vqa: fix cinematic comparison tool — _read_png_rgb PNG filter handling - #230
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…NG filters The _read_png_rgb function in scripts/cinematic-compare.py read only the first bpp bytes of each row correctly. For filter types 3 (Average) and 4 (Paeth), it skipped the first pixel, producing corrupted pixel data that made the VQA decoder look like it was failing (p99=244 vs ground truth). All 8 cinematic VQAs now pass with p99=0. Also fixed: the function never applied Sub/Up/Average/Paeth reconstruction filters. Bytes 0-bpp were always left as literal for all filter types. Now properly handles all 5 PNG filter types.
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The
_read_png_rgbfunction inscripts/cinematic-compare.pynever applied PNG reconstruction filters (Sub/Up/Average/Paeth). For filter types 3 and 4 it also skipped the firstbppbytes per row.This caused all 8 cinematic VQA comparisons to fail with p99=244 when the decoder was actually pixel-perfect (p99=0 after fix).