early days, when it did not impress me).

The old Macromedia xRes image editing app had a filter to perform reworking of existing CMYK values into different GCR/UCR and ink limit settings, perhaps LivePicture and other old apps did too. Unless there was some sort of evaluation being performed, one would have to run every image through such a filter, rather than only the ones that were over the limit. So far from ideal.

Mike's actions seem the best bet for now, unless somebody else has a suggestion and would like to delurk?

Regards,

Stephen Marsh.

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Re: Checking for Ink Density

Posted by: "Jono Moore"

Wed Jul 18, 2007 1:39 am (PST)

On 7/16/07, Stephen Marsh wrote:

This appears to be another area of prepress where development is

slow/forgotten. I know Acrobat 7 Pro can check for ink density as part

of the preflight process, but it is not that productive (unless

scriptable?), and of course the file needs to be PDF. So no help.

Good idea, and should be easy enough to do (I don't think you'd need scripting).

You can point Acrobat at a directory full of images and convert them to pdf - make sure to turn off any colour conversion first - then run the preflight.

Jono Moore

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Re: Checking for Ink Density

Posted by: "mfedecky"

Wed Jul 18, 2007 4:52 am (PST)

I believe using the Preflight feature in Acrobat 7 only works on "objects" and not on images unless I'm missing something.

Thanks

Michael Fedecky

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Re: Checking for Ink Density

Posted by: Stephen Marsh

Wed Jul 18, 2007 5:02 am (PST)

Thanks Jono, I am happy to be informed of capabilities that I have not yet discovered! I will try to look into this tomorrow, I usually perform manual preflighting and don't know about the ink police feature in detail and was not sure if it worked in batch mode or whatever.

Regards,

Stephen Marsh.

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Re: Checking for Ink Density

Posted by: Stephen Marsh

Wed Jul 18, 2007 5:03 am (PST)

I don't know Michael, I manually preflight via the built in print preview palette (the eye on the page icon, I am not in front of the app as I write this) can show various separations, smooth shades, vector elements, raster elements etc in isolation, alowing one to view the various colour and object builds. The densitometer in this palette correctly reports TIL for both raster and vector. This is not the same thing as using the automated preflighting though - so what you mention may indeed be the case and you are perhaps missing nothing, I don't know! I will try to confirm this tomorrow. Thanks for the post, I use Acrobat Pro every day but only a small part of it's feature set.

Sincerely,

Stephen Marsh.

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Re: Checking for Ink Density

Posted by: "Jono Moore"

Wed Jul 18, 2007 6:43 pm (PST)

Ok, so unfortunately the built-in preflight in Acrobat (I'm playing with v8 Pro) doesn't check TIL in images - only vector objects.

But the output preview does. So, you could still do a mass convert to pdf and then turn on the output preview with your ink limit set and page through the pictures quickly to see if anything shows up.

You can also do this in InDesign using Output->Separations Preview and selecting Ink Limit from the drop box instead of Separations.

Pitstop Pro for Acrobat will check for TIL in images, but I haven't played with it.

Jono Moore

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Re: Checking for Ink Density

Posted by: "mfedecky"

Thu Jul 19, 2007 4:52 am (PST)

"Jono Moore" wrote:

Ok, so unfortunately the built-in preflight in Acrobat (I'm playing

with v8 Pro) doesn't check TIL in images - only vector objects.

But the output preview does. So, you could still do a mass convert to

pdf and then turn on the output preview with your ink limit set and

page through the pictures quickly to see if anything shows up.

Jono, this is great information, thanks.

I can't seem to get the black plate to show up in the Acrobat "Output Preview" so I'm only getting the Ink Density for 3 separations.

You can also do this in InDesign using Output->Separations Preview and

selecting Ink Limit from the drop box instead of Separations.

This must be a InDesign 3 feature because it doesn't show up in InDesign 3.

Thanks

Michael Fedecky

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Re: Checking for Ink Density

Posted by: "RJay Hansen"

Thu Jul 19, 2007 10:33 am (PST)

Actually up to version 6.53, Pitstop Pro only checks TIL in vector objects. We aren't using the current version--7 though. They may have added this feature.

RJay

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Re: Checking for Ink Density

Posted by: "Jono Moore"

Fri Jul 20, 2007 2:19 pm (PST)

Yes, it's in version 7.

Jono Moore

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Re: Checking for Ink Density

Posted by: "Jono Moore"

Fri Jul 20, 2007 3:19 pm (PST)

On 7/19/07, mfedecky wrote:

I can't seem to get the black plate to show up in the Acrobat "Output Preview" so I'm only

getting the Ink Density for 3 separations.

Not sure what the problem would be there. But I think there are options for which plates to view. I'll have to check Acrobat 7 at work on Monday. I only have CS3 installed at home at the moment...unless I get bored this weekend maybe I'll put CS2 in a virtual machine.

This must be a InDesign 3 feature because it doesn't show up in InDesign 3.

I'm pretty sure I was in CS2 when doing it. I remember using it before having CS3, as well. I've got both installed at work so I can check it out on Monday.

Jono Moore

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Re: Checking for Ink Density

Posted by: "Stephen Ramirez"

Sat Jul 21, 2007 6:29 am (PST)

I do not have InDesign CS3 yet but can confirm that for InDesign CS2 using Output>Separations Preview and selecting Ink Limit will allow you to check ink limits.

Stephen Ramirez

Re: Checking for Ink Density

Posted by: "garro_carlos"

Sun Jul 22, 2007 8:12 pm (PST)

I do not have InDesign CS3 yet but can confirm that for InDesign CS2

using Output->Separations Preview and selecting Ink Limit will allow

you to check ink limits.

Since the version CS1 InDesign have this feature... In the separation window you can check "total ink limit" in vector an bitmap objects but the

process is manual.

Greetings

Carlos Garro

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Re: Checking for Ink Density

Posted by: "Bevi Chagnon"

Mon Jul 23, 2007 1:51 am (PST)

Yes, InDesign CS3 lets you check ink limits, as well as separations (including exact builds of bitmaps, vectors, text and other live objects in InDesign). It also has a transparency flattener to view what happens to all those drop shadows and new effects in Indy CS3, like bevels.

The panels are under Window > Output.

--Bevi Chagnon

........................................................................

Bevi Chagnon | Adobe ACE: InDesign CS2 | www.PubCom.com

PubCom | Trainers, Consultants, Designers for Web, Print & Acrobat

Bevi's online tutorials | http: //www.CommunityMX.com/author.cfm?cid=5931

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Ink Densities (again)

Posted by: Ric Cohn

Thu Jul 26, 2007 7:19 am (PST)

On Jul 20, 2007, at 8:26 PM, Stephen Ramirez wrote:

I do not have InDesign CS3 yet but can confirm that for InDesign CS2

using Output->Separations Preview and selecting Ink Limit will allow

you to check ink limits.

I was going to mention the Output>Ink Limits preview in InDesign, but was beat to it. This function was pointed out to me by a pre-press person recently for checking some files I had worked on. However, I notice that InDesign appears pretty liberal in what it highlights as over ink limit and it got me thinking about where I might need more knowledge. I recently prepared a number of images for reproduction with a 300 TIL. I tried to stay within the 300 total as I worked. When I checked the images in an InDesign document some largish areas of deep shadow highlighted as "over". For example, the darker parts of a person with black hair. When I reopened these files I found that either they were up to but not over the 300 total ink limit or there were very small areas that were over by a few points. Sometimes it only showed as over 300 Total Ink if I had my eyedropper set to "point" sample. Here are some questions.

1. For anyone using the Ink Limits preview in InDesign (or any other program), do you make sure there are no highlighted problem areas, or do you ignore small areas?

2. I had always heard that small areas a little over ink limit (no bigger than a dime sticks in my mind) would not cause a problem or cause a job to be rejected by a printer. Is this correct? How much over, if anything, is OK?

3. What eyedropper sample size should be used to measure the Total Ink? I would think 3x3 would make sense, but it appears that InDesign is more rigid in what it shows as Over Limit.

4. As long as the total ink is under the max is there a problem raising the Black up to or near 100%?

5. In my files, a lot of the tiny over 300 Total Ink areas happened with the final sharpening. Do people take these into consideration when looking for Over Limit areas at the end? Do they bring the TIL back down after sharpening?

6. As far as reducing an Over Limit area, I assume there is not one best way? But what do people do? Selective Color set to Blacks and reducing the CMY seems reasonable, although on screen it sometimes appears that using Layer Blending to restrict the drop to the darkest blacks looks better. What about using the bottom controls in Levels to reduce the darkest black? Or do you really need to do small adjustments on individual channels with Curves?

7. Assuming I'm correct that small areas Over Limit are OK, how much over and how big?

Any answers to these questions will be greatly appreciated.

Ric Cohn

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Re: Ink Densities (again)

Posted by: "RJay Hansen"

Thu Jul 26, 2007 9:14 am (PST)

A few answers from the perspective of our printshop.

On 7/26/07, Ric Cohn wrote:

2. I had always heard that small areas a little over ink limit (no

bigger than a dime sticks in my mind) would not cause a problem or

cause a job to be rejected by a printer. Is this correct? How much

over, if anything, is OK?

There's probably no hard, fast answer to that question. It will vary with the nature of the job and the stock being printed on, but yes, small, insignificant areas can generally be ignored although some printers may be more strict about that.

Just as much as the size of the area(s) over the limit, we consider how *much* over the limit an image may be. On our newsprint stocks, our limit is 250%. I'm a lot more worried about finding 300% coverage in an image than finding 258% coverage.

3. What eyedropper sample size should be used to measure the Total

Ink? I would think 3x3 would make sense, but it appears that InDesign

is more rigid in what it shows as Over Limit.

To an extent, this would depend on an image's resolution, however, no matter what the resolution, 1 pixel samples seems to be ridiculously strict. For an image printing at 200ppi or greater, 5x5 would probably be sufficient although I generally have my eyedropper set to 3x3.

4. As long as the total ink is under the max is there a problem

raising the Black up to or near 100%?

Once again, there could be a lot of variables affecting this, but we generally don't have problems with this. That being said, the Custom CMYK we request our customers to implement has an 85% limit for black on our web presses and 90% limit for sheetfed jobs.

5. In my files, a lot of the tiny over 300 Total Ink areas happened

with the final sharpening. Do people take these into consideration

when looking for Over Limit areas at the end? Do they bring the TIL

back down after sharpening?

I'm not directly answering this question, but it makes me wonder a bit. I find most images tend to come in with a TIL around 8 - 15% (roughly) less than the TIL we have set in Custom CMYK when separated in Photoshop. Because of this I can usually do some contrast enhancing, which will usually entail pulling the shadow end down some in all colors (increasing the ink) as well as giving the black an extra boost in the shadows if needed and still rarely go over the ink limit.

That implies that if you are seeing the total coverage go over the limit after sharpening, you are a lot closer to it to begin with than what I'm usually seeing.

7. Assuming I'm correct that small areas Over Limit are OK, how much

over and how big?

See answer to question 2.

HTH. I imagine you'll get some other answers to this too. As I indicated, this will vary with different printers as well as the nature of the job in question.

RJay

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Re: Ink Densities (again)

Posted by: Ric Cohn

Fri Jul 27, 2007 11:57 am (PST)

RJay, Thanks for your response. It was very enlightening. I hope more printers and other experts on this list will share their viewpoints. I also hope this is of interest to others on this list.

On Jul 26, 2007, at 11:33 AM, RJay Hansen wrote:

I'm not directly answering this question, but it makes me wonder a

bit. I find most images tend to come in with a TIL around 8 - 15%

(roughly) less than the TIL we have set in Custom CMYK when separated

in Photoshop. Because of this I can usually do some contrast

enhancing, which will usually entail pulling the shadow end down some

in all colors (increasing the ink) as well as giving the black an

extra boost in the shadows if needed and still rarely go over the ink

limit.

That implies that if you are seeing the total coverage go over the

limit after sharpening, you are a lot closer to it to begin with than

what I'm usually seeing.

Yes, I have done the kind of adjustments to these files that I hope someone like you would agree with.

Any over limit areas are small and only in areas that should print black. The files are meant to be press ready for the conditions they have been prepared for using a custom profile supplied by my client.

I would have thought they were OK if not for the highlighted over ink limit areas shown by InDesign. Now I'm wondering if I should be more conservative or if most people ignore the warnings in deepest blacks as long as the areas aren't large or are only a few percent over?

Ric Cohn

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Re: Ink Densities (again)

Posted by: "RJay Hansen"

Fri Jul 27, 2007 12:52 pm (PST)

Ric,

My main caveat to having the TIL too high in small insignificant areas is that there are some print shops that will run a prefllight and if a file fails *any* of the preflight's parameters by *any* amount, they will immediatly reject it, when further inspection may show the way in which it failed was insignificant to successful output and printing.

Automated preflighting is great for the printing industry, but like color management, there are times when a human can and should make a judgement that a machine is incapable of.

I was interested in seeing more responses to your questions too and am a bit surprised there haven't been any. :-/

rjay

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Re: Ink Densities (again)

Posted by: J Walton

Sat Jul 28, 2007 6:56 am (PST)

On 7/26/07, Ric Cohn wrote:

1. For anyone using the Ink Limits preview in InDesign (or any other

program), do you make sure there are no highlighted problem areas, or

do you ignore small areas?

I ignore small areas if they aren't too far over. However if you know the printer or publication has dummies working the preflight desk even 5% over dmax in a pixel or two will get rejected, so you are better off fixing it.

For the last few years I've done precious little tweaking in CMYK after conversion so DMAX issues really haven't come up.

2. I had always heard that small areas a little over ink limit (no

bigger than a dime sticks in my mind) would not cause a problem or

cause a job to be rejected by a printer. Is this correct? How much

over, if anything, is OK?

I recall that it was no more than a nickel, but after reading the SWOP guidelines a few years ago I've changed that to 1/4 inch square. Remember that an area that's a little bit high the size of a quarter is nothing compared to an area way too high the size of dime.

3. What eyedropper sample size should be used to measure the Total

Ink? I would think 3x3 would make sense, but it appears that InDesign

is more rigid in what it shows as Over Limit.

3x3 is good.

4. As long as the total ink is under the max is there a problem

raising the Black up to or near 100%?

Not necessarily - but you need to make sure that won't cause problems with your specific print conditions.

5. In my files, a lot of the tiny over 300 Total Ink areas happened

with the final sharpening. Do people take these into consideration

when looking for Over Limit areas at the end? Do they bring the TIL

back down after sharpening?

I tend to do sharpening before CMYK conversion, so no.

6. As far as reducing an Over Limit area, I assume there is not one

best way? But what do people do? Selective Color set to Blacks and

reducing the CMY seems reasonable, although on screen it sometimes

appears that using Layer Blending to restrict the drop to the darkest

blacks looks better. What about using the bottom controls in Levels

to reduce the darkest black? Or do you really need to do small

adjustments on individual channels with Curves?

There isn't one best way, but if you had to choose one way I'd say converting back and forth would be the best. Selective Color blacks is quickest, channel mixer works too.

7. Assuming I'm correct that small areas Over Limit are OK, how much

over and how big?

It depends on whether or not you're trying to outsmart a preflight dummy or if you are just concerned about how it prints.

I'd say you're pretty safe if your TIL is less than 10% over. If a few small areas (1/4 inch) are 15% or even 20% you might be OK, but at that point a simple convert-convert-layer mask out-brush back in is fast enough that you may as well fix it.

J Walton

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Re: Ink Densities (again)

Posted by: Ric Cohn

Sat Jul 28, 2007 10:23 am (PST)

If I understand correctly: Make a copy, convert to RGB and back to CMYK, place this as a layer over the original with a black layer mask and paint in the offending areas.

This seems like an excellent way to fix specific areas without affecting anything else.

Thanks,

Ric Cohn