I need to explore the encoding of the A2B1 tag (CMYK to Lab).
I used the following command line :
iccdump -v3 -t A2B1 "myProfile.icc" > A2B1.txt
Works great, except, I'm having difficulty interpreting the data.
Here are the first 15 lines of the CLUT table (grid size = 16) :
CLUT table:
0 0 0 0: 0.9961089494 0.5000076295 0.5000076295
0 0 0 1: 0.9387197681 0.5011062791 0.4956588083
0 0 0 2: 0.8852063783 0.5021438926 0.4917830167
0 0 0 3: 0.8352941176 0.5031052110 0.4883649958
0 0 0 4: 0.7951628901 0.5039902342 0.4869916838
0 0 0 5: 0.7548180362 0.5048905165 0.4856183719
0 0 0 6: 0.7142290379 0.5057907988 0.4842298009
0 0 0 7: 0.6598306249 0.5077286946 0.4827649348
0 0 0 8: 0.6050812543 0.5096971084 0.4812695506
0 0 0 9: 0.5499809262 0.5116960403 0.4797589075
0 0 0 10: 0.4975814450 0.5110093843 0.4805981537
0 0 0 11: 0.4439612421 0.5102922103 0.4814068818
0 0 0 12: 0.3890287633 0.5095750362 0.4822156100
0 0 0 13: 0.3252460517 0.5079118029 0.4876173037
0 0 0 14: 0.2596475166 0.5062790875 0.4931868467
0 0 0 15: 0.1916075380 0.5046768902 0.4990005341
I take it that the first four digits of each line represent the CMYK value.
I can't tell whether the order in which the data is dumped here matches the
order in which the data is encoded in the tag?
For the first line of data, If I follow my intuition, I get 0c 0m 0y 0k.
In other words, this would be the unprinted media color (RelCol), which
should be Lab = 100, 0, 0. Right?
How do I interpret the corresponding Lab values :
0.9961089494 0.5000076295 0.5000076295
The first number, L*, seems awfully close to L = 100.
But how do I interpret the a* and b* values? The second and third numbers?
Do they have to be subtracted from some constant value? They can't be just
multiplied by 100?
Kindest regards / Roger