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Color Profiles

Posted: Mon Feb 03, 2020 2:59 pm
by RytisT
Hi. I'm not that familiar with color profiles as I'd like to admit.

I want to convert any incoming color profile/color space in PDF to FOGRA39, without loosing CMYK values.
Is it possible? As I understand the only way is with DeviceLink? But there is no DeviceLink that would fit me, what can I do here? Any way to make DeviceLinks or do it without DeviceLinks? Thank you.

Re: Color Profiles

Posted: Fri Feb 07, 2020 10:54 am
by bens
If I understand correctly you want the tagging actions. When tagging an object with an ICC profile, PitStop will not change the CMYK values. You can do this in the Inspector with the ICC dropdown, or in an Action List with "Tag object with an ICC profile". As long as you only use the "tag" (and perhaps "untag") actions, the exact values won't change. Just stay away from any action that has "convert" in its name, because those will do actual colour managed conversions and hence change the CMYK values.

Re: Color Profiles

Posted: Sun Feb 09, 2020 8:14 pm
by abailescollins
If I understand your question correctly.
You want to convert the file to CMYK using a Fogra 39 profile, but not touch an EXISTING CMYK?

If that's correct then a conventional ICC color conversion will do that.
It will convert everything else (or whatever colorspaces you define) to CMYK, but not touch existing CMYK.

The only exception would be any CMYK that is tagged with an ICC profile. And the only exception to that is any CMYK that is tagged with the (exactly the same) ICC profile you are using to do the ICC conversion. They won't be touched.

A Devicelink profile is does a pure CMYK to CMYK conversion, but does not go through Lab, so C, M, Y, K and CM, CY, MY can be preserved.
In PitStop you can only do a Devicelink conversion on a DeviceCMYK color. So a CMYK that DOES NOT, have an ICC profile attached.

Re: Color Profiles

Posted: Mon Feb 10, 2020 7:18 am
by RytisT
All I want to do is make sure every file I let through pitstop server, ends up being FOGRA39 color profile, but clients sometimes send files with ISO Coated or Web Coated swop, and so on... so, I don't suppose DeviceLink will work if I'll have a different color space every time?

Re: Color Profiles

Posted: Mon Feb 10, 2020 10:23 am
by bens
RytisT wrote:
Mon Feb 10, 2020 7:18 am
All I want to do is make sure every file I let through pitstop server, ends up being FOGRA39 color profile, but clients sometimes send files with ISO Coated or Web Coated swop, and so on...
That does indeed sound like a normal colour conversion to FOGRA39, as Andrew said. For this you'll need to set the output CMYK profile to FOGRA39 (note this can be done globally or inside an Action List with "override color management") and do:

Convert color to CMYK
Tag object with FOGRA39

Note that this will change the actual CMYK values - the intent here is to keep the colour appearance, not the device values.

The tricky part is, potentially, getting the correct input profile. If objects in the input file are tagged correctly there is no problem. But if they're not tagged or otherwise indicate which device settings they use you'll need to get that information from somewhere else and set the correct profile in the "Source" part of your colour management settings.
RytisT wrote:
Mon Feb 10, 2020 7:18 am
I don't suppose DeviceLink will work if I'll have a different color space every time?
Correct - but as I tried to explain above you don't need one. A DeviceLink is just a shortcut between two normal profiles, so if you know the source and target you can just convert normally.

Re: Color Profiles

Posted: Tue Feb 11, 2020 11:27 pm
by abailescollins
RytisT wrote:
Mon Feb 10, 2020 7:18 am
but clients sometimes send files with ISO Coated or Web Coated swop, and so on... so, I don't suppose DeviceLink will work if I'll have a different color space every time?
Ok so let's examine this in more detail. Imagine a customer sends in a PDF that has a Output Intent or an image that is tagged with a JapanColor2011Coated ICC profile. Looking at the ICC web site (http://www.color.org/registry/index.xalter) that profile has a Maximum Ink Coverage of 350% and a K separation maximum of 80% and a TVI (Dot gain) of 14%

Now the really interesting thing (stay with me), is that Fogra 39 is not an ICC Profile. It's a data set, from which you can make an ICC Profile. ISO Coated v2 is a prime example (there are others). So there are actually many profiles that can be Fogra 39!

Take one as an example. The documentation for the ISO Coated v2 ECI profile says
The ECI offset profile ISOcoated_v2_eci.icc is based on the characterization dataset “FOGRA39L.txt” applicable to for the following
reference printing conditions according to the international standard ISO 12647-2:2004/ Amd 1:
The profile was generated using Heidelberg PrintOpen 5.2 with the following settings:
Black length 9 (starting point 10%)
Black width 10
Total dot area 330%
Maximum Black 95%

So this profile will color separate an image in a completely different way to the Japanese profile. Different Ink Coverage (330% instead of 350%), and different Max Black (95% vs 80%). The dot gain will also be different. So the actual color separations created by the profiles will be different.

So ideally after conversion, what you want is for the color separation attributes to match that of your target profile, but the image to still maintain the same visual appearance it had when you received it. That is what a Devicelink can give you.
The issue as you say is that you would need a Devicelink for every possible combination of potential source ICC profile to your target ICC profile.
There are tools that will do this. Alwan Color, GMG and Colorlogic can do this. They either build and cache Devicelinks on the fly when they get a profile combination they haven't seen before. Or they just have a hell of a lot of profiles.

It really depends how far you want to go with this.
If you do decide to go down this path you can then look at using Devicelinks for Ink Saving, which is another use for them.
Not just lowering tac, but replacing CMY with K based on Gray Balance to reduce the amount of colored ink needed to print the job.

Re: Color Profiles

Posted: Wed Feb 12, 2020 1:31 pm
by RytisT
abailescollins wrote:
Tue Feb 11, 2020 11:27 pm
RytisT wrote:
Mon Feb 10, 2020 7:18 am
but clients sometimes send files with ISO Coated or Web Coated swop, and so on... so, I don't suppose DeviceLink will work if I'll have a different color space every time?
Ok so let's examine this in more detail. Imagine a customer sends in a PDF that has a Output Intent or an image that is tagged with a JapanColor2011Coated ICC profile. Looking at the ICC web site (http://www.color.org/registry/index.xalter) that profile has a Maximum Ink Coverage of 350% and a K separation maximum of 80% and a TVI (Dot gain) of 14%

Now the really interesting thing (stay with me), is that Fogra 39 is not an ICC Profile. It's a data set, from which you can make an ICC Profile. ISO Coated v2 is a prime example (there are others). So there are actually many profiles that can be Fogra 39!

Take one as an example. The documentation for the ISO Coated v2 ECI profile says
The ECI offset profile ISOcoated_v2_eci.icc is based on the characterization dataset “FOGRA39L.txt” applicable to for the following
reference printing conditions according to the international standard ISO 12647-2:2004/ Amd 1:
The profile was generated using Heidelberg PrintOpen 5.2 with the following settings:
Black length 9 (starting point 10%)
Black width 10
Total dot area 330%
Maximum Black 95%

So this profile will color separate an image in a completely different way to the Japanese profile. Different Ink Coverage (330% instead of 350%), and different Max Black (95% vs 80%). The dot gain will also be different. So the actual color separations created by the profiles will be different.

So ideally after conversion, what you want is for the color separation attributes to match that of your target profile, but the image to still maintain the same visual appearance it had when you received it. That is what a Devicelink can give you.
The issue as you say is that you would need a Devicelink for every possible combination of potential source ICC profile to your target ICC profile.
There are tools that will do this. Alwan Color, GMG and Colorlogic can do this. They either build and cache Devicelinks on the fly when they get a profile combination they haven't seen before. Or they just have a hell of a lot of profiles.

It really depends how far you want to go with this.
If you do decide to go down this path you can then look at using Devicelinks for Ink Saving, which is another use for them.
Not just lowering tac, but replacing CMY with K based on Gray Balance to reduce the amount of colored ink needed to print the job.
Damn... Thanks a lot for your answer.
I realize that I don't know jack s*** about color profiles, I'll look into the software you suggested.
Thanks again.