Bug#454550: Here is a conflict of our interests

[Zack Weinberg]

On Thu, Feb 7, 2008 at 10:45 AM, Alexander E. Patrakov
<patrakov at gmail.com> wrote:
>  Yes, and you have described them very well. Rendering them with interpolation
>  produces clearly wrong results. However, questions stand 1) whether representing
>  such sets of rectangles with low-resolution bitmaps is valid according to the
>  PostScript and PDF specifications (hint: importing this into CorelDraw under
>  Windows gives a warning about a low-resolution bitmap), and 2) if the standard
>  does allow interpolation in this case, how widespread is this assumption of
>  non-interpolated rendering in (broken) software that creates such files.

I can't speak to point 1, but the test cases I provided were generated
by Matlab, which is very widely used; I looked for a toggle to disable
this behavior and could not find one.  If you look at the upstream
bugs that this one is forwarded to, and the bugs that those are merged
with, and so on, you will see several more people with exactly the
same sort of low-resolution bitmap generated by other scientific
software, complaining loudly about the interpolation.

Thus, whether or not this tactic fits the letter of the
specifications, I think these low-resolution bitmaps (good phrase,
btw) must be rendered uninterpolated.  Note also that this is what
every PostScript printer does.

>  In either case, your "don't interpolate on upscaling" heuristic looks good
>  enough in theory, but is not currently implementable in practice for PostScript
>  files processed via Ghostscript (because there is no such command line option
>  for Evince to pass to Ghostscript). And that's a bug in Ghostscript.

Yes, that's what I meant when I said this has to be fixed in the renderers.

zw