[argyllcms] Creating process calibration curves Was: Conversion omitting/locking device colorant
- From: Martin Weberg <martin.weberg@xxxxxxxxx>
- To: argyllcms@xxxxxxxxxxxxx
- Date: Tue, 27 Jan 2009 08:45:44 +0100
List,
I thought I'd share a little session I had, using xicclu -kv, icclu
and Gnumeric.
Calibration print run on sheet-fed offset press using linear printing plates.
Within tolerances, match as much as possible to standard ISO 12647-2
PT 1&2 (i.e. prim./sec. colors, dot gain)
When dry create device profile from IT8.7/4 chart.
Then:
Target Lab at 25, 50 and 75 K:
icclu -ff -ia -s100 ISOcoated_v2_eci.icc
0 0 0 25
0.000000 0.000000 0.000000 25.000000 [CMYK] -> Lut -> 79.441962
-0.140086 -1.997727 [Lab]
0 0 0 50
0.000000 0.000000 0.000000 50.000000 [CMYK] -> Lut -> 61.806456
-0.147246 -1.553618 [Lab]
0 0 0 75
0.000000 0.000000 0.000000 75.000000 [CMYK] -> Lut -> 41.105493
-0.065598 -0.707456 [Lab]
Target CMY from target Lab:
xicclu -kv -ia -fif ISOcoated_v2_eci.icc
79.441962 -0.140086 -1.997727
79.441962 -0.140086 -1.997727 [Lab] -> Lut -> 0.221580 0.155773
0.166181 0.000000 [CMYK]
61.806456 -0.147246 -1.553618
61.806456 -0.147246 -1.553618 [Lab] -> Lut -> 0.454712 0.353944
0.356616 0.000000 [CMYK]
41.105493 -0.065598 -0.707456
41.105493 -0.065598 -0.707456 [Lab] -> Lut -> 0.720534 0.621456
0.619903 0.000000 [CMYK]
Device CMY needed to meet target Lab:
xicclu -kv -ia -fif Device_Profile.icc
79.441962 -0.140086 -1.997727
79.441962 -0.140086 -1.997727 [Lab] -> Lut -> 0.183225 0.121471
0.145808 0.000000 [CMYK]
61.806456 -0.147246 -1.553618
61.806456 -0.147246 -1.553618 [Lab] -> Lut -> 0.401252 0.306147
0.317546 0.000000 [CMYK]
41.105493 -0.065598 -0.707456
41.105493 -0.065598 -0.707456 [Lab] -> Lut -> 0.660704 0.547960
0.560626 0.000000 [CMYK]
Device K needed to meet L* of target K (iterative user input):
icclu -ff -ia -s100 Device_Profile.icc
0 0 0 21
0.000000 0.000000 0.000000 21.000000 [CMYK] -> Lut -> 79.440394
0.905778 -3.496105 [Lab]
0 0 0 43.5
0.000000 0.000000 0.000000 43.500000 [CMYK] -> Lut -> 61.842308
0.630904 -2.312832 [Lab]
0 0 0 66.8
0.000000 0.000000 0.000000 66.800000 [CMYK] -> Lut -> 41.070386
0.519650 -0.627445 [Lab]
CtP input/output needed:
Cyan
0 0
22,158 18,3225
45,4712 40,1252
72,0534 66,0704
100 100
Magenta
0 0
15,5773 12,1471
35,3944 30,6147
62,1456 54,796
100 100
Yellow
0 0
16,6181 14,5808
35,6616 31,7546
61,9903 56,0626
100 100
Black
0 0
25 21
50 43,5
75 66,8
100 100
Using data above and 3rd deg. poly. regression to calc full range of
smoothed CtP input/output tone values:
% C M Y K
0 0 0 0 0
5 4,2 4,1 4,5 4,6
10 8,4 8,3 9,0 9,0
15 12,6 12,4 13,4 13,2
20 16,9 16,6 17,8 17,4
25 21,2 20,8 22,1 21,6
30 25,6 25,1 26,5 25,7
35 30,0 29,5 30,9 29,8
40 34,5 33,9 35,4 34,0
45 39,1 38,5 39,9 38,3
50 43,9 43,2 44,6 42,6
55 48,7 48,0 49,3 47,2
60 53,7 52,9 54,2 51,9
65 58,9 58,1 59,2 56,8
70 64,2 63,4 64,4 61,9
75 69,6 68,9 69,7 67,4
80 75,3 74,6 75,3 73,1
85 81,1 80,6 81,1 79,2
90 87,2 86,8 87,1 85,7
95 93,4 93,2 93,4 92,5
100 100 100 100 100
Any thoughts about the process?
Martin Weberg
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