> avox schrieb am Montag, 14. Mai 2007: >> jrm wrote: >>> Hi, >>> >>> This regards using png images with portions that are >>> 100% transparent. What seems to happen is that this >>> kind of transparency is respected even when exporting >>> to PDF 1.3 (as seen in acroread and kpdf), which is not >>> what I was expecting. So I'm wondering if this is >>> too good to be true, that I may be able to use this >>> kind of transparency without restriction on what PDF >>> version to use, maybe even PDF/X-3... The question is, >>> can I rely on this behaviour? >>> >>> What I guess was expecting was that since "PDF 1.3 does >>> not allow transparency" the transparent part of the png >>> would be made white, or maybe black. >> >> AFAIK PDF has supported hard masks for images from the beginning >> (that's also possible in PostScript using the imagemask operator). >> >> What is only possible since 1.4 is softmasks (alpha channel), since >> those require blending imagepixels with background pixels. >> >> I don't know if the behaviour for images with an alpha channel which >> contains only 0% and 100% values is defined, better not rely on that. >> Using an indexed palette with a special color for 'transparent' >> should >> work. > > Hi, > > Though I don't know the standard, I got my X3 PDf printed corrctly, > when using > 100% transparency in PNG and tiffs. > This always seems to work, I use this bug/feature (?) every month, > when I make > a flyer.
Hi Jan, are you using bitmaps for masking? Or rgb/grayscale images with alpha or indexed transparencies? How are the flyers printed (digiprint or ctp)? curious Jon
