GRACoL2006_Coated1v2 profile – Need to reduce total ink coverage to 280%

[ClairdJ]

Hello,

I’m using a printer who has requested I use the GRACoL2006_Coated1v2 profile https://www.color.org/registry/GRACoL2006_Coated1v2.xalter but have also requested that I keep the total ink coverage below 280%.

I am using Photoshop. If I batch run the GRACoL2006_Coated1v2 profile on all the images what would be the best way to then reduce the ink coverage without altering the other settings? I have 244 images to adjust.

I can see that I can use a Custom CMYK setting to change the total ink coverage but I’m concerned that this will alter the other settings? In that case should I use curves instead?

Thank you in advance.

[NB, colourmanagement]

@ClairdJ It would perhaps be worth having someone who has the software to do it edit the  GRACoL2006_Coated1v2 profile to lower the TAC (inklimit). Perhaps the printer you plan to use has an edited version, or can provide you with a process they use and trust to achieve what they have requested ?

Its worth mentioning that RGB to CMYK isn't a simple push button process in the case of high gamut images, in case that’s what you are processing. Sometimes pre-comnversion optimisation can be more successful that a straight conversion. e.g. if RGB blues shift  towards magenta in CMYK sometimes happens. 

Viewing the image files on a calibrated screen, post-conversion, is something I'd definitely recommend. 

I hope this helps

neil barstow colourmanagement - adobe forum volunteer,

colourmanagement consultant & co-author of 'getting colour right'

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[ClairdJ]

Thank you. Unfortunatley, the printer hasn't been able to offer an edited version.

[Stephen Marsh]

Thank you. Unfortunatley, the printer hasn't been able to offer an edited version.

By @ClairdJ

That sounds right. They ask you to convert to a profile that nominally delivers 320% (your link) or 340% (Adobe profile) and then ask you to limit this to 280% without providing any practical help! Sadly, this is pretty standard for the industry. As the service provider, they should either provide the correct ink limited profile, provide detailed instructions, or use an internal workflow with a device link profile to convert the standard incoming data to their required 280%,  but that is wishful thinking.

[Stephen Marsh]

@ClairdJ 

Custom CMYK predates ICC profiles and although updated in v5 to create ICC profiles, it isn't based on GRACoL or other modern print specifications and can't be used to directly modify an ICC profile such as one of the GRACoL variants.

There are a few different ways to handle this, I'll post more on this later when I'm in front of a proper keyboard rather than the phone.

[ClairdJ]

Thank you.

[Stephen Marsh · Accepted solution]

You can start here, which should get you to ~298% total ink for a Perceptual rendering and 286% for Relative Colorimetric rendering intent:

https://www.colormanagement.org/en/gracolprofile.html

Then, if really needed, a batch action using selective colour for Blacks, with -3 (negative) relative for each of the C, M, Y without adjusting K would get you there from the 286% start point, if you were going from the 298% then higher values would be needed. A luminosity mask or blend if sliders could also be added to limit this to the darker regions, or to blend in a copy of one profile conversion into the standard profile conversion. There are many options.

[ClairdJ]

Thanks so much for your help. I've used that profile and didn't adjust it any more. It has now gone to print. 🙂

[NB, colourmanagement]

@ClairdJ did you send the files off with a straight CMYK conversion, then? None of Stephen's clever tweaks to cut the max inklimit / TAC?

It would be good to know how it goes in print if you did that. 

In an ideal world the printer would put high inklimit files through color server but it seems this one doesn’t from your original comments.

neil barstow colourmanagement - adobe forum volunteer,

colourmanagement consultant & co-author of 'getting colour right'

See my free articles on colourmanagement online

[Stephen Marsh]

@ClairdJ did you send the files off with a straight CMYK conversion, then? None of Stephen's clever tweaks to cut the max inklimit / TAC?

If @ClairdJ used the Relative Colorimetric conversion in that suggested profile, then the max ink would have been ~286%, which might be accepted by the service provider as being "close enough" to 280%, especially when the common profile conversions would have provided 320-340% total ink. Perhaps the "ink police" will let it slide...

It would be good to know how it goes in print if you did that. 

By @NB, colourmanagement

Agreed, feedback is always good!

[ClairdJ]

@NB, colourmanagement @Stephen Marsh

I did use the Relative Colorimetric conversion and most images didn't go as high as 280%. A few were over 280% but I decided to leave as the printer is running on a different press to before (though requested the same settings.) I've already had the job printed once and the images were too dark.

I’ll let you know how it works when I have the print back. Thanks again for your help.

[Stephen Marsh]

I've already had the job printed once and the images were too dark.

By @ClairdJ

By this do you mean the overall tone was too dark? Or do you mean that you lost shadow detail? Or both?

[ClairdJ]

In general I'd say both.

[Stephen Marsh]

Presuming that you had an inkjet proof correctly simulating the print target, then they aren't printing to GRACoL 2006, the TVI is greater than the specifications. If your observation is only based on your monitor preview, then your expectation could be off, and they might be printing to spec but your monitor preview isn't accurate.

[ClairdJ]

I've now had the print back and it looks much better!

The first time it was printed was on a Canon iX and I made no colour adjustments myself. The second time I used @Stephen Marsh's recommended GRAC profile and it was printed on an Indigo press (which I was told prints lighter).

Thanks again for your help!

[NB, colourmanagement]

@ClairdJ It's good to get confirmation here that Stephen's advice helped you with this. 

Have you marked his reply as correct? That helps others too 

neil barstow colourmanagement - adobe forum volunteer,

colourmanagement consultant & co-author of 'getting colour right'

See my free articles on colourmanagement online