[argyllcms] Re: Absolute colorimetric - dark saturated colours excessively light
- From: Graeme Gill <graeme@xxxxxxxxxxxxx>
- To: argyllcms@xxxxxxxxxxxxx
- Date: Sun, 05 Feb 2006 02:14:16 +1100
Alastair M. Robinson wrote:
I should have been clearer here. Prism uses the scanner-as-colorimeter
trick, so this profile, unlike the others, was built using a scanner;
prism may well be over-optimistic about the strength of black (and a
print won't match this proof nearly as well as those created with the
Argyll-generated profiles)
OK - it's not a good comparison then.
Perhaps these two are better control subjects:
ISOuncoated:
http://i14.photobucket.com/albums/a346/robinsonb5/IT8_ISOuncoated.jpg
and
ICONSnewspaper26v5:
http://i14.photobucket.com/albums/a346/robinsonb5/IT8_Newspaper_Proof.jpg
The gamut-mapping strategy used by these two profiles appears to be to
preserve hue angle at all costs, and weight the saturation/luminance
balance in favour of preserving luminance.
I'm not clear - are these two Argyll profiles, or something else ?
Is there anything I could tweak to weight Argyll's strategy more towards
preserving luminance?
I guess I'm a little confused then. You were referring to absolute
colorimeter,
and there's nothing much to tweak there - you get clipping to the closest color.
If you're speaking of perceptual or saturation, then you can certainly play
with the numbers, although I'm not sure emphasizing the luminance any more
will be good. Some folks currently think that things are overly light,
and under saturated (e.g. blues and greens).
In gamut/gammap.c, change the #define P_A_LWEIGHT. (In the version I'm
currently working on, I've reduced the luminance weighting, to give a
little more saturation - along with rather a lot of other changes in
this area.)
Graeme Gill.
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