Scaling of bitmaps different in Inkscape and browsers

[texnic]

I've imported a PDF page with a bitmap figure, ungrouped it and deleted everything except for the figure and the caption. I've also applied some horizontal scaling to it. Then I added a few objects on top of it with Inkscape (actually Matlab > plot2svg > edit in Inkscape).

The saved SVG doesn't render the same way in Inkscape and in web-browsers: the underlying bitmap is not matching the stuff I drew on top of it in the browsers. (In the attached file, the horizontal widths of the b/w and colour subplots should be equal.) The PNG export works fine (things coincide).

Inkscape 0.48.2 r9819, Windows 7 Pro 64 bit.
Google Chrome 19.0.1084.46 m
Internet Explorer 9.0.8112.16421

[su_v (suv-lp)]

The embedded bitmap image (width = height = 1) which renders in a different size is actually used as (inverted) mask on a rectangle within a scaled group.

AFAICT a duplicate of (or related to)
Bug #461467 in Inkscape: “Image scale saved incorrectly”
<https://bugs.launchpad.net/inkscape/+bug/461467>

See also:
Bug #616717 “Resized bitmap images are rendered differently by Firefox or Batik ('preserveAspectRatio' attribute not set)”
<https://bugs.launchpad.net/inkscape/+bug/616717>
Bug #924377 “wrong default value for image preserveAspectRatio”
<https://bugs.launchpad.net/inkscape/+bug/924377>

[su_v (suv-lp)]

Adding
         preserveAspectRatio="none"
to the bitmap image in the <mask> element fixes the reported issue.

Linking as duplicate to bug #616717.