> Also, I've just read two of Ansel Adams books on the Zone System and would
> like to talk - off line - to anyone who can help me extrapolate this to
> the pictures that I take. Specifically, I'd like to:
>
> 1. scan a photograph or negative into my computer (not a problem)
> 2. convert the RGB values to % gray (I do not understand how to do this.)
> 3. convert the % gray to zones (I think I understand how to do this, but
> I'd like some confirmation.)
> 4. print out the pictures in zones of gray for further study. (Not sure
> that monitor RGB and printer density relate to %gray in the same manner.)
Hey, some use for my digital skills! (I knew all that camera and software
designing would pay off someday ;-). In PhotoShop 5.0, here's what you'd do:
1. Get your photo into the computer (I scanned one in using my Nikon slide
scanner).
2. Select Image/Mode/Grayscale to convert the image to black and white.
3. Select Image/Adjust/Posterize and specify 10 levels. This doesn't get you
perfectly down to only 10 levels (zones), but it gets you close enough for
what you want to do, I believe. You can see exactly what's happening by
selecting Image/Histogram. (If for some reason you really want to reduce the
palette down to only 10 values, let me know. You'll need to do some extra
work to create a 10-value color table, and we'll need to discuss the various
"reduction" mechanisms PhotoShop uses, as they will have a definite impact
on the results.)
For what it's worth, I took one of my photos from an F5 down to 10 pixel
values just for the heck of it, and the results were pretty interesting. The
photo is still quite recognizable (just looks "grainy"), but it's also very
clear where you should meter it with a spot meter. Anyone who'd like to see
the results should email me privately.
Thom Hogan
Executive Editor, BACKPACKER Magazine
author, The Nikon Field Guide (Silver Pixel Press)
www.bythom.com
