GRACoL SWOP and RGB

[lnivin]

Testing a new workflow . . .

If I take the RGB and convert to GRACoL profile.
And again the RGB to SWOP.
And again the SWOP to GRACoL, the final images look different especially in the Cyan separation.

If RGB to GRACoL to SWOP it creates a 3rd different image.

If RGB to SWOP to GRACoL I now have a 4th different image.

Now if I take these Photoshop images into Illustrator, then InDesign, with the Destination Profile as GRACoL they all look a little different in Cyan.

My goal is to get them consistent, which hopefully means exactly the same.

 

[Steelhead121]

You are probably seeing a difference due to how the black separation is being generated. The black generation for Gracol is different than SWOP. When you convert back to RGB, those pixels don't magically go back to where they were. That original RGB image is gone. The color of the new CMYK image will consume different parts of the RGB gamut when converted back to RGB. You are better off keeping your images in RGB and only converting when refining.

 

[lnivin]

It's starting to make sense. After years of telling our customer to supply CMYK images, it seems that now the better workflow is RGB and let Prinergy do the conversion. Even letting InDesign convert to GRACoL seems better with RGB.

 

[Steelhead121]

The beauty of an RGB workflow is that the color gamut of RGB is much greater than CMYK. All the integrity of the RGB image is retained until the final rendering. The end conversion maximizes the ability of the printing method at hand to do reproduce as much of the RGB gamut as is possible within the restrictions of that printing method.

 

[lnivin]

What's the difference between SWOP2013 and GRACoL2013. When exporting PDF from InDesign the SWOP2013 seems to create GRACoL type separations, but the GRACoL2013 seems to not change SWOP files. Even though I've set it to use the Destination Profile which is GRACol2013.

 

[lnivin]

Also during testing I noticed that the Cyan separation looks a little different if first embedded into Illustrator and then into InDesign.

 

[tmiller_iluvprinting]

The SWOP profile is used to describe a profile built from measurement data obtained from web offset printing(Specifications for Web Offset Printing). The GRACoL profile is used to describe a profile built from measurement data obtained from commercial sheetfed printing(General Requirements and Applications for Commercial Offset Lithography). The color gamut of the two descriptions is different because of many factors, the process, the paper, the ink color, etc. Because of this, converting to either of these two standard color spaces will yield different results. Also keep in mind that the rendering intent that you select(the method by which the CMM handles out of gamut colors, and white mapping) will also influence your conversion results. May I suggest that you visit the IDEAlliance website and investigate the online color management course that they offer, well worth the expenditure!

Best,
Todd

 

[lnivin]

Our goal was to have an InDesign PDF that previews like the plates. And I think I finally understand what you've been trying to tell me.

Use the customer embedded profiles to keep their color intentions. If the profile is changed, information can be clipped or changed. Final color separations can be seen under Proof Setup using the GRACoL workspace (which is what we are using) if customer is interested.

The PDF exported from InDesign with the GRACoL Destination Profile attached looks just like the file after it is Refined in Prinergy using the GRACoL settings which is what we were after.

Sound right?

 

[lnivin]

Differences I found when testing workflow. Photoshop files saved as PDF - if Profiles are Not Included the color doesn't change to Destination even if placed into Illustrator or InDesign and a new PDF is created using Include Destination Profile.

Has anyone else seen this? Is this how it's supposed to work?

My concern is images supplied in customer files will not convert to GRACoL (our destination) and print incorrectly.

Note: RGB images seem to not be affected. They convert to final destination no matter how they are saved.

 

[tmiller_iluvprinting]

In Photoshop, if no profile is embedded or included, or even if you choose not to color manage, Photoshop assumes that whatever the color space that is selected in your Color Settings is the profile it should use. Since the profile Photoshop assumed is being used, and the destination profile are the same, Photoshop will do no conversion. If your customer files are supplied with no embedded profile, you would need to assign a profile that you believe your customer used (a leap of faith), or ask your customer what color space they were working in (better than guesswork). Once you have assigned a profile you can now convert to your destination space (as long as the assigned profile and the destination profile are different.) Keep in mind that the Rendering Intent that you select will affect the quality of your conversion. For CMYK-CMYK conversions***** use Relative Colorimetric Rendering. Educate your customers to always embed their profiles. Embedding profiles reduces the chance that your customer's color expectations will not be met (we're not in 1995 anymore!)

******CMYK-CMYK conversions are best handled with a Device Link Profile which does a direct CMYK-CMYK transformation, without using the Lab Profile Connection Space.*******

Regards,
Todd
(T- 13.5 hours and counting!)