[argyllcms] Re: printer profiles - how to get max black
- From: "Mike Russell" <groups@xxxxxxxxxxxxxxxx>
- To: <argyllcms@xxxxxxxxxxxxx>
- Date: Wed, 6 Dec 2006 15:28:12 -0800
Mike Russell wrote:
I'm successfully making RGB profiles for my printers, using a DTP22,
"Graeme Gill" wrote::
Is it a DTP22 or a Digital Swatchbook (ie., what's printed on the top
of the instrument ?). I got as far as getting the Digital Swatchbook
that I happen to have working directly with Argyll, although the
instrument
refuses to calibrate. I haven't quite finished adding the support for
an instrument that only operates correctly using it's built in switch
though.
It says Digital Swatchbook on the top. I'd be glad to try out the software.
One remaining problem - the profiles I create are satisfactory, but for
one
of my printers the PCS value for black, Lab(0,0,0), yields an RGB value
of
RGB(13,8,2). This is very close to black, but measures as a slightly
lower
density than a max black. The profile is probably attempting to
compensate
for the rather cool black of this printer by adding red-orange. Is there
a
way that I can specify that black should map to RGB(0,0,0)?
The general behaviour of the B2A tables is that any out of gamut colors
(after
any gamut mapping) will be mapped to the closest perceptual color. You
don't say
which intent (if any) you are dealing with, and without the .ti3 and/or
the profile, it's hard to be more specific. Normally this will be the
blackest
possible color, since black is usually a "cusp", and the closest distance
from
a point some distance away (like Lab(0,0,)) is the cusp.
This happens for all intents (perceptual, relcol, saturation, and abscol)
with and without Photoshop's black point compensation enabled. I've
attached the ti3 and the profile, and the output from the profile
command.follows. If you have time to look any of this over, that would be
great. BTW - I'm sure I'm not alone when I say I'm impressed and delighted
by the level of your support, Graeme.
Mike
E:\Pix\Calibration\Epson_670>profile -v -qm -S
sRGB.icm -cmt -dpp -A"Epson" -M ESCP -D"Epson 670 glossy" -C "Copyright (c)
2006 Mik
Russell" Epson_760_glossy
No total ink limit being used
No black ink limit being used
No of test patches = 270
Estimating white point
Approximate White point XYZ = 0.897195 0.923850 0.808712, Lab = 96.977448
1.166931 -3.894359
Creating optimised input and output curves
About to optimise temporary matrix
...........
About to optimise input curves and matrix
.......................................................................................
About to optimise output curves and matrix
...................................................................................................................................................................................................
About to optimise input curves and matrix again
.............................................
About to optimise input, matrix and output together
...........................................................................................................................................
About to adjust a and b output curves for white point
Creating fast inverse input lookups
Compensate scattered data for input curves
Compensate scattered data for output curve
Create clut from scattered data
***********************************************************************************************************************************
***********************************************************************************************************************************
***********************************************************************************************************************************
*****
Find white & black points
White point XYZ = 0.897994 0.922865 0.804872, Lab = 96.937305
1.484920 -3.648572
Black point XYZ = 0.004298 0.004571 0.006182, Lab =
4.129097 -0.440210 -4.553000
Fixup clut for white point
Check White point XYZ = 0.897994 0.922865 0.804872, Lab = 96.937304
1.484920 -3.648572
Done A to B table creation
Creating B to A tables
Creating Gamut Mapping
Finding Source Colorspace Gamut
Finding Destination Gamut
Creating Gamut match
gamut_match parameters:
Grey axis hue matching factor: 1.000000
Grey axis luminance white compression factor: 1.000000
Grey axis luminance white expansion factor: 1.000000
Grey axis luminance black compression factor: 1.000000
Grey axis luminance black expansion factor: 1.000000
Grey axis luminance knee factor: 1.000000
Gamut compression factor: 1.000000
Gamut expansion factor: 0.000000
Gamut knee factor: 0.500000
Gamut mapping Perceptual Mapping weighting factor: 1.000000
Gamut mapping Saturation Mapping weighting factor: 0.000000
Saturation enhancement factor 0.000000
Gamut map resolution: 25
Neutral axis no-adapt extend and bend
Src colorspace white/black are 100.000000 -0.740073 1.779114,
11.133921 -0.242270 0.582408
Src gamut white/black are 100.000000 -0.740073 1.779114,
11.133921 -0.242270 0.582408
Dst colorspace white/black are 100.000000 -0.525331 1.216409,
10.905464 -1.728861 -4.195125
Target (blended) dst wp/bp = 100.000000 -0.525331 1.216409,
10.905464 -1.728861 -4.195125
Adapted target wp/bp = 100.000000 -0.525331 1.216409,
13.449557 -0.226335 0.537847
Adapted & extended tgt wp/bp = 100.000000 -0.525331 1.216409,
10.905464 -0.217546 0.517901
Bend target bp =
10.905464 -1.728861 -4.195125
Rotate matrix src wp/bp = 100.000000 -0.740073 1.779114,
10.911669 -0.241025 0.579415
Rotate matrix dst wp/bp = 100.000000 -0.525331 1.216409,
10.905464 -0.217546 0.517901
Rotated source grey axis wp/bp 100.000000 -0.525331 1.216409,
11.127731 -0.218314 0.519643
Rotated gamut grey axis wp/bp 100.000000 -0.525331 1.216409,
11.127731 -0.218314 0.519643
Destination axis target wp/bp 100.000000 -0.525331 1.216409,
10.905464 -0.217546 0.517901
Mapped source grey axis wp/bp 99.997440 -0.525323 1.216389,
10.918888 -0.217592 0.518006
...............
White is 99.984020 -0.373346 1.192742, should be 100.000000 -0.525331
1.216409
Black is 10.991914 -1.398624 -3.200911, ideal is
10.905464 -1.728861 -4.195125
After fine tuning:
White is 99.999998 -0.525331 1.216409, should be 100.000000 -0.525331
1.216409
Black is 10.991914 -1.398624 -3.200911, ideal is
10.905464 -1.728861 -4.195125
gamut_match parameters:
Grey axis hue matching factor: 1.000000
Grey axis luminance white compression factor: 1.000000
Grey axis luminance white expansion factor: 1.000000
Grey axis luminance black compression factor: 1.000000
Grey axis luminance black expansion factor: 1.000000
Grey axis luminance knee factor: 1.000000
Gamut compression factor: 0.900000
Gamut expansion factor: 1.300000
Gamut knee factor: 1.000000
Gamut mapping Perceptual Mapping weighting factor: 0.000000
Gamut mapping Saturation Mapping weighting factor: 1.000000
Saturation enhancement factor 0.800000
Gamut map resolution: 25
Neutral axis no-adapt extend and bend
Src colorspace white/black are 100.000000 -0.740073 1.779114,
11.133921 -0.242270 0.582408
Src gamut white/black are 100.000000 -0.740073 1.779114,
11.133921 -0.242270 0.582408
Dst colorspace white/black are 100.000000 -0.525331 1.216409,
10.905464 -1.728861 -4.195125
Target (blended) dst wp/bp = 100.000000 -0.525331 1.216409,
10.905464 -1.728861 -4.195125
Adapted target wp/bp = 100.000000 -0.525331 1.216409,
13.449557 -0.226335 0.537847
Adapted & extended tgt wp/bp = 100.000000 -0.525331 1.216409,
10.905464 -0.217546 0.517901
Bend target bp =
10.905464 -1.728861 -4.195125
Rotate matrix src wp/bp = 100.000000 -0.740073 1.779114,
10.911669 -0.241025 0.579415
Rotate matrix dst wp/bp = 100.000000 -0.525331 1.216409,
10.905464 -0.217546 0.517901
Rotated source grey axis wp/bp 100.000000 -0.525331 1.216409,
11.127731 -0.218314 0.519643
Rotated gamut grey axis wp/bp 100.000000 -0.525331 1.216409,
11.127731 -0.218314 0.519643
Destination axis target wp/bp 100.000000 -0.525331 1.216409,
10.905464 -0.217546 0.517901
Mapped source grey axis wp/bp 99.997440 -0.525323 1.216389,
10.918888 -0.217592 0.518006
.........................
White is 99.969041 -0.337555 1.304014, should be 100.000000 -0.525331
1.216409
Black is 10.975332 -1.305223 -2.917837, ideal is
10.905464 -1.728861 -4.195125
After fine tuning:
White is 100.000002 -0.525331 1.216409, should be 100.000000 -0.525331
1.216409
Black is 10.975332 -1.305223 -2.917837, ideal is
10.905464 -1.728861 -4.195125
100%
Done B to A tables
Creating gamut boundary table
100%
Done gamut boundary table
profile check complete, peak err = 6.237206, avg err = 1.978575
E:\Pix\Calibration\Epson_670>
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