djk@cs.columbia.edu (David Kurlander) (11/11/89)
I have a set of color postscript drawings that need to be converted into color separations for a book. Is this an easy process? Are there programs which can do this for me, or would the local techno-sophisticated print shop be able to handle it by themselves? Any advice on how to accomplish this task would be appreciated. Thanks, David -- ---------------------------------- David Kurlander Department of Computer Science djk@cs.columbia.edu Columbia University
geof@smiley.stanford.edu (Geof Cooper) (11/12/89)
In article <443@cs.columbia.edu> djk@cs.columbia.edu (David Kurlander) writes: >I have a set of color postscript drawings that need to be converted >into color separations for a book. This is comparatively easy to do in a limited way. If you don't like the results you get, it is somewhat more complicated to tune the results to the printing process (that is what color pre-press is all about, and is essentially an unsolved problem). Obstacle #1 is that older printers do not support the PostScript color operators, like "setcmykcolor" and "colorimage". If you use either of these, you will likely have to simulate them in PostScript. Obstacle #2 is that color postscript has a built in mechanism for doing "black generation", i.e., converting a CMY signal into a CMYK signal. You may need to simulate this, too. This may not be a problem if your artwork has little saturated black in it. The technique is to replicate the postscript master three times (4 times for CMYK), with three special headers prefixed that redefine the operators "setgray", "setrgbcolor", ... etc. to set a gray level that is equal to the component you want. I.e., to generate the cyan pass from "setcmykcolor", you would do something like: /setcmykcolor { pop pop pop 0 0 0 setcmykcolor } bind def with analogous definitions of the other operators. You also want to call setscreen in the prefixed code to set different rotations for the different separations. Something like a 60 degree separation works well. I would suggest that you contact Adobe on this one. I have noticed that they have ProcSets that do essentially what you want. Perhaps they will release them. They have also come up with good setscreen values for typesetters. At the very least, the "Color PostScript Extensions" document is a must to understand how to simulate the color operators and do black generation. - Geof Cooper
woody@chinacat.Unicom.COM (Woody Baker @ Eagle Signal) (05/02/90)
In article <263DD7CE.1C19@intercon.com>, amanda@mermaid.intercon.com (Amanda Walker) writes: > > The second article was one that I found more fascinating. It described > a scheme [patent pending, unfortunately :-(] that, instead of generating Remember that when a patent is applied for and issued, it has to include enough information that anyone reasonably skilled in the art can reproduce it. A Patent gives the company the right to sue if someone else trys to make money with the patent. There is nothing to prevent you from using any patent and making the item, as long as it is for your own personaly use, and you don't transfer it, sell it or give it away. You can sell COPIES of the Patents (they are Public Domain)...If the patent is assigned to the government (Anything invented by any government employee or civil servant is automaticaly assigned to the government), you may do what you want. In that case, the government automaticaly grants a royalty free license for use by anyone. Cheers Woody > four screens at angles that minimize moire patterns, generates four screens > at the same angle but offset from each other. This is something you can > do on an imagesetter but not with traditional photographic halftones (since > you can control the registration as well). They claim it looks much better > than using rotated screens, especially on lower-resolution devices (like > 300 dpi printers, although why you'd do seps at 300 dpi is beyond me). > > -- > Amanda Walker, InterCon Systems Corporation > -- > "Y'know, you can't have, like, a light, without a dark to stick it in... > You know what I'm sayin'?" --Arlo Guthrie
henry@utzoo.uucp (Henry Spencer) (05/03/90)
In article <1208@chinacat.Unicom.COM> woody@chinacat.Unicom.COM (Woody Baker @ Eagle Signal) writes: >> a scheme [patent pending, unfortunately :-(] that, instead of generating > >... A Patent gives the company the right to sue if someone else trys to >make money with the patent. There is nothing to prevent you from using >any patent and making the item, as long as it is for your own personaly >use, and you don't transfer it, sell it or give it away... Sorry, unlike copyrights, there is **NO** "fair use" exemption for patents. A patent means you can be sued if you use the invention *in any way*. No exceptions. In reality, quiet personal use is unlikely to attract legal attention, but the possibility exists. -- If OSI is the answer, what is | Henry Spencer at U of Toronto Zoology the question?? -Rolf Nordhagen| uunet!attcan!utzoo!henry henry@zoo.toronto.edu