LibGfx/JPEG: Add a comment to inverse_dct_8x8()

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

No behavior change.
This commit is contained in:
Nico Weber 2024-03-21 21:09:32 -04:00 committed by Jelle Raaijmakers
parent e1598233e1
commit 730876fda9
Notes: sideshowbarker 2024-07-17 14:36:19 +09:00

View File

@ -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>);