[argyllcms] Re: testing printer profile with a set of XYZ colours
- From: Gerhard Fuernkranz <nospam456@xxxxxx>
- To: argyllcms@xxxxxxxxxxxxx
- Date: Sat, 29 Jan 2011 11:42:02 +0100
Am 29.01.2011 01:42, schrieb Iliah Borg:
> Dear List,
>
> 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
>
> Next, for those XYZ that fall into the gamut I convert them to RGB
> xicclu -fb -ip -pX
>
Why "-ip" and not "-ia"?
As perceptual intent is supposed to do gamut mapping (and possibly to
include other "artistic" transformations), the measured XYZ numbers of
the printed patches are not expected at all to match the original
numbers when using "-ip".
Or is your goal to verify how well perceptual intent still reproduces
those colors (albeit it is not expected to reproduce them exactly)? But
in this case I'd possibly rather tend not to compare the measured XYZ of
the printed patches directly with the original XYZ numbers, but to do
this comparison in a white-point relative manner (i.e. convert the
measured numbers with a CAT paper white to D50, before comparing them to
the original numbers), because perceptual is basically expected to map
source WP to destinatino WP as well. But how to do it depends all on
your exact intention, of course...
Regards,
Gerhard
> 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.
>
> Any better ideas, suggestions, improvements, please?
>
> --
> Iliah Borg
> ib@xxxxxxxxxxx
>
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