[tex-live] Is this a real PNG/pdfTeX error in TL2004? Or Mac OSXonly?

[Hans Hagen]

Sebastian Rahtz wrote:
> Surely PNG to PDF is not a transformation, exactly? just a repackaging,
> as the PDF format understands PNG sort of natively? or am I entirely
> mis-remembering?

yes (it's a kind of repackaging) and no (transformation needed in most cases)

there are a couple of axis involved when including bitmaps: compression, 
colorspace, depth, predictors; so, it's probably best to talk of png, tiff, jpeg 
compression and not so much in terms of 'embedding as png' (it's mostly png 
predictors that pdf thinks of); so, during embedding some kind of conversion can 
take place, although sometimes the bitstream can be passed on (used) directly.

png does not need that much handling, tiff is worse: of the hundreds of variants 
only a few are supported (the fax ones for instance, high b/w compression, 
probably there for this 'use pdf as container for scanned documents' game)

concerning png inclusion: the most prominent problem there is in transparant 
(and masking) applications, since then it has to be hooked into the pdftex 
resource (dict) handling and such; that kind of interplay will always be needed 
when embedding graphics

concerning inclusion: so far we could get away with the fuzzy grouping stuff 
(probably something closely related to editing in illustrator)

Hans



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