mpv-player
Correct-downscaling causes ewa_lanczossharp to introduce a half-pixel shift when downsampling sometimes
Important Information
- mpv version: mpv v0.37.0-234-g57d68262
- Platform and Version: Windows 11 Pro 22H2
- Source of the mpv binary: Shinchiro
- If known which version of mpv introduced the problem: No idea
- GPU model, driver and version: 6600XT Adrenalin 24.1.1
- Possible screenshot or video of visual glitches: All below
Reproduction steps
magick convert rei.png -filter lanczossharp -distort resize 75% im_ewa_lanczossharp.png
mpv --no-config --vo=gpu-next --gpu-api=vulkan --no-hidpi-window-scale --pause=yes --screenshot-format=png --deband=no --dither-depth=no --screenshot-high-bit-depth=no --dscale=ewa_lanczossharp --linear-downscaling=no --window-scale=0.75 rei.png
mpv --no-config --vo=gpu-next --gpu-api=vulkan --no-hidpi-window-scale --pause=yes --screenshot-format=png --deband=no --dither-depth=no --screenshot-high-bit-depth=no --dscale=ewa_lanczossharp --linear-downscaling=no --window-scale=0.75 --correct-downscaling=no rei.png
Expected behavior
mpv's output should probably roughly match whatever ImageMagick is doing.
Actual behavior
mpv's output with correct-downscaling turned on appears to have a half-pixel shift towards the top-left corner (rounding issue somewhere?). Screenshot with it turned off also provided to show that there's no shift in this case, so the problem seems related to turning it on. Filters with integer supports seem fine as well.
