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LibGfx/JPEG: Add a comment to inverse_dct_8x8()

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See here:
https://github.com/SerenityOS/serenity/issues/22739#issuecomment-1890599116

No behavior change.
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Nico Weber 2024-03-21 21:09:32 -04:00 committed by Jelle Raaijmakers
parent e1598233e1
commit 730876fda9
1 changed files with 2 additions and 0 deletions
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Userland/Libraries/LibGfx/ImageFormats/JPEGLoader.cpp
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@ -1432,6 +1432,8 @@ static void dequantize(JPEGLoadingContext& context, Vector<Macroblock>& macroblo
static void inverse_dct_8x8(i16* block_component)
{
// Does a 2-D IDCT by doing two 1-D IDCTs as described in https://unix4lyfe.org/dct/
// The 1-D DCT idea is described at https://unix4lyfe.org/dct-1d/, read aan.cc from bottom to top.
static float const m0 = 2.0f * AK::cos(1.0f / 16.0f * 2.0f * AK::Pi<float>);
static float const m1 = 2.0f * AK::cos(2.0f / 16.0f * 2.0f * AK::Pi<float>);
static float const m3 = 2.0f * AK::cos(2.0f / 16.0f * 2.0f * AK::Pi<float>);