RGB to multiple commercial printers

General Color & Graphics Color Science & ICC Profiles
1

I have a RGB file (in COLORMATCH RGB space).

I send this file to commercial printer A. He converts the RGB file “relative” to his own custom CMYK profile for his press, and provides a hard copy proof.

I then send the same original RGB file(in COLORMATCH) to commercial printer B. He also has a custom CMYK profile for his press and converts “relative” into his press profile and provides a hard copy proof.

Shouldn’t both proofs from 2 different commercial printers look identical?

2

In theory yes but then there could be a difference in gamut, the papers could be different etc.

If you had both profiles and some control over the process, you can apply what is known as cross rendering which attempts to make one device simulate another. This would be a conversion like this:

ColorMatch RGB to shop A. Shop A to Shop B using Absolute Colorimetric intent. The matching should be much closer.

3

Thanks for the reply. I think I tried exactly what you’ve suggested. I got a much closer match going straight from RGB to my printers CMYK colorspace.

Heres the situation. A photographer likes to work in Colormatch RGB and outputs to his Epson 4800 (with K3 inks) thru a Colorburst rip to simulate DTR004 on Epson Premium Semimatte paper.(the paper profile is canned)

The client OKs the color on his proof.

I then get the same RGB file(Colormatch embedded) and need to match his color print on my Epson 9600 with Ultrachrome ink and Kodak IRIS pro semimatte paper.(custom paper profile)

I convert the RGB file “relative” to his supplied DTR004 CMYK profile, then convert “relative” to my CMYK press profile, and proof thru BestColor rip to my 9600 to simulate what the color will look like on our press.

This result is a lot worse than if I just convert from RGB Colormatch-“relative” to my CMYK press profile. I’m hoping a slight curve adjustment in Photoshop will get me pretty close.

I thought I have tried different rendering intents and will give “absolute” a try as you suggest. At least my understanding of color management is correct in theory. Also, even though the gamuts and the papers are different, shouldn’t the color management compensate for these differences?

Thanks again for the timely reply!