Created attachment 104505 [details] Tar of some examples and the source PDF I use Okular to read scores a lot, but have noticed a couple of problems which cause misreadings. 1) Note heads have ambiguous placements as shown in '100 percent.png' and 'step up.png'. If they aren't either on the line or in the middle of two lines, they are very confusing to read. 2) When zoomed out, the lines have uneven distances, making some patterns hard to read. Maybe this could be sorted with dithering? This seems to be a problem in PDFs exported from multiple notation programs. Attached is a MuseScore example. Google document viewer seems to handle scores better but not perfectly.
Created attachment 116369 [details] screenshots of the same places as before
With okular 1.6.70 and KDE Frameworks 5.53.0, Qt 5.11.2 and xcb I get render shown in the screenshots.
It can also depend on PDF backend configuration. It is worth to try all three options of rendering to choose the one which works the best for you. https://docs.kde.org/trunk5/en/kdegraphics/okular/config-pdf.html
Created attachment 116410 [details] .tar.gz of some KolourPaint-scaled .pngs for comparison The new screenshots do look different, but the problems are still there to varying extents. I can't try out other back-ends or make detailed examples just yet as I don't have a properly functional desktop system installed right now, but will try to do that soon. ‘100 percent_fixed.png’ is no longer ambiguous, but all the notes look a little bit too high up on the staff. Something that could be adjusted to, but it's still not quite right. ‘line spacing_fixed.png’ has much better spacing, but the first ledger line looks very odd due to the double thickness. In ‘step up_fixed.png’, the placement has become even more ambiguous — 3 out of 5 notes would now be misread due to being shown a step higher. I've screenshotted the file as displayed at 400% zoom, and used KolourPaint to smooth scale it to the sizes in the examples. This scaling may be inaccurate as I'm on an older version of Okular. This type of scaling results in more readable scores, but then the dithered lines look very odd. Could I suggest marking this as unresolved? I'll try to get some proper examples posted soon.
Created attachment 116412 [details] As another reference. The same pdf as rendered by chrome pdfjs viewer
Oh, I can see now that the problem is still there (two different notes on the same vertical space), specially when the zoom is lower than 100% (I didn't saw it last time, I need new glasses).