Created attachment 163765 [details] pngquant-ed reproduction file SUMMARY *** Fractional zoom causes 8-bit PNG to produce black pixel artifacts. *** STEPS TO REPRODUCE 1. Open the attached PNG in Gwenview 2. Use scroll wheel zoom OBSERVED RESULT Fractional zoom values are scaled without artifacting EXPECTED RESULT Black pixel artifacts. WITHOUT artifacts are those zoom values: 100%, 400%, 800%, 1600% SOFTWARE/OS VERSIONS Linux/KDE Plasma: (available in About System) KDE Plasma Version: 5.27.9 KDE Frameworks Version: 5.112.0 Qt Version: 5.15.11 Gwenview: 23.08.3 on Manjaro and 22.04.1 on Fedora ELRepo ADDITIONAL INFORMATION I am not sure if it's paletted, probably yes. I got that image after optimization with PNGaunglet. `file` output: "PNG image data, 1307 x 304, 8-bit colormap, non-interlaced" The effect seems to be stronger on 23.08.3 than on 22.04.1 I could reproduce this effect after running a similar image through `pngquant --nofs path/to.png` Other programs that work correctly: gThumb, qView, KDE's Pix, Krita, GIMP, IrfanView, Firefox
Thank you for the bug report. Unfortunately we were not able to get to it yet. Can we ask you to please check if this is still an issue with Gwenview 25.08.0?
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I am going to mark this as fixed. I cannot reproduce this anymore, it works now: Gwenview: 25.04.3 KDE Frameworks: 6.17.0 Qt: Using 6.9.1 and built against 6.9.1 Manjaro Linux (Xcb) Build ABI: x86_64-little_endian-lp64 Kernel: linux 6.15.9-2-MANJARO