[texhax] includegraphics and image scaling

[Heiko Oberdiek]

On Thu, Dec 09, 2010 at 06:39:03PM -0500, Peter Davis wrote:

> On Thu, Dec 9, 2010 at 6:13 PM, Peter Davis <pfd at pfdstudio.com> wrote:
> 
> >
> >
> >> I've run into this before ... where different tools report different
> >> resolutions for JPEG files.  If memory serves, ImageMagick always reported
> >> 72dpi, whereas the IJG JPEG Library reported something else.  I think this
> >> is the result of multiple file formats with potentially inconsistent fields.

Maybe. However, the EXIF header of your example also shows 72dpi.

> > Interestingly, Adobe Photoshop CS5 and Adobe InDesign CS5 report the image
> > resolution as 96ppi.
> >
> > I'm using XeTeX (xelatex).  Is that using ImageMagick internally to get the
> > resolution?

AFAIK, no, but maybe the same library might be used.

> Thanks, Martin, for the tip about jhead.  I was not familiar with that tool.
>  That appears to agree with Adobe, Windows, etc:
> 
> C:\Users\peterd\images>jhead -v Chrysanthemum.jpg
> JFIF SOI marker: Units: 1 (dots per inch)  X-density=96 Y-density=96

Do you have an example image that can be analyzed?

What's the result of:

\sbox0{\includegraphics{Chrysanthemum.jpg}}
\show\wd0
\show\ht0

Yours sincerely
  Heiko Oberdiek