patwood@unirot.UUCP.UUCP (04/04/87)
Since there are few people who have actually seen an Interpress and/or DDL printer, it's hard for anyone to say anything that isn't based on some manufacturer's claim or second-hand knowledge. That said, now I'll give all of you the benefit of my second-hand knowledge and manufacturer's claims (;-): Xerox says that Interpress is designed for speed and is faster than PostScript. Considering that the only version of Interpress that's available now doesn't do graphics, only text and scanned images (no vector graphics, clipping, or rotation of text), I can see why it's fast. Xerox also says that Interpress is "a printing architecture that clearly distinguishes the process belong on the printing domain from those in the document creation domain. By placing many decisions on the computer's side, Interpress increses printer efficiency. In addition, by requiring greater structure in a master, Interpress limits the application from creating a master that would consume unnecessary amounts of processing time at the printer." Read that any way you want, to me it means that Interpress gains speed by giving up some flexibility. Interpress does support printing over Xerox' XNS network. The document that Xerox sent me was printed on a Xerox 8044 printer over XNS. The font is a san-serif; it looks nice, has good letterspacing and overall is more than acceptable. I'm posting a message about DDL that Geof Cooper at Imagen originally posted to the net last September. I can't vouch for the validity of any of the statements in that posting; however, I can say that there is one inaccuracy: >DDL allows for user selection of both linear and nonlinear scaling of fonts. >It is the only description language with this capability. PostScript also allows for nonlinear scaling of fonts (see "Tips and Tricks", The PostScript Language Journal, 1Q87, pp. 37-40). I think that DDL's most important feature is its ability to define graphical objects that are precompiled by the interpreter. If this also means that the object is cached as a bitmap, then some applications will run much faster under DDL compared to PostScript if they use the same graphic many times. (Don't write back to me telling me about the PostScript font cache. It does effectively the same thing; however, you have little control over what goes into it except the maximum size of the character cached. With a large enough font cache, you could, in fact, cache graphics; however, that's not quite the same thing.) If this allows caching of halftones (which can't be done in PostScript, and I'm not sure if you'd really want to do it anyway, since you want your halftone screens to line up...) then certain applications that use halftones over will run faster with DDL. (You reading this Dave Y?) Pat Wood Editor, The PostScript Language Journal [[Editor's note: I have decided not to resend the old list message from Geof Cooper because of its size. I think that understanding this message and the current discussion does not depend on this older message. --Rick ]]