calling all photoshop gurus

Happy holidays to all,

Is there a way, in photoshop, to set a particular RGB tone (say 20, 20, 20) for shadows and another (say 220, 220, 220) for highlights and, in doing so, compress/expand the mid-tones to fit within those limits?

The reason behind this question is that for the past several years I have been trying, on and off, to make digital negatives for contact printing with out much success. I find that my inkjet negatives are either too contrasty or too flat for the processes I use. Last night I got the idea of making the negatives fit the process using conventional densitometry logic (increase exposure for shadow detail and decrease development for highlight control). So, I created a 256 tone grayscale stepwedge to test my idea. I chose to limit my tests to a particular media (Westjet film), a particular printer (Epson 1280), and a particular ink set (MIS dye inks). I printed four copies of the stepwedge as follows:

1 - 1440 dpi printer resolution (back light film), 480 dpi file resolution, 6 inks to make black
2 - 1440 dpi printer resolution (back light film), 480 dpi file resolution, black ink only
3 - 1440 dpi printer resolution (back light film), 240 dpi file resolution, 6 inks to make black
4 - 1440 dpi printer resolution (back light film), 240 dpi file resolution, black ink only

I then proceeded to take a densitometer reading for each step on each stepwedge and record the readings. (BTW, I found a maximum density of 2.86 with print 1.)

My theroy, being applied to a negative image, is that if I knew the tone of a particular shadow density (say 0.20 above media) and a particular highlight density (say 2.00 above media), resulting in a density range of 1.80, then I could then adjust the tones of the shadows and highlights of my image to fit a process requiring a density range of 1.80. Which returns me to my question of how to set the shadow and highlight tones.

As an aside, I found that print 4 (contacted with cyanotype) gave the smoothest gradation and the sharpest look.

Any help would be greatly appreciated,

Scott Wainer
smwbmp@starpower.net
Received on Tue Dec 23 19:35:48 2003