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Re: Digital Negatives with enough Tones for Pt/Pd
Jeffery,
Continuing to look into the method you have described regarding greater bit
color depth and the 8 bit printer depth limitation. Specifically, I'm
interested because I too have experienced some posterization in the
highlights - this has occurred on all of the medium I have printed on.
Actually, I am quite pleased with the Lightjet negs (finally), but the
expense/time lag are not so appealing. Also, at resolutions less than
upward of 400dpi (not sure where the precise number is yet) the Lightjet
exhibits some of the characteristics of the imagesetter output - ie lines
when viewed under magnification. Apparently, the higher the resolution the
more difficult it is to discern - I have asked for an example of these from
the lab, so that I can say for sure.
The text below was taken from the Photoshop 5.02 help file and it appears
that Photoshop will import or open a file with 16 bits per RGB channel for
48 total. The conversion of even an 8 bit file to a 16 bit mode (this would
work with my 8 bit scanner) would then allow the selection of the low, mid
and high tones that you spoke of, to be selected/deselected into 3 absolute
registration images that could be saved individually.
Actually, what I would be working toward is to two images instead of three -
low to mid and mid to high.
I'm not suggesting that this is an absolute analogy, but it seems that if it
works it
would take the mechanics of the scanner out of the picture (no pun). The
use of the levels, curves or transfer commands could then select the desired
info
for the final conversion to 8 bit for the printer. In reality, an "Action"
could be created to take any file and automatically create the desired
results - one for each of the areas required, be it 2 or more levels of
info.
Nick
>Note: A16-bit-per-channel image provides finer distinctions in color, but
its file size is much larger >than an 8-bit-per-channel image.
>Photoshop supports these tools and commands in 16-bit-per-channel images:
the marquee, lasso, >crop, measure, zoom, hand, pen, eyedropper, color
sampler, and rubber stamp tools; and the >Duplicate, Feather, Modify,
Levels, Auto Levels, Curves, Histogram, Hue/Saturation,
>Brightness/Contrast, Color Balance, Equalize, Invert, Channel Mixer, Image
Size, Transform >Selection, and Rotate Canvas commands. To take full
advantage of Photoshop's features, you can >convert a 16-bit-per-channel
image to an 8-bit-channel image.
>To convert from 8 bits per channel to 16 bits per channel:
>1 Flatten the image you want to convert, as explained in Flattening all
layers.
>2 Choose Image > Mode > 16 Bits/Channel.
>To convert from 16 bits per channel to 8 bits per channel:
>Choose Image > Mode > 8 Bits/Channel.