I found that evince is producing distorted pictures, slight problems when displaying an image.
The authors of evince were able to reproduce the problem and asked me to file the bug against poppler/cairo.
I am preparing pictures for a given screen size to fit in exactly
without rescaling, e.g. to fit into a 1024x768 screen. I therefore
generate a PDF document with the same aspect and paste pictures into to
fully expand to either width or height (depending on aspect).
While in principle evince does what I expect, you'll find little
distortions when comparing the picture with what evince displays
E.g. compare the details at the car or the cables in to top right
you'll find a visible loss of image quality both on larger screens
where both need to be rescaled as on screen with the exact height
of 768 pixels.
Screendump with distortions (look at the cables or the car):
I've tested it again and it works, you can try with the images demo in poppler-glib-demo program. I think the problem is that in evince 100% zoom usually requires rescaling, because screen dpi is taken into account. With the images demo you can see how the image is rendered at 1x without rescaling.