[argyllcms] using targen with an existing profile
- From: "Roberto Michelena" <colorsync@xxxxxxxxx>
- To: argyllcms@xxxxxxxxxxxxx
- Date: Mon, 22 May 2006 00:56:20 -0500
I am not getting from Targen what I expected...
I have a good profile built from a lot of patches. The original
patches are spread regularly in device space (typical chart generated
by Gretag's MeasureTool), so when I plot them in Lab space (the
measurements of course), I can see there's a high concentration around
the black point (more than needed, tightly spaced) and there's an
insufficient concentration around the saturated greens and other
saturated gamut-edge colors.
So I guessed if I used Targen with the "-c" option, feeding it this
existing profile, it would distribute points more evenly accross Lab
space; including less redundancy in dark zone, and tighter sampling of
saturated colors.
I used:
targen -v -d 4 -e 6 -s 21 -f 4096 -l 260 -c existingprofile.icc
newargyll4000target
I got this feedback:
CMYK test chart
Single channel steps = 21
Full spread patches = 4096
Multi-dimention steps = 2
Ink limit = 260.000000%
Added fixed 103/104
Stats after fixed points:
Min = 0.000000, Average = 0.346665, Max = 0.870153
Percep: Min = 0.000000, Average = 0.346665, Max = 0.870153
Added 4091/4091
Stats after seeding points: Min = 0.000000, Average = 0.091043, Max = 0.124567
Percep: Min = 0.000000, Average = 0.105217, Max = 0.124567
Maxmv = 0.052702, stats Min = 0.000000, Average = 0.087823, Max = 0.125640
Percep: Min = 0.000000, Average = 0.103949, Max = 0.125640
<snip> (lots of similar lines here)
Maxmv = 0.028011, stats Min = 0.000000, Average = 0.084287, Max = 0.122479
Percep: Min = 0.000000, Average = 0.102928, Max = 0.122479
Stats after opt: Min = 0.000000, Average = 0.084287, Max = 0.122479
Percep: Min = 0.000000, Average = 0.102928, Max = 0.122479
Total number of patches = 4096
Execution time = 1878.890000 seconds
(a whole half hour to generate a target!)
The surprise came when I fed the resulting CMYK points through the
profile, and then plotted the resulting Lab values in 3D, comparing
against the previous dataset and the existing profile.
The points are sampling a smaller volume! except for the primaries
ramps which I specified, there are no points sampling the borders of
the gamut; all of them are many dE to the inside.
What am I doing wrong?
best regards,
-- Roberto Michelena
Infinitek
Lima, Peru
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