[XeTeX] Size of JPEG graphics

[Bruno Voisin]

Hello,

I have just been faced with a strange behaviour of XeTeX compared with 
pdfTeX, and it took some time to reduce the observed behaviour to a 
simple fact: for a JPEG file that I created using Adobe Illustrator 
(opening an EPS file in Illustrator, modifying it, and saving the 
result as a JPEG file), and included in a TeX file, the size of the 
JPEG image in the PDF output is different depending on whether pdfTeX 
or XeTeX is used. (By size here I mean the size in centimeters (or 
inches!) on the page, not the size of the file.)

This happens with either LaTeX, including the file, called 
perspdip.jpg, with:

	\includegraphics{perspdip.jpg}

and appropriate \usepackage[pdftex]{graphicx} or 
\usepackage[xetex]{graphicx}, or with plain TeX, including the file for 
pdfTeX with:

	\pdfximage{perspdip.jpg}\pdfrefximage\pdflastximage

and for XeTeX with

	\XeTeXpicfile "perspdip.jpg"

On second thought it's not so surprising, given (I think) pdfTeX gets 
its information on the JPEG image directly from the JPEG file whereas 
XeTeX relies on the information returned, about this file, by 
QuickTime, but is this a known fact and is there something that can be 
done about it?

This behaviour is not specific to the current (0.84) version of XeTeX, 
I had experienced it before though at the time I did not know what 
exactly was going wrong.

Bruno Voisin