[texhax] includegraphics and image scaling

[Heiko Oberdiek]

On Fri, Dec 10, 2010 at 03:10:05PM -0500, Peter Davis wrote:

> Thank you, Heiko.  I agree that having both JFIF and EXIF data is
> over-specifying the information, and creates opportunities for such
> inconsistencies.  In fact, files with such inconsistencies are *very*
> common.  I've run into this situation, and had to code around it, many times
> over the years.
> 
> There should be some consensus on which overrides which in cases where the
> image is inconsistent.

I consider it as a bug of the application that creates the image file.
Why should one case more "bug free" than the other?

> It seems that much of the more widely used software
> (Photoshop, InDesign, Windows, pdfTeX, the IJG JPEG library, etc.) use the
> JFIF data, while ImageMagick and XeTeX use the EXIF data.

JFIF data are very easy to parse, but very few information is provided.
EXIF data needs more effort for parsing, but can provide a variety
of information. File formats with redundancy involved have the risks
of inconsistency. Fix the inconsistencies and the file reading
applications are happy.

Yours sincerely
  Heiko Oberdiek