Created attachment 122019 [details] pdf file which demonstrates the problem SUMMARY Slackware Linux, current, kde 4.14.38 When using okular to display pdf files created with gnuplot (pm3d map) hash appears over the plot areas (and colorbox). No hash (almost) when using xpdf, older version of okular (slackware 14.2, kde 4.14.32) pdftopng removes hashes... STEPS TO REPRODUCE 1. create pdf using gnuplot, cairolatex, pm3d map z.plt: set terminal cairolatex pdf standalone size 12cm,12cm set output "z.tex" A(x,y) = x**2+y**2 < 1 ? exp(-x**2-y**2) : NaN set xrange [-2:2] set yrange [-2:2] set isosamples 300 set pm3d map splot A(x,y) -- $ gnuplot z.plt $ pdflatex z $ okular z.pdf OBSERVED RESULT hash lines over the image and colorbox EXPECTED RESULT smooth color image SOFTWARE/OS VERSIONS Windows: macOS: Linux/KDE Plasma: Slackware current (14.2+), kde 4.14.38 (available in About System) KDE Plasma Version: KDE Frameworks Version: Qt Version: 4.8.7 ADDITIONAL INFORMATION
Created attachment 122023 [details] Hatches on the plot (Okular and Chromium) Okular 1.8.70 (poppler 0.80) - right, Chromium - left (no hatches). qpdfview shows the same hatches so this might be a poppler issue (if it is an issue).
Okular setting "graphics smoothing" removes the effect ... still,looks like it's a bug.
Not an okular bug, and not a poppler bug either. Rendering lines is terribly hard, you can't always do it like the person that created the PDF wanted because people expect different things, sadly that's why the setting exists.