Keep scalar PNG Avg/Paeth unfilters for 1-byte pixels - #950
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Whole-vector Avg/Paeth is serial for n=1, so the SIMD path was slower than Base on Gray8. Leave grayscale Avg/Paeth/AvgFirst on the scalar fallback and keep vector paths for n>=2. Co-authored-by: igor.ermolaev <igor.ermolaev@altezza.org>
ermig1979
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September 8, 2026 15:19
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Follow-up to #949.
Whole-vector Avg/Paeth unfilters are serial for
srcN == 1, so the SIMD path was slower than Base on Gray8 (~7.5 msvs~4.3 msinImageLoadFromMemoryAutoTest).This drops the
n=1Avg/Paeth/AvgFirst cases so grayscale uses the scalar fallback. Vector paths forn>=2(RGB/RGBA and 16-bit) stay as in #949.After this change, AutoTest Gray8 is
4.182 ms(Sse41) vs4.278 ms(Base). Color-format speedups from #949 are unchanged.