[Poppler-bugs] [Bug 68360] Fuzzy rendering in SplashOutputDev in latest releases

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=68360

--- Comment #10 from Charles Hyder <dr.hyder at gmail.com> ---
I've attached a screenshot of the Adobe Acrobat page display settings. You're
right, Adobe does differently depending on these settings! I've always had the
"2D graphics acceleration" setting on. With it on, the rendering proceeds as it
should (in my opinion; more on that later): smoothing the image for non-integer
scaling factors and rendering bitonal for integer scaling factors. However, if
I uncheck that box then I get an option to set "Smooth images". Amazingly, this
option controls smoothing for ALL scaling factors at once: with it on you
always get smoothing (even for 1-to-1 scale), and with it off you never get
smoothing. It's amazing, but true: my graphics card driver does better job
scaling images than does Adobe )

Another example of a piece of software that proceed in the (partly) correct
fashion (in my opinion) about this is WinDjView - smoothing for all scales
except scale=1.

Another piece of (somewhat irrelevant) information about PDF: there's the
so-called "interpolate" flag for each JPEG image in the PDF that should tell
any (respecting) PDF render to interpolate images for scales > 1 (i.e., if a
PDF page containing a 300dpi image is shown at 600% magnification; screen
resolution of 100dpi is again assumed). This flag has no effect on how the
image is encoded, only on how it should be rendered. It's rarely used by PDF
producers, however. This has no direct relevance to the question we're
discussing. Just wanted to mention in case someone finds it curious.

I would like to outline the reasons for not smoothing images at integer scale
factors next. Since I was only given a choice to either close this ticket or
move it to a feature request, and since closing it means I can't write along
these lines any further I'd have to agree to moving it to a feature request.
Shall I open a feature request or you can move this stuff over there somehow?

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