Wednesday, April 11, 2012

Calibration Project Competed!

Again, the best source for the description and control of the process in my opinion is Ron Reeder, cited earlier.

The multi-ink curve which currently works for me sets a limit on the dark inks at 20 and the light inks at 24. This is up from the 14-18 at which I started. I found this through printing of various settings from 14-18 to 20-24 (otherwise known as trial and error). I started with a gamma setting of "1" rather than "0.7" which in preliminary trials did not work well for me. The setting of the correction curve in fact took care of the gamma and the crossover point. I found I was able to "tweak" the curve to adjust for slight anomalies of smoothness in the almost-right print ranges. But only very small changes can be implemented at this stage.

There are still some small deviations from the ideal step wedge in the lightest ranges of the positive print, but I find them tolerable, even preferable, on the test prints of actual subjects that I've run. I've tended to accept less-than-white-white on previous curves and enjoy the entire range from bright white to black black. In the future I may want to try to smooth out the range from 85-100 on the positive print. The blacks run to black a little too quickly from 88-96 for example, so I might lose some details in the deep shadows of the positive print. But overall, I'm quite satisfied with the tonal range -- and with the palladium printing technique.

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