Offset & Digital Colorspaces & Conversions

Started by Nate, February 04, 2016, 08:49:17 AM

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Nate

I'm trying to standardize our file preparation, and I'm having a little trouble deciding what colorspace(s) we should target. The more I read about the subject the more I'm realizing how much I still have to learn. :o

OFFSET (Ryobi 525)

First thing I need to figure out is whether we should target GRACoL 2006 or 2013. Reading about GRACoL 2013, it sounds like it's based on reference data from ISO 15339 instead of the 12647 standard I'm used to seeing.

ISO 15339: Printing from digital data across multiple technologies. ISO 12647: Process control for the production of half-tone colour separations, proof and production prints. Are these two distinct standards? Does ISO 15339 encompass the existing ISO 12647?

1) Would there be any real advantage to targeting the new GRACoL 2013?
2) Does ISO 15339 aim to replace ISO 12647?
3) Is GRACoL 2006 still in more common use and therefore would yield a result more consistent with other shops?

DIGITAL (iGen4)

I know the iGen has a wider gamut than the Ryobi, and from the FreeFlow Print Server specs I understand it can emulate GRACoL, SWOP, Euroscale, FOGRA, and Japan Color.
What's the best practice for setting up colors for a digital press with a wide gamut like the iGen?

1) Should we honor the document colorspace and emulate that?
2) Convert to a certain standard before sending to the iGen?
3) Should we be building custom ICC profiles for the iGen on various stocks and convert colors to that colorspace?

I would like for RGB images to be able to utilize the full gamut of the iGen, but it also makes sense that emulating a standard would give more predictable results.

Anything to demystify some of this is much appreciated.

Thanks!

swampymarsh

#1
GRACoL is not my area, however I think that you may have some misinformation. Yes, it is still an offset ISO12647 condition. The major differences between 2006 and 2013 are noted here:

http://www.idealliance.org/downloads/gracol-2013-whats-new-guideline

http://www.idealliance.org/downloads/2013-vs-2006-gracol-swop-profiles

http://fineeyecolor.com/chasing-whitepoint-gracol-2013/

So:

1 - Depends on your success of aligning inkjet proofs to press sheets
2 - Not to my knowledge
3 - I am guessing yes, however it is also related to point 1

As for your digital output...

There are no easy answers! There are a number of technical/production decisions and business decisions for you to make.

1 - Honour RGB input, output conversion from RGB to CMYK is "your choice"
2 - Seems a safe bet, many RIPs are setup to simulate using SWOP unless an informed decision is made to change this
3 - All prints could potentially benefit from custom ICC of the baseline non-colour managed printer output on a specific media, independent on whether you simulate a press condition or not (provided that the output is stable and consistent). Using what you currently have, is it ballpark to your offset print?

I believe that there are more questions than answers!