[pdftex] graphic{s,x} PNG + pdflatex bug

[Thanh Han The]

On 5/7/10, George N. White III <gnwiii at gmail.com> wrote:
> On Thu, May 6, 2010 at 2:41 PM, Martin Heller <mr_heller at yahoo.dk> wrote:
>
> > On 2010-05-06 16:31, Nico Schlömer wrote:
>  >>
>  >> Hi all,
>  >>
>  >> I experienced a weird bug using \includegraphics of the graphicx
>  >> package with pdflatex 1.40.10.
>  >>
>  >> I try to load the attached PNG file, and unlike with other PNG files,
>  >> pdflatex would just bail out with
>  >>
>  >> ==================== *snip* ====================
>  >> [...]
>  >> [Loading MPS to PDF converter (version 2006.09.02).]
>  >> )
>  >> ! Dimension too large.
>  >> <argument>  \wd \@tempboxa
>  >> l.7 \includegraphics{img1.png}
>  >> ?
>  >> ==================== *snap* ====================
>  >>
>  >> David Carlisle, maintainer of graphicx, suggests that may be a bug in
>  >> pdflatex -- What do you reckon?
>
>
> Actually, the "! Dimension too large" is accurate here.
>
>
>  > Your image has a rather odd resolution.
>  >
>  > Image: img1.png
>  >  Format: PNG (Portable Network Graphics)
>  >  Class: DirectClass
>  >  Geometry: 250x250+0+0
>  >  Resolution: 0.39x0.39
>  >  Print size: 641.026x641.026
>  >  Units: PixelsPerInch
>  >
>  > So your png is 250/0.39 = 641.026 in wide.
>  >
>  > That is 46153 pt which is larger than \maxdimen. Change the resolution and
>  > your image works fine with \includegraphics.
>
>
> Saving with Photoshop doesn't affect the above values, but does add
>  PNG VirtualPage Tags (vpAg in pngcheck):
>
>  Index   Tag Name
>  0       VirtualImageWidth
>  1       VirtualImageHeight
>  2       VirtualPageUnits
>
>  Since the Photoshopped image works, it seems that pdftex uses
>  the vpAg values when present in preference to the pixel sizes.

pdftex uses libpng to read png files and relies on what libpng
returns.

Thanh