RE: uncurve/curve comparison on Loris' website
Don, (1) I agree. My suggestion was assuming Chales doesn't want to go back to recalibrate each primary color individually but solve the problem pragmatically -> still using those curves. He says that his calibrations for each primary color is good -> if he does something wrong, that should be the pigment concentration... I don't know if it's enough to simply re-establish a new standart printing time when cutting back the pigment amount, but I feel like that won't be enough (= probably curves also will have to change). And if it's that way, then he'll need to go back to the long / laborious process of recalibrate... I would definitely try what I suggested and see if that gives satisfactory-to-me results. If yes, I would never go back to recalibrate since I'm more interested in making images instead of making images *in the absolutely correct way*. (Don't take it like I'm not interested in the latter at all, I just give more importance to be able to put my vision on paper...) (2) Yes indeed. But since Charles said that the only way of getting paper white with his printer (R1800) was using all inks grayscale negatives, I simply trust him. AFAIK, R1800 are not the best in the domain of UV blocking... That leaves him the only option of reducing the ES of his coating solutions (where available), which translates to "use less dichromate" and/or "use more pigment" in gum printing. Since we already suspect that his pigment concentrations are higher than what is needed, then using less dichromate looks like a sound advice to me. Regards, Loris. -----Original Message----- From: Don Bryant [mailto:dsbryant@bellsouth.net] Sent: Friday, September 28, 2007 3:05 PM To: alt-photo-process-l@usask.ca Subject: RE: uncurve/curve comparison on Loris' website Loris, > Charles if that also doesn't work, don't overlook my suggestion of a levels / gamma adjustment channel before making separations (in luminosity mode -> thanks Michael)... > (1) I have to say, IMO that I regard this as a poor approach to solving the problem. Better to get the curves correct (if one is using curves). > BTW, what dichromate concentration are you using? You may try to use less dichromate if you use saturated solutions. That way, you may achieve paper white with colorized negatives (despite their DR being lower compared to grayscale / all-inks negatives). > (2) You can achieve paper white with saturated dichromate using colorized negatives. Don
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