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. > > /Andreas
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. Jan
