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Re: Multiple Colored Desktop Negatives
Garet Denise wrote:
> ... By replacing black with
> the appropriate shade (a reddish/orangish tone) problems
> with ink puddling and running can be reduced on plastic
> transparency materials, and the need for an adjustment curve
> is reduced. ...
This is true, however one must understand the ability of each ink (color
or black/gray) to provide tones with the particular printing process
used. For example, I have found that the magenta ink in the HP ink
cartridge C7568 only has a slight effect for Pt/Pd, while the yellow is
much better, and the cyan completely useless. The black ink (cartridge
HP-51645) works best but is not part of the HP-Ret ink deposit system.
It would be nice if there was a three gray cartridge for the
DeskJet-970. I am trying to work with the yellow and magenta, but am
limited by the transmission characteristics of the inks. Keeping in
mind that for negatives it is the transmission (not reflection) that is
important.
> The problem I have found (as described in a post several
> months ago) is that there is not enough separation in the
> shadows, and too much separation in the highlights. ...
>
> The obvious solution is to apply a curve in PhotoShop before
> printing the negative (using a single color). But the shape
> of the curve needed (at least in my case) is fairly radical,
> which results in ranges of tones being compressed
> (posterized) and loss of detail.
Certainly the same problem I have encountered.
> ... Why not use the
> Color Table to assign different shades to different tonal
> values and let PhotoShop interpolate the appropriate shades
> in between?
But this only produces, at most, 256 unique tones. To get more,
multiple negatives will still be needed.
I have also become more skeptical that even 256 tones will not be
printed from a single negative unless multiple inks are used. As
concerning the printer, I keep coming back to the issue of which inks
are going to have the appropriate transmission characteristics for the
process I am printing.
Another suspicion that has developed is that each of the colors selected
should be within the gamut of the printer or its driver may try to
adjust and change them or just print them as the closest color within
gamut (which could be the same as for an already used tone value). This
should be kept in mind when setting up the color table.
--
Jeffrey D. Mathias
http://home.att.net/~jeffrey.d.mathias/