problems with create-icc-rgb
2007-05-29 by Daniel Jackson
I'm trying to use QTR's create-icc to linearize my workflow for UT7 inks. I'm not yet using QTR itself (see my other post -- I'm hoping someone will tell me why I should be!). Instead, I'm following Paul Roark's recipe for combining a linearization with a Photoshop curve (http://www.paulroark.com/BW-Info/Embedding_Photoshop_Curves_in_ICCs.pdf). It seems to almost work. The problem is that the resulting ICC profile seems to be rather non-linear at the high density end, and my shadows get blocked up. I have tried both the 21 step and 51 step targets, and I have the same problem with each. I'm using a PrintFIX Pro spectrometer and its measure tool to generate the input for create-icc. Any idea what's going on? Has anyone seen this problem before? I'm appending the output of create-icc when I give it readings taken on a second printing of the target in which the new profile has been applied. My understanding is that this should be linear, but it seems to be far from it. --Daniel Step Dens Lab A B 0.00 0.054 95.27 1.56 -0.84 - b | a L + 2.00 0.073 93.72 1.68 -0.19 - b| a L + 4.00 0.090 92.22 1.74 0.49 - |b a L + 6.00 0.106 90.92 1.80 1.02 - | b a L + 8.00 0.127 89.19 1.89 1.78 - | b L + 10.00 0.150 87.41 2.04 2.23 - | b L + 12.00 0.164 86.31 2.06 2.97 - | a b L + 14.00 0.183 84.79 2.17 3.38 - | a b L + 16.00 0.208 82.85 2.30 3.93 - | a b L + 18.00 0.228 81.36 2.37 4.47 - | a bL + 20.00 0.251 79.66 2.46 4.93 - | a L b + 22.00 0.275 77.94 2.51 5.40 - | a L b + 24.00 0.295 76.53 2.61 5.90 - | a L b + 26.00 0.323 74.53 2.69 6.12 - | a L b + 28.00 0.350 72.68 2.79 6.51 - | a L b + 30.00 0.373 71.15 2.85 6.72 - | aL b + 32.00 0.400 69.33 2.88 6.87 - | a b + 34.00 0.419 68.10 2.91 7.07 - | La b + 36.00 0.444 66.53 2.95 7.22 - | L a b + 38.00 0.485 63.93 3.05 7.42 - | L a b+ 40.00 0.513 62.27 3.04 7.44 - | L a b+ 42.00 0.542 60.53 3.08 7.60 - | L a b 44.00 0.571 58.86 3.12 7.55 - | L a b 46.00 0.598 57.28 3.13 7.52 - | L a b 48.00 0.619 56.11 3.10 7.50 - | L a b 50.00 0.644 54.78 3.13 7.48 - | L a b+ 52.00 0.683 52.70 3.12 7.37 - |L a b+ 54.00 0.726 50.46 3.11 7.15 - L a b + 56.00 0.779 47.78 2.96 6.82 - L | a b + 58.00 0.821 45.77 2.85 6.52 - L | a b + 60.00 0.841 44.84 2.82 6.35 - L | a b + 62.00 0.889 42.65 2.71 5.95 - L | a b + 64.00 0.915 41.49 2.64 5.75 - L | a b + 66.00 0.941 40.34 2.51 5.27 - L | a b + 68.00 1.003 37.73 2.33 4.30 - L | a b + 70.00 1.043 36.08 2.11 3.73 - L | a b + 72.00 1.087 34.37 1.92 3.10 - L | a b + 74.00 1.153 31.87 1.67 2.39 - L | a b + 76.00 1.207 29.92 1.47 1.79 - L | a b + 78.00 1.252 28.37 1.23 1.43 - L | ab + 80.00 1.298 26.84 1.31 1.47 - L | b + 82.00 1.331 25.75 1.24 1.51 - L | a b + 84.00 1.360 24.83 1.27 1.59 - L | ab + 86.00 1.413 23.21 1.17 1.59 - L | a b + 88.00 1.478 21.31 1.14 1.54 - L | a b + 90.00 1.503 20.59 1.03 1.56 - L | a b + 92.00 1.550 19.31 1.01 1.34 - L | ab + 94.00 1.582 18.45 1.07 1.21 - L | b + 96.00 1.598 18.02 1.00 1.00 - L | b + 98.00 1.599 18.00 1.00 1.13 - L | b + 100.00 1.605 17.83 0.97 1.06 - L | ab +