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Digital Silver Gelatin Prints
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PostPosted: Fri Aug 10, 2018 12:32 am    Post subject: Digital Silver Gelatin Prints Reply with quote

I have never seen a digital print that can match the beauty of silver gelatin print, so I've been working on a hybrid approach. (This relates only to BW photography).

I take a digital shot of a standard gray scale. I invert the scale in a digital darkroom (although that's probably not necessary), and print it on clear acetate (i,e, a blank vugraph). I now have a "negative ", and I make a contact print. Next step entails running a densitometer over each tone in the gray scale, and comparing the values. The ratio of actual density to desired density is then used to design an adjustment curve, and I repeat the process. In theory, I should get a perfect gray scale. And if I then print a negative of a real picture using the revised gray scale, it should have exactly the tones that I expected, and I can make a silver contact print. This would not only be esthetically more satisfying, silver gelatin prints sell for a lot more than giclee prints.

Unfortunately the process hasn't been working. After I print the gray scale with the revised curve, it's still not a real gray scale. I have no idea why. Anybody got any ideas or suggestions?


PostPosted: Fri Aug 10, 2018 8:07 am    Post subject: Reply with quote

Welcome here!

Maybe have a look at our member Dan_ work, he does printing, now also using alternate processes up to platinum printing.

Look here: http://forum.mflenses.com/platinum-palladium-prints-t78974.html


PostPosted: Sun Aug 12, 2018 12:05 pm    Post subject: Reply with quote

Welcome to the forum, js!

Could you please be more specific on how have you counted the correction curve? Post some screenshots with the measured values curve and the computed correction curve if you can, too.

You want to match the printed image with the image you see on your monitor. There is no need for a digital shot of the standard gray scale - just print a transparency film negative of the standard gray scale file opened in PS and then contact-print it on photographic paper.
The camera may have hidden inner settings that can distort the result.
If your grayscale doesn't have a file to open in PS then just make a grayscale step-wedge with 16 (curves may only have 16 building points) equidistant gray values from 0 to 255 (with a step of 17) and print a negative of it. It's even better to do so.

Some general considerations:
- Not all transparency films and all printer inks are equally good for DNs. Pictorico transparency film and Epson inks are usually recommended.
- Using more of the printer inks, not only Ks, to print the DN should result in smoothest tonal gradations and minimum grain. The photographic paper has different sensibilities to different coloured light. You could check for the color that gives the better tonal gradations and print the DN using it.
- Using reflection or transmission densitometers require different approaches for correctly translating the redings into % (or 0-255 ) values in PS.
- You could check your correction curve by "adding" the readings curve and correction curve. The result should be a "diagonal curve". I have written a PS script for "adding" 2 PS curves. You can find it here:
https://drive.google.com/file/d/1VTeIOxOzSoXP4o7NuJGQkq8RFrHTZZOQ/view?usp=sharing