Pascal de Bruijn wrote:
I've more or less asked about this in the past, but I gave up on it, back then... I have two images of an IT8 chart... 1. A digital camera generated JPG (white-balanced, and gamma corrected) 2. A RAW file, converted to JPG (white-balanced, but not gamma corrected, so it's linear RGB) Both images, are in fact, the same image, just stored in a different way... I'd like to generate a profile, which would turn my nr 2 image into something very close to my nr 1 image. Is this possible? Can anybody help me with accomplishing this?
Ok, I think finally I got what you try to achieve: your "image 1" is no faithful reproduction, but you like the "look" you get when using workflow 1 and want to obtain the same biased result with workflow 2.
Provided that the workflows are deterministic, you can create a profile for workflow 2 that largely replicates the "look" (or errors from a colorimetric point of view) of workflow 1.
What you need is a profile built from a "faked" ti3 file. This file has to link the device values of image 2 with cie values calculated from image 1 with profile 1.
There are several ways to achieve this. I want to outline one of them using scanin and fakeread.
Klaus
# image1.tif and image2.tif are images of a ColorCheckerSG # processed with workflow 1 and workflow 2 # read the device values from image1: scanin -dipn image1.tif ColorCheckerSG.cht ColorCheckerSG.cie diag.tif # image1.ti3 contains device values from image 1 # and cie values from ColorCheckerSG.cie # the cie values in ColorCheckerSG.cie are trivial # as we replace them later anyway # create ti1 for fakeread cp image1.ti3 fake.ti1 # change line 1 of file fake.ti1 from "CTI3" to "CTI1" and # line 9 from # COLOR_REP "XYZ_RGB" # to # COLOR_REP "RGB" # create ti2 for fakeread cp fake.ti1 fake.ti2 # change line 1 of file fake.ti2 from # CTI1 # to # CTI2 # add column "SAMPLE_LOC" to file fake.ti2 # (contents depends on your cht file) # example for ColorCheckerSG: # before: # ... # NUMBER_OF_FIELDS 10 # BEGIN_DATA_FORMAT # SAMPLE_ID XYZ_X XYZ_Y XYZ_Z RGB_R RGB_G RGB_B STDEV_R STDEV_G STDEV_B # END_DATA_FORMAT # # NUMBER_OF_SETS 140 # BEGIN_DATA # A01 89.130 92.990 75.770 98.873 99.556 99.984 0.23857 0.15282 0.19374 # A02 0.80000 0.84000 0.70000 7.3287 6.6960 7.3602 1.3017 1.3735 1.2807 # A03 18.560 19.270 15.790 44.461 48.695 55.216 0.41040 0.28607 0.27125 # ... # after: # ... # KEYWORD "SAMPLE_LOC" # NUMBER_OF_FIELDS 11 # BEGIN_DATA_FORMAT # SAMPLE_ID SAMPLE_LOC XYZ_X XYZ_Y XYZ_Z RGB_R RGB_G RGB_B STDEV_R STDEV_G STDEV_B # END_DATA_FORMAT # # NUMBER_OF_SETS 140 # BEGIN_DATA # A01 A1 89.130 92.990 75.770 98.873 99.556 99.984 0.23857 0.15282 0.19374 # A02 A2 0.80000 0.84000 0.70000 7.3287 6.6960 7.3602 1.3017 1.3735 1.2807 # A03 A3 18.560 19.270 15.790 44.461 48.695 55.216 0.41040 0.28607 0.27125 # ... # use fakeread to read the cie values for image 1 as "seen" by profile1 fakeread profile1.icc fake # fake.ti3 now contains device values from image 1 # and corresponding cie values calculated with profile1.icc # use scanin to replace device values in fake.ti3 # with device values from image2 scanin -r -dipn image2.tif ColorCheckerSG.cht fake diag.tif # modify file fake.ti3 # change DEVICE_CLASS "DISPLAY" # to DEVICE_CLASS "INPUT" # and COLOR_REP "RGB_XYZ" # to COLOR_REP "XYZ_RGB" # create your fake profile colprof fake # when you assing fake.icc to image2.tif, # it shold look largely like image1 with profile1
