U of S | Mailing List Archive | alt-photo-process-l | Re: Gum Calibration 2 (How to read color samples?)

Re: Gum Calibration 2 (How to read color samples?)

Hi Loris,

Your idea sounds good, however it doesn't fit with the instructions which come with the product and I haven't tried it. Give it a whirl and let us know how it goes. The problem I have with both these pieces of software is that, yes you get a good curve for each individual colour and yes you will get a fully tonal print from each colour, but when you lay one coat upon another all bets are off. The resulting images (IMO) are far too dark/dense.

Good Luck though

David H

On Oct 24 2008, Loris Medici wrote:

This goes to those who calibrate with PDN / ChartThrob and use a scanner
for making readings from the printed step tablet:

What adjustment(s) you do, to the scan of the step tablet? Do you
desaturate it only?

I will re-calibrate from scratch (and separately for each color), using
stock paint:gum solutions, that's why I'm asking...

I was thinking to change the image mode to Lab, split channels, and then
use the Luminosity image (mode changed to RGB) for taking the readings.
That way, the basis of the calibration would be Luminosity. That sounds
right to me, since we're trying to match both chroma and luminosity for a
good color balance, isn't it?

I just don't like the idea of desaturating, since it's not obvious how
Photoshop does it, and feel like it can give quite different results
depending on color... (I'm not sure saying that -> just a feeling ->
doesn't seem right.)

Any thoughts?

Thanks in advance,