[argyllcms] Re: testing printer profile with a set of XYZ colours
- From: Klaus Karcher <lists@xxxxxxxxxxxxxxxxx>
- To: argyllcms@xxxxxxxxxxxxx
- Date: Sat, 29 Jan 2011 11:29:52 +0100
Hi Iliah,
you wrote:
Suppose I need to check a printer profile for reproduction of a set
of about 500 pre-determined colours; colours being defined as XYZ D50
2 degree.
As a first step, I filter off the colours that are out of gamut
using xicclu -fif -ia -pX
This is a pragmatic way to check if the colors are in gamut. I tried out
others, but came back to it as it is quick and easy.
Please note that you have to use -fb (lower precision) or specify the
original separation parameters if you want to use them with xicclu -fif.
Otherwise you use xicclu's defaults (-kr, estimated TIL, no black ink
limitation). Separation parameters may affect the gamut, especially in
dark areas.
Next, for those XYZ that fall into the gamut I convert them to RGB
xicclu -fb -ip -pX
Why perceptual? Do you want to investigate gamut mapping?
From the RGB list I
make a target formatting to CGATS and using ColorPort, print it,
measure it, and compare resulting XYZ numbers to source XYZ.
I'm not quite sure what you are after. If it's just the profile you want
to test, I'd skip the printing and measurement part and just complete
ther "round trip" with another xicclu call. Otherwise you bring
additional unknowns into play (printer repeatability, measurement
uncertainty)
If you really want to test the complete workflow, you can of course also
use Argyll's tools (printtarg and chartread) to create and measure the
target.
Klaus
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