Hi,
Few years back...
I was working in the colour management of printing presses and inkjet proofing.
In short I used to make the colour proofs supplied to the customer, match a
printing press.
And just about every printer, has digital printing as well.
I started by creating a test chart, this chart was to be used for profiling any
CMYK device.
In the printing world, there are lots on standards, but for a nice quality
print fogra39 was the standard at the time.
So I made a Argyll .ti1 that had the same patch count, and with excel, copied
the data from the fogra39 values.
Then made a i1 Pro chart and .ti2, fits on a A3 sheet, with the same CMYK
values as the published fogra39 standard.
The main point of this was to let me be able to check the final output, I would
use excel alot to look at the results.
I could open the measured ti3 file in excel, copy the lab values into a
spreadsheet and would work out the dE values.
I always found that looking at the CMYK values vs the dE values, very helpful
in looking for ways to improve the match.
I found this chart to work well for digital printing, my profiles, I think I
should say, Graeme's profiles have always produced better results.
Happy to share my excel files and chart files if anyone wants....
This made me think about trying to create some kind of RGB chart and reference.
And the big difference is it would need to be designed, with CMYK output in
mind.
This turned out to be quite a task...
After much thought... I made a CMYK profile using Fogra39 data and sRGB for
gamut mapping.
Then used icclu to convert the RGB values into real lab values. (I think this
was a few steps)
So I had L95 A0 B-2 for my RGB white point and about L8 for RGB blacks.
I did some tests with my rip set to absolute, and looked ok...
It was a good exercise at the time, and never did use it to measure and check
what is RGB output on a CMYK device.
Regards,
Mark Houghton
P.S. Graeme... Your gamut mapping rocks!
