Stefan Roellin wrote: >Hi, > >I have submitted a patch which (slightly) improves the quality of the print >plugin (see Bug #387604). The problem basically was that Postscript can't >cope with transparency. In contrast, PDF is able to do so. > >The current implementation/patch now has a disadvantage: if you print to a >postscript target, the image has to be exported TWICE: once for the 'print >preview widget' (with alpha) and once for the postscript target (without >alpha). This is certainly not optimal regarding memory consumption. > >So the question is, whether this is a real problem or not. > > > For me, it is a serious problem. I work in the print industry, typically creating PostScript drivers. The PS output is quite good quality, and every conversion generally suffers serious quality issues. Gimp is one of the best tools available for UNIX side PostScript. Photoshop and some other tools, despite being Adobe products, tend to break standards compliant high end print systems (most of those products work great so long as you don't mix them with other people's products, then they suck...gimp PS works flawlessly with all of the certified systems). As soon as you start making PDF-to-PostScript conversions or PostScript-to-PDF-to-PostScript, the output is hopeless. Don't do it.
>If yes, a solution could be to not distinguish between a Postscript and a >PDF target (i.e. to embed only opaque images into a PDF despite the fact >that PDF can handle images with alpha values). In this case, we only have to >export the image at most once. > > PDF is pretty much a subset of PostScript with a hierarchy, at least in the basic early versions. When you start getting into more recent versions, it diverges, but still contains mainly a subset of PostScript operators for the vector and bitmap part of it. If you wanted support for PDF, you'd be better off making both PS and PDF output options. It'd be nice to have direct PDF output, but this is a document interchange format, and NOT a print format. There is no reason to not add dual output format, but there is an extrordinary loss of quality by removing direct PostScript output (FYI, I must often slice and dice the raw PostScript, and gimp has the most sane version among the common tools). FYI, a proper conversion tool can convert from PS to PDF without loss, but virtually all tools have issues, mainly when converting vector to bitmap, or using lossy compression without an option to say no to it. If anyone really felt the need to improve print options, my own feeling from coding for the print industry is that more options on compression formats and font embedding (perhaps not relevant for gimp) would be appropriate. D. Stimits, stimits AT comcast DOT net _______________________________________________ Gimp-developer mailing list Gimp-developer@lists.XCF.Berkeley.EDU https://lists.XCF.Berkeley.EDU/mailman/listinfo/gimp-developer