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

George N. White III aa056 at chebucto.ns.ca
Fri Nov 19 18:21:06 CET 2004

On Thu, 18 Nov 2004, 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?

There are many shades of "understanding".  pdftexdir/writepng.c uses 
libpng (image.h pulls in png.h) to parse the PNG file for the color model 
and get the image data, which are uncompressed and then recompressed, so 
zlib is used via libpng.  Not all png files are supported (does PDF handle 
16-bit images?).  TeX users are better off saving their images as PDF
directly and bypassing the PNG format.  In a perfiect world PNG files
would be 1-page PDF's that contain only images -- maybe this will
be the turbo-PNG format.

George N. White III  <aa056 at chebucto.ns.ca>
   Head of St. Margarets Bay, Nova Scotia, Canada

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