U of S | Mailing List Archive | alt-photo-process-l | Re: Custom color-separations in Photoshop?

Re: Custom color-separations in Photoshop?


I was looking into the multiple separations a while back, I cam across
this fellow whose tried out the 6 color Hexachrome route:
Though he had a tough time with the last 6th layer for some reason, it
would ruin the print?
I'm unsure about spot color, though if someone knows how it works in
Photoshop to get the accuracy of what colors you want for each
sepaaration please chime in. I presume getting the correct selection
of color via photoshop is the most important part? Then applying the
appropriate color to that selection..

My original idea using separate colors was to find out where colors
fall in the color gamut and figure out how to increase the gamut with
extra color separations. Say to use a more saturated green separation
to a forest photo.
If I were successful in producing a green separation would I then
increase the color gamut of the photograph with a specific green water
color? Is it possible to do this? I'm sure there is a way and possibly
spot colors is the way to go...

Quoting Keith Gerling <keith.gerling@gmail.com>:

That is an interesting use of the B&W app. I'll have to look into that.

The reason why my original thought about custom separations is not
feasible is that one cannot get any pure primaries - red, yellow, blue
- from a pallette that uses purple, green and orange. I'm thinking
that Hexachrome separations might be interesting. Or, use a custom POG
seperation and then use spot channels to add the primaries where

On Sun, Jan 25, 2009 at 11:22 AM, Marek Matusz
<marekmatusz@hotmail.com> wrote:
CS3 has this advanced B&W filer method tthat allows application of any color
filters to a B&W image. While I do not understand the math, or principles, I
use it occasionally to creat a spot color (say orange) negative. I wonder if
in principle it could be used to create orange/green purple negatives for

Date: Sun, 25 Jan 2009 08:16:26 -0800
From: kthayer@pacifier.com
Subject: Re: Custom color-separations in Photoshop?
To: alt-photo-process-l@usask.ca

Thanks, Alberto. After I sent that first post, it occurred to me
that maybe I'd bookmarked the page, and sure enough there it was in
my bookmarks. Anyway, I don't think anyone talking about using spot
channels to achieve Keith's goal is supposing it could be an
automatic process like default Photoshop CMYK separations; Keith is
right that Photoshop won't do that. But it is a way to use Photoshop
to get the separations of secondary colors that he wanted.

On Jan 24, 2009, at 11:54 PM, Alberto Novo wrote:

>> Oh, for heavens' sake, it was Alberto Novo. I should have
>> remembered that, sorry Alberto. Anyway, here's the page: http://
>> www.grupponamias.com/index_en.html?http://www.grupponamias.com/
>> art_101_en.html
> Never mind, Katherine. I live in a different time zone, so usually
> I can't chime in at once.
> I would add that I don't believe that my process could become an
> atomatic one, though it is possible to make a Photoshop action. The
> reason is that the colors are not primary (I like to call them
> oblique, opposed to orthogonal, because they are not complemetary,
> and they are not the resultant of a rigid rotation of the axes),
> and they vary from picture to picture because of the complexity of
> the scene and the personal choices of the operator.
> Alberto

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