[argyllcms] Re: Creating process calibration curves Was: Conversion omitting/locking device colorant
- From: Roger <graxx@xxxxxxxxxxxx>
- To: argyllcms@xxxxxxxxxxxxx
- Date: Sun, 01 Feb 2009 13:45:06 -0500
Hi Martin,
I agree 100% with the method.
First fragen: have you tried the calculated calibration back on press? And
if so, what were the results?
Second fragen: where did you get "3rd deg. poly. Regression"? In Argyll?
Where?
MfG / Roger Breton
> 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
Other related posts:
