Fix bug in LRGB <-> XYZ conversion

Colors need to be clipped after the conversion.

Also update license and fix slight rounding issues with weights.

1 files changed, 17 insertions, 23 deletions

diff --git a/oklab.cginc b/oklab.cginc
index f6b788c..ca796de 100644
--- a/oklab.cginc
+++ b/oklab.cginc
@@ -1,7 +1,7 @@
 /*
  * MIT License
  *
- * Copyright (c) 2023 yum_food
+ * Copyright (c) 2023-2024 yum_food
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to
@@ -38,9 +38,8 @@ float3 LRGBtoXYZ(float3 c) {
   float3x3 rgb_to_xyz = float3x3(
       0.4124, 0.3576, 0.1805,
       0.2126, 0.7152, 0.0722,
-      0.0193, 0.1192, 0.9505
-      );
-  return mul(rgb_to_xyz, c);
+      0.0193, 0.1192, 0.9505);
+  return saturate(mul(rgb_to_xyz, c));
 }
 
 // Weights: https://en.wikipedia.org/wiki/SRGB
@@ -48,23 +47,20 @@ float3 XYZtoLRGB(float3 c) {
   float3x3 xyz_to_rgb = float3x3(
       3.24062548, -1.53720797, -0.4986286,
       -0.96893071,  1.87575606,  0.04151752,
-      0.05571012, -0.20402105,  1.05699594
-      );
-  return mul(xyz_to_rgb, c);
+      0.05571012, -0.20402105,  1.05699594);
+  return saturate(mul(xyz_to_rgb, c));
 }
 
 // Source: https://bottosson.github.io/posts/oklab/
 float3 XYZtoOKLAB(float3 c) {
   float3x3 m1 = float3x3(
-      0.8189, 0.3618, -0.1288,
-      0.0329, 0.9293, 0.0361,
-      0.0482, 0.2643, 0.6338
-      );
+      0.8189330101, 0.3618667424, -0.1288597137,
+      0.0329845436, 0.9293118715, 0.0361456387,
+      0.0482003018, 0.2643662691, 0.6338517070);
   float3x3 m2 = float3x3(
-      0.2104, 0.7936, -0.0040,
-      1.9779, -2.4285, 0.4505,
-      0.0259, 0.7827, -0.8086
-      );
+      0.2104542553, 0.7936177850, -0.0040720468,
+      1.9779984951, -2.4285922050, 0.4505937099,
+      0.0259040371, 0.7827717662, -0.8086757660);
   c = mul(m1, c);
   c = pow(c, 0.33333333333);
   return mul(m2, c);
@@ -73,15 +69,13 @@ float3 XYZtoOKLAB(float3 c) {
 // Source: https://bottosson.github.io/posts/oklab/
 float3 OKLABtoXYZ(float3 c) {
   float3x3 m1i = float3x3(
-      1.22700842, -0.5576564 ,  0.28111404,
-      -0.04047048,  1.11219073, -0.07157255,
-      -0.07643651, -0.42138367,  1.58625265
-      );
+       1.22701385, -0.55779998,  0.28125615,
+      -0.04058018,  1.11225687, -0.07167668,
+      -0.07638128, -0.42148198,  1.58616322);
   float3x3 m2i = float3x3(
-      1.00003964,  0.39638005,  0.21589049,
-      0.99998945, -0.10553958, -0.06374665,
-      0.99999105, -0.08946276, -1.291495
-      );
+      1.00000000,  0.39633779,  0.21580376,
+      1.00000001, -0.10556134, -0.06385417,
+      1.00000005, -0.08948418, -1.29148554);
   c = mul(m2i, c);
   c = pow(c, 3);
   return mul(m1i, c);