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

Re: Custom color-separations in Photoshop?

Using spot color or the use of additional colors of inks, such as the Epson 7990 does, are very different from what Keith told me he wanted to do.

On Jan 24, 2009, at 6:32:54 PM, "Michael Koch-Schulte" <mkochsch@shaw.ca> wrote:

From:"Michael Koch-Schulte" <mkochsch@shaw.ca>
Subject:Re: Custom color-separations in Photoshop?
Date:January 24, 2009 6:32:54 PM CST
No. I think you're on the right track. Damn the "experts". There is a 
reason "spot" colour exists to this day and people in the printing 
industry know why. There are colours which can't be produce by just 
three "primaries" and there are also cases when primary colours are both 
not necessary and to be avoided. For example, mixing quinacridone red 
and azo yellow will give you "an" orange but it won't be as saturated or 
intense as say a benzimida or pyrrole orange which are both produced 
independently of either red or yellow pigments. Many fine art 
reproductions use multiple plates. Giclee uses 12 inks not 3.

Keith Gerling wrote:
> Forget it. After some reflection and after mulling it over with a
> resident PS expert (thanks Mark), it is apparent that what I'm looking
> for is impossible. There is a reason they are called Primary Colors!
> I will check out the Hexachrome thread, though.
> On Sat, Jan 24, 2009 at 12:22 PM, Katharine Thayer <kthayer@pacifier.com> wrote:
>> Spot color separations?
>> No, on re-reading, I think you're talking about something more
>> sophisticated. In a fairly recent thread, someone pointed to software (not
>> Photoshop) that provides separations for two of the secondaries, I think, in
>> addition to the primaries, but I didn't see anything that generates
>> separations for all three. But that thread might be a good one to revisit.
>> Ah, I found it. The thread subject is "Gum Color Gamut & Beyond CMYK"
>> starting September 22, 2008. On re-reading, I'm not sure it contains much
>> useful information beyond the name of the application (Pantone Hexachrome)
>> that makes the five-color separations. But you might read through to see
>> for yourself.
>> Katharine
>> On Jan 24, 2009, at 9:49 AM, Keith Gerling wrote:
>>> I was wondering if there was any method in Photoshop, or with a
>>> Photoshop plugin where one could perform custom color separations.
>>> The RGB and CMYK channels are universal ways of splitting a full color
>>> image into 3 or four standard colors. Wouldn't it be possible to
>>> split an image into components of Purple, Orange and Green, for
>>> instance? It would be like turning the color wheel a notch.
>>> Conceivably, if all the color information can be conveyed in CMYK, it
>>> ought to be accurately conveyed with other color channels as well.
>>> Or am I missing something?
>>> This could provide all kinds of interesting possibilities for
>>> tri-color gum printing.