Soft proofing with a PiezoDN ICC profile


This is a practical question about how to use PiezoDN ICC profiles to soft proof an image in Photoshop. I’m on Windows.

I have successfully linearized a process (New Cyanotype), made an ICC profile using QTR-Create-ICC.exe, and installed it.

To prepare an image for printing a negative, I open the image in Photoshop, duplicate it, and then configure tabs with the original image on the left and the copy on the right. I flatten the copy and convert it to Grayscale Gamma 2.2. With the copy selected,

View -> Proof setup -> Custom…
Check Preserve Numbers
Select the ICC profile
Leave both Display Options unchecked

The copy turns Prussian Blue and the tonal range becomes significantly compressed. I assume Photoshop is showing me approximately what the darkroom print will look like if I do nothing (I say “approximately” because, although my monitor is calibrated, I can’t claim to have a perfectly color-managed workflow with a D50 viewing environment, etc., etc.). But at least the darkest tone in the copy should correspond to dMax in the print and the lightest tone of the copy should correspond to dMin in the print. I don’t know how to verify this because the info panel shows the underlying numbers, rather than the actual tones on the screen.

I make changes to the copy. For example, I add an “S” curve to recover lost contrast in the midtones.

I save the copy as a Photoshop document with “-proof” added to the filename. This file will be the basis for all negatives that I make.

To make a negative of a particular size, I open the “-proof” document, flip horizontally, scale it, change the canvas size, and save as a .tif file. In the Save as dialog, I uncheck Layers and Alpha channels. I could also uncheck ICC Profile (which would save the .tif without an embedded profile), but I have been leaving Profile checked. I hope this is not a problem.

I open the .tif in QTRGui and choose the linearized quad. There is no ICC profile option in QTRGui, so I expect QTRGui to use the numbers in the document, interpreting them as Gray Gamma 2.2. I print a negative and then make a darkroom print.

My question: if I follow this workflow, should the darkroom print approximately match the proof copy on the screen?


Yes. This workflow is the “linear workflow” to a T. It should be a decent match.