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I use QTR-Create-ICC-RGB.exe to create icc's for soft proofing my alt process prints, and have been doing so for many years. After I do a calibration, I make a calibrated negative with a step table that goes from 0 to 255 in steps of 5 RGB units (0, 5, 10, ... 255). I measure the print with a Spyder and then drag the Spyder output file onto the QTR-Create-ICC-RGB.exe, which creates the icc profile. This has always worked and has given me very reliable soft proofs for cyanotype, vandyke, and kallitype.

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Today, I printed a color step table, not with a digital negative, but rather with my inkjet printer. I wanted to see if I could make an icc profile that I could use to simulate printing color separations.

I measured the print with my Spyder and dragged the Spyder output file onto QTR-Create-ICC-RGB.exe. The QTR-Create output file shows that the L values linear, but the A and B values are all zero!?

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What am I doing wrong?

I only used only 16 Lab values, which apparently isn't enough for an icc. I couldn't find any documentation regarding a minimum.

I just tried again using 51 Lab measurements (file attached), which is the same as I usually do. But again, QTR-Create-ICC RGB (version 2.7.9.0) produces what looks like a grayscale icc profile (out file attached).

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Roy,

Thank you. That worked!