[comp.lang.postscript] color separations?

reid@wrl.dec.com (Brian Reid) (09/11/90)

I have some color PostScript files, and I would like to make 4-way color
separations on a black-and-white PostScript printer. I'm sure I can figure
out how to do this by thrashing around with the "setcolortransfer" and
"setblackgeneration" operators, but if somebody else has already figured this
out I would be very grateful if you could tell me the tricks.

Brian Reid
reid@decwrl.dec.com

orthlieb@adobe.COM (Carl Orthlieb) (09/11/90)

In article <1990Sep10.190354.19545@wrl.dec.com> reid@wrl.dec.com (Brian Reid) writes:
>
>I have some color PostScript files, and I would like to make 4-way color
>separations on a black-and-white PostScript printer. I'm sure I can figure
>out how to do this by thrashing around with the "setcolortransfer" and
>"setblackgeneration" operators, but if somebody else has already figured this
>out I would be very grateful if you could tell me the tricks.

Brian, these operators have been defined in the Documents/colorsep.ps
proposal on our server.  They're not in the document itself, but rather
they are in the PostScript code that images the document. These operators
were defined and used to create the examples in the document.

With the advent of Level II and other changes, we didn't feel that it was
appropriate to make these definitions available in a formal sense. They
may change in the future.  When we have got a solid definition for these
things, we'll make them available properly.

Carl 8-)
 

reid@wrl.dec.com (Brian Reid) (09/12/90)

In article <6390@adobe.UUCP> orthlieb@adobe.UUCP (Carl Orthlieb) writes:
>With the advent of Level II and other changes, we didn't feel that it was
>appropriate to make these definitions available in a formal sense. They
>may change in the future.  When we have got a solid definition for these
>things, we'll make them available properly.

What a bunch of baloney. When Adobe is good and ready they will tell us
peasants how to do this. Feh. 

I got my hands on a separation that was produced by the Adobe Separator, and
was able to reverse-engineer it. It's actually one of the best-quality pieces
of PostScript code I have ever seen, and was very easy to understand and to
modify. Basically, the knowledge that it was at all possible, and one
example, was enough for me to solve my problem. Of course, I just wanted to
separate against standard process colors, and I didn't need any fancy stuff,
and I didn't need spot color, and my application is not very sensitive to
incorrect halftoning, so it went quite well.

While I can understand Adobe's position about not wanting to release code
that is not perfect, especially given the vile dreck bad PostScript that so
many applications generate, at some point enough becomes enough and you
should just let people have what's there so we can get our work done.

My kudos to whomever wrote the "Adobe_separation" ProcSet. It's a
masterpiece. I know I'm somewhat of a stranger to this newsgroup, but, trust
me, I'm no stranger to PostScript and my kudos with respect to code quality
don't come easily.

Brian