Related tdf#135561: read ase palette with Lab colormodel

I took example on colorConversions.js from avisek, see
https://gist.github.com/avisek/eadfbe7a7a169b1001a2d3affc21052e

2 steps: convert Lab to XYZ, then XYZ to RGB

credit Avisek Das and István Ujj-Mészáros

Change-Id: I3a80259b6de1aca7fe3c308d9024e9b9f2a5a425
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/171729
Reviewed-by: Michael Meeks <michael.meeks@collabora.com>
Reviewed-by: Julien Nabet <serval2412@yahoo.fr>
Tested-by: Jenkins

1 files changed, 102 insertions, 7 deletions

diff --git a/svx/source/tbxctrls/Palette.cxx b/svx/source/tbxctrls/Palette.cxx
index 8f78c0c2bc45..29158cbfcac8 100644
--- a/svx/source/tbxctrls/Palette.cxx
+++ b/svx/source/tbxctrls/Palette.cxx
@@ -78,6 +78,102 @@ static void lcl_CMYKtoRGB( float fCyan, float fMagenta, float fYellow, float fKe
     dB = std::clamp( 1.0 - fYellow, 0.0, 1.0 );
 }
 
+// This function based on code under ALv2 - Copyright 2013 István Ujj-Mészáros
+// credit Avisek Das and István Ujj-Mészáros
+static void lcl_XYZtoRGB( float fX, float fY, float fZ, float& dR, float& dG, float& dB)
+{
+    // Observer = 2°, Illuminant = D65
+    fX = fX / 100;
+    fY = fY / 100;
+    fZ = fZ / 100;
+
+    // X from 0 to 95.047
+    dR = fX * 3.2406 + fY * -1.5372 + fZ * -0.4986;
+    // Y from 0 to 100.000
+    dG = fX * -0.9689 + fY * 1.8758 + fZ * 0.0415;
+    // Z from 0 to 108.883
+    dB = fX * 0.0557 + fY * -0.2040 + fZ * 1.0570;
+
+    if (dR > 0.0031308)
+    {
+        dR = 1.055 * (std::pow(dR, 0.41666667)) - 0.055;
+    }
+    else
+    {
+        dR = 12.92 * dR;
+    }
+
+    if (dG > 0.0031308)
+    {
+        dG = 1.055 * (std::pow(dG, 0.41666667)) - 0.055;
+    }
+    else
+    {
+        dG = 12.92 * dG;
+    }
+
+    if (dB > 0.0031308)
+    {
+        dB = 1.055 * (std::pow(dB, 0.41666667)) - 0.055;
+    }
+    else
+    {
+        dB = 12.92 * dB;
+    }
+    dR *= 255;
+    dG *= 255;
+    dB *= 255;
+}
+
+// This function based on code under ALv2 - Copyright 2013 István Ujj-Mészáros
+// credit Avisek Das and István Ujj-Mészáros
+static void lcl_LABtoXYZ( float fL, float fa, float fb, float& dX, float& dY, float& dZ)
+{
+    dY = (fL + 16) / 116;
+    dX = (fa / 500) + dY;
+    dZ = dY - (fb / 200);
+
+    if (std::pow(dY, 3) > 0.008856)
+    {
+        dY = std::pow(dY, 3);
+    }
+    else
+    {
+        dY = (dY - 0.137931034) /  7.787;
+    }
+
+    if (std::pow(dX, 3) > 0.008856)
+    {
+        dX = std::pow(dX, 3);
+    }
+    else
+    {
+        dX = (dX - 0.137931034) /  7.787;
+    }
+
+    if (std::pow(dZ, 3) > 0.008856)
+    {
+        dZ = std::pow(dZ, 3);
+    }
+    else
+    {
+        dZ = (dZ - 0.137931034) /  7.787;
+    }
+
+    // Observer = 2°, Illuminant = D65
+    dX = 95.047 * dX;
+    dY = 100.000 * dY;
+    dZ = 108.883 * dZ;
+}
+
+static void lcl_LABtoRGB( float fL, float fa, float fb, float& dR, float& dG, float& dB)
+{
+    float x, y, z;
+    lcl_LABtoXYZ(fL, fa, fb, x, y, z);
+
+    lcl_XYZtoRGB(x, y, z, dR, dG, dB);
+}
+
 void PaletteASE::LoadPalette()
 {
     SvFileStream aFile(maFPath, StreamMode::READ);
@@ -153,14 +249,13 @@ void PaletteASE::LoadPalette()
             aFile.ReadFloat(nVal);
             r = g = b = nVal;
         }
-        else
+        else if (aColorModel.equalsIgnoreAsciiCase("LAB "))
         {
-            float nL = 0, nA = 0, nB = 0;
-            aFile.ReadFloat(nL);
-            aFile.ReadFloat(nA);
-            aFile.ReadFloat(nB);
-            // TODO: How to convert LAB to RGB?
-            r = g = b = 0;
+            float fL = 0, fA = 0, fB = 0;
+            aFile.ReadFloat(fL);
+            aFile.ReadFloat(fA);
+            aFile.ReadFloat(fB);
+            lcl_LABtoRGB(fL, fA, fB, r, g, b);
         }
 
         // Ignore color type