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 CMYK to CMYK Transformation in Photoshop

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Sandman

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PostSubject: CMYK to CMYK Transformation in Photoshop   Mon Sep 29, 2008 10:23 pm

CIECAM wrote:
Probably, some graphic artist does not know what is tagging or embedding or converting colors. And it boils down to color management system.

You're absolutely right, CIECAM. But even if the designers or prepress specialists know how to tag, embed or convert colors, if they're using Photoshop to do this then the results may still be problematic especially with the transformation of:

a] CMYK tints & screens;
b] Black only texts; and
c] Grayscale photos;

That's why you're right by saying that some sort of a color management system (CMS) is needed.

Photoshop's way of a CMYK to CMYK transformation will convert black only elements into 4 colors.

Because from the original CMYK (US Web Coated) Photoshop will convert this to its internal profile connection space (CIELab or X,Y,Z) then onto the destination CMYK (ISO coated). Thus, the results are at times unacceptable.

That's why we need to have a 3rd party.....a CMS. Because many CMS have a device link function.

With this the source color is transformed to the destination color via Device Link, and not using a profile connection space. Ergo, the values of CMYK photos, vectors are transformed but the black texts, screens, tints....will remain black only.

So many high-end color servers are there but it also has an incredible price tag (eg. ALWAN CMYK Optimizer, OneVision's ASURA, etc.)

But cheaper ones like Acrobat plugins I mentioned in another thread can also be used with acceptable results (pdftoolbox4, Apago PDF Enhancer, Heidelberg Color Editor, etc.).


Last edited by larrysison on Tue Sep 30, 2008 5:40 pm; edited 1 time in total
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Indigz

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PostSubject: Re: CMYK to CMYK Transformation in Photoshop   Tue Sep 30, 2008 3:27 pm

thanks, for this thread. just on time thinks this is the reason why I have such trouble in color matching, now I know. Btw, I am a press operator (digital), used to be a spectator of this forum, I just cant find anything to share I am still new with the industry and still learning.
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Sandman

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PostSubject: Re: CMYK to CMYK Transformation in Photoshop   Tue Sep 30, 2008 5:38 pm

Hi Indigz. Glad to have you on board. Are you in Canada? Please feel free to post your questions especially on color management. Or you could also PM Billy, or icc_user for further inquiry on digital presses.
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Indigz

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PostSubject: Re: CMYK to CMYK Transformation in Photoshop   Wed Oct 01, 2008 10:40 am

yap, that would be great!!!
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Alex Dulay



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PostSubject: Re: CMYK to CMYK Transformation in Photoshop   Thu Jan 08, 2009 12:45 pm

Buhayin ko lang itong thread na ito, para may pag-usapan.

CMYK to CMYK conversion in Photoshop will work fine. A simple logic of where do graphic artists create their bitmap photos will point out that the CMYK to CMYK conversion in Photoshop will give you no problem. Use "convert to profile" command in Photoshop.

If the file is a PDF, common sense will tell us not to open the file in Photoshop. Open it in Acrobat, then open the photos in Photoshop and convert it to desired icc profile or even custom GCR separation.

Sorry guys, I just wanted to point out that small printers who can not afford CMS could still do things that can yield very good result. CMS with Device Link is very expensive. I think the real benefits of CMS with Device Link is its ability to use maximum black GCR to save inks and yes it's very fast.

And I strongly recommend for small printers to upgrade to Acrobat 9 Pro if your workflow includes PDF.
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Sandman

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PostSubject: Re: CMYK to CMYK Transformation in Photoshop   Thu Jan 08, 2009 4:36 pm

Alex Dulay wrote:
CMYK to CMYK conversion in Photoshop will work fine. A simple logic of where do graphic artists create their bitmap photos will point out that the CMYK to CMYK conversion in Photoshop will give you no problem. Use "convert to profile" command in Photoshop.

Regular photos...then I agree there won't be any problem. But what about customer supplied advertisements? Some clients provide ads in eps or tiff. The problems begin when the file has "black only" elements (texts, logos, screens) or if the design itself is mixed CMYK with some "grayscale only".

Converting this file in PhotoShop, Acrobat Pro or Enfocus...despite having the correct source and destination profiles, despite having the much needed rendering intent has its limitation. It will contaminate these elements into having other colors that your customer may...or may not like.


Alex Dulay wrote:
If the file is a PDF, common sense will tell us not to open the files in Photoshop. Open it in Acrobat, then open the photos in Photoshop and convert it to desired icc profile or even custom GCR separation.

This is one good solution that I've been using for several years. But since Acrobat Pro 8 & 9 we don't need to open the photos in Photoshop. We can go to Touchup Object then left click on the image, then right click and select Properties, finally we select the Color Tab where we can set our destination profile and rendering intent to be used. This is a very powerful feature from the new Acrobat Pro as you can choose your rendering intent.

Alex Dulay wrote:
Sorry guys, I just wanted to point out that small printers who can not afford CMS could still do things that can yield very good result. CMS with Device Link is very expensive. I think the real benefits of CMS with Device Link is its ability to use maximum black GCR to save inks and yes it's very fast.

I agree that they can achieve good results but to a certain extent. I just want to add. The ability to use Maximum GCR to save ink is not exclusive to programs with Device Link only. We can do this also in PhotoShop, Acrobat Pro and Enfocus. But once again, beware of the unwanted contamination on your solids and black only elements.

With the Device Link your elements are converted to the new destination colors space and yet your solid colors will remain pure...plus...black elements are preserved in the K channel only.

Admittedly, programs with Device Link feature are quite pricey. Pero depende din yan kung ano ba talaga ang gusto mo as a printer. Para sa akin a printer does not need the latest Adobe CS products (InDesign, Illustrator, Photoshop, Acrobat) pero it is a must to get something that can do Preflight Checking, Auto Correction, and Device Link conversion all in one go.


Last edited by larrysison on Thu Jan 08, 2009 9:47 pm; edited 1 time in total
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Alex Dulay



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PostSubject: Re: CMYK to CMYK Transformation in Photoshop   Thu Jan 08, 2009 6:41 pm

For the sake of argument, hehehe.

I think I'm just brave enough to do things in my way as tools are not available. Maybe lucky enough to have good results and clients do not complain.

EPS or TIFF, I used the combination of Illy, PS and Acrobat to fix it.

FWIW, how do you think CMS convert CMYK to CMYK without affecting the the black channel? My wild guess is only the dot gain is being changed to fit with corresponding paper stock and ink. So, figure how I do it in PS (hehehe, I know you knew).

Tools are really a must. But for printer with limited resources, there are work around.
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Alex Dulay



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PostSubject: Re: CMYK to CMYK Transformation in Photoshop   Thu Jan 08, 2009 6:59 pm

Oh and before PDF, EPS and TIFF are the standards.
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Sandman

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PostSubject: Re: CMYK to CMYK Transformation in Photoshop   Thu Jan 08, 2009 8:20 pm

Alex Dulay wrote:
For the sake of argument, hehehe.

This is what I really miss Alex when we used to work together. We used to argue with several technical issues and because of this I have learned many things from you.

Alex Dulay wrote:
I think I'm just brave enough to do things in my way as tools are not available. Maybe lucky enough to have good results and clients do not complain.

That's what everybody else does. The idea behind our posts is to serve as a guide when they start to convert things manually so as to know the pitfalls and the dangers behind it. You are a highly technical guy but most of our colleagues, especially print owners, are not aware of such dangers.


Alex Dulay wrote:
FWIW, how do you think CMS convert CMYK to CMYK without affecting the the black channel? My wild guess is only the dot gain is being changed to fit with corresponding paper stock and ink. So, figure how I do it in PS (hehehe, I know you knew).

And I'm certain you're trying to pretend you do not know this. hehehe.

Actually, hindi lang dotgain ang binabago. Pati na rin ang ink limit nababago din. Madaming paraan to do this without Device Link....pero matagal nga lang.

Pwede naman na tayo lang ang mag-create ng Custom CMYK profiles sa PhotoShop with a Maximum GCR. We can then apply this Max GCR SELECTIVELY sa mga elements na naging 4-colors to force all the unwanted colors in the CMY to go to the K channel only.

I fully agree with you that print providers should know the different workarounds for different situations.

So, do I get to meet you here in 2 or 3 months? Mag empake ka na kaya. hehehe cheers
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