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LibPDF: Convert LAB values to bytes differently

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Gfx::ICC::Profile's current API takes bytes, so we need to do some
contortions for LAB values to go through.

This will probably become nicer once we implement all the backward
transforms in Gfx::ICC::Profile, but for now let's hack it in
on the LibPDF side.

Makes colors in 0000651.pdf looks good, especially on pages 1 and 7-12.
This commit is contained in:
Nico Weber 2023-11-25 22:06:44 -05:00 • committed by Tim Flynn
parent 715d0bacdb
commit 4cb0593daf
1 changed files with 14 additions and 2 deletions
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16
Userland/Libraries/LibPDF/ColorSpace.cpp
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@ -499,9 +499,21 @@ PDFErrorOr<Color> ICCBasedColorSpace::color(ReadonlySpan<Value> arguments) const
s_srgb_profile = TRY(Gfx::ICC::sRGB()); s_srgb_profile = TRY(Gfx::ICC::sRGB());
Vector<u8> bytes; Vector<u8> bytes;
for (auto const& arg : arguments) { for (size_t i = 0; i < arguments.size(); ++i) {
auto const& arg = arguments[i];
VERIFY(arg.has_number()); VERIFY(arg.has_number());
bytes.append(static_cast<u8>(arg.to_float() * 255.0f)); float number = arg.to_float();
if (m_profile->data_color_space() == Gfx::ICC::ColorSpace::CIELAB) {
// CIELAB channels go from 0..100 and -128..127 instead of from 0..1.
// FIXME: We should probably have an API on Gfx::ICC::Profile that takes floats instead of bytes and that does this internally instead.
if (i == 0)
number /= 100.0f;
else
number = (number + 128.0f) / 255.0f;
}
bytes.append(static_cast<u8>(number * 255.0f));
} }
auto pcs = TRY(m_profile->to_pcs(bytes)); auto pcs = TRY(m_profile->to_pcs(bytes));