From bdd2404453d1ac9093568c94b89ea2d6ea93d750 Mon Sep 17 00:00:00 2001
From: Nico Weber <thakis@chromium.org>
Date: Tue, 31 Oct 2023 21:03:19 -0400
Subject: [PATCH] LibPDF: Ignore input whitepoint in convert_to_d65()

CalRGBColorSpace::color() converts into a flat xyz space,
which already takes input whitepoint into account.

It shouldn't be taken into account again when converting from
the flat color space to D65.
---
 Userland/Libraries/LibPDF/ColorSpace.cpp | 10 +++-------
 1 file changed, 3 insertions(+), 7 deletions(-)

diff --git a/Userland/Libraries/LibPDF/ColorSpace.cpp b/Userland/Libraries/LibPDF/ColorSpace.cpp
index 6db02ac7e2..3d18e281ff 100644
--- a/Userland/Libraries/LibPDF/ColorSpace.cpp
+++ b/Userland/Libraries/LibPDF/ColorSpace.cpp
@@ -293,17 +293,13 @@ constexpr Array<float, 3> scale_black_point(Array<float, 3> blackpoint, Array<fl
 }
 
 // https://en.wikipedia.org/wiki/Illuminant_D65
-constexpr Array<float, 3> convert_to_d65(Array<float, 3> whitepoint, Array<float, 3> xyz)
+constexpr Array<float, 3> convert_to_d65(Array<float, 3> xyz)
 {
     constexpr float d65x = 0.95047f;
     constexpr float d65y = 1.0f;
     constexpr float d65z = 1.08883f;
 
-    return {
-        (xyz[0] * d65x) / whitepoint[0],
-        (xyz[1] * d65y) / whitepoint[1],
-        (xyz[2] * d65z) / whitepoint[2],
-    };
+    return { xyz[0] * d65x, xyz[1] * d65y, xyz[2] * d65z };
 }
 
 // https://en.wikipedia.org/wiki/SRGB
@@ -343,7 +339,7 @@ PDFErrorOr<Color> CalRGBColorSpace::color(ReadonlySpan<Value> arguments) const
 
     auto flattened_xyz = flatten_and_normalize_whitepoint(m_whitepoint, { x, y, z });
     auto scaled_black_point_xyz = scale_black_point(m_blackpoint, flattened_xyz);
-    auto d65_normalized = convert_to_d65(m_whitepoint, scaled_black_point_xyz);
+    auto d65_normalized = convert_to_d65(scaled_black_point_xyz);
     auto srgb = convert_to_srgb(d65_normalized);
 
     auto red = static_cast<u8>(srgb[0] * 255.0f);