CalRGB color correction

core/src/fpdfapi/fpdf_page/fpdf_page_colors.cpp

Index: core/src/fpdfapi/fpdf_page/fpdf_page_colors.cpp
diff --git a/core/src/fpdfapi/fpdf_page/fpdf_page_colors.cpp b/core/src/fpdfapi/fpdf_page/fpdf_page_colors.cpp
index 1cd109784d76ef14d209263bf9e8e4dabeee4834..467fb63f474630093924bd4912e65dd2e666d2f7 100644
--- a/core/src/fpdfapi/fpdf_page/fpdf_page_colors.cpp
+++ b/core/src/fpdfapi/fpdf_page/fpdf_page_colors.cpp
@@ -207,56 +207,59 @@ const FX_BYTE g_sRGBSamples2[] = {
     241, 241, 242, 242, 243, 243, 244, 244, 245, 245, 246, 246, 246, 247, 247, 248,
     248, 249, 249, 250, 250, 251, 251, 251, 252, 252, 253, 253, 254, 254, 255, 255,
 };
-static void XYZ_to_sRGB(FX_FLOAT X, FX_FLOAT Y, FX_FLOAT Z, FX_FLOAT& R, FX_FLOAT& G, FX_FLOAT& B)
+
+static FX_FLOAT RGB_Conversion(FX_FLOAT colorComponent)
 {
-    FX_FLOAT R1 = 3.2410f * X - 1.5374f * Y - 0.4986f * Z;
-    FX_FLOAT G1 = -0.9692f * X + 1.8760f * Y + 0.0416f * Z;
-    FX_FLOAT B1 =  0.0556f * X - 0.2040f * Y + 1.0570f * Z;
-    if (R1 > 1) {
-        R1 = 1;
-    }
-    if (R1 < 0) {
-        R1 = 0;
-    }
-    if (G1 > 1) {
-        G1 = 1;
-    }
-    if (G1 < 0) {
-        G1 = 0;
-    }
-    if (B1 > 1) {
-        B1 = 1;
+    if (colorComponent > 1) {
+        colorComponent = 1;
     }
-    if (B1 < 0) {
-        B1 = 0;
+    if (colorComponent < 0) {
+        colorComponent = 0;
     }
-    int scale = (int)(R1 * 1023);
+    int scale = (int)(colorComponent * 1023);
     if (scale < 0) {
         scale = 0;
     }
     if (scale < 192) {
-        R = (g_sRGBSamples1[scale] / 255.0f);
-    } else {
-        R = (g_sRGBSamples2[scale / 4 - 48] / 255.0f);
-    }
-    scale = (int)(G1 * 1023);
-    if (scale < 0) {
-        scale = 0;
-    }
-    if (scale < 192) {
-        G = (g_sRGBSamples1[scale] / 255.0f);
-    } else {
-        G = (g_sRGBSamples2[scale / 4 - 48] / 255.0f);
-    }
-    scale = (int)(B1 * 1023);
-    if (scale < 0) {
-        scale = 0;
+        colorComponent = (g_sRGBSamples1[scale] / 255.0f);
     }
-    if (scale < 192) {
-        B = (g_sRGBSamples1[scale] / 255.0f);
-    } else {
-        B = (g_sRGBSamples2[scale / 4 - 48] / 255.0f);
+    else {
+        colorComponent = (g_sRGBSamples2[scale / 4 - 48] / 255.0f);
     }
+    return colorComponent;
+}
+
+static void XYZ_to_sRGB(FX_FLOAT X, FX_FLOAT Y, FX_FLOAT Z, FX_FLOAT& R, FX_FLOAT& G, FX_FLOAT& B)
+{
+    FX_FLOAT R1 = 3.2410f * X - 1.5374f * Y - 0.4986f * Z;
+    FX_FLOAT G1 = -0.9692f * X + 1.8760f * Y + 0.0416f * Z;
+    FX_FLOAT B1 =  0.0556f * X - 0.2040f * Y + 1.0570f * Z;
+
+    R = RGB_Conversion(R1);
+    G = RGB_Conversion(G1);
+    B = RGB_Conversion(B1);
+}
+
+static void XYZ_to_sRGB_WhitePoint(FX_FLOAT X, FX_FLOAT Y, FX_FLOAT Z, FX_FLOAT& R, FX_FLOAT& G, FX_FLOAT& B, FX_FLOAT Xw, FX_FLOAT Yw, FX_FLOAT Zw)
+{
+    // The following RGB_xyz is based on
+    // sRGB value {Rx,Ry}={0.64, 0.33}, {Gx,Gy}={0.30, 0.60}, {Bx,By}={0.15, 0.06}
+
+    FX_FLOAT Rx = 0.64f, Ry = 0.33f;
+    FX_FLOAT Gx = 0.30f, Gy = 0.60f;
+    FX_FLOAT Bx = 0.15f, By = 0.06f;
+    CFX_Matrix_3by3 RGB_xyz(Rx, Gx, Bx, Ry, Gy, By, 1 - Rx - Ry, 1 - Gx - Gy, 1 - Bx - By);
+    CFX_Vector_3by1 whitePoint(Xw, Yw, Zw);
+    CFX_Vector_3by1 XYZ(X, Y, Z);
+
+    CFX_Vector_3by1 RGB_Sum_XYZ = RGB_xyz.Inverse().TransformVector(whitePoint);
+    CFX_Matrix_3by3 RGB_SUM_XYZ_DIAG(RGB_Sum_XYZ.a, 0, 0, 0, RGB_Sum_XYZ.b, 0, 0, 0, RGB_Sum_XYZ.c);
+    CFX_Matrix_3by3 M = RGB_xyz.Multiply(RGB_SUM_XYZ_DIAG);
+    CFX_Vector_3by1 RGB = M.Inverse().TransformVector(XYZ);
+
+    R = RGB_Conversion(RGB.a);
+    G = RGB_Conversion(RGB.b);
+    B = RGB_Conversion(RGB.c);
 }
 class CPDF_CalGray : public CPDF_ColorSpace
 {
@@ -386,7 +389,7 @@ FX_BOOL CPDF_CalRGB::GetRGB(FX_FLOAT* pBuf, FX_FLOAT& R, FX_FLOAT& G, FX_FLOAT&
         Y = B_;
         Z = C_;
     }
-    XYZ_to_sRGB(X, Y, Z, R, G, B);
+    XYZ_to_sRGB_WhitePoint(X, Y, Z, R, G, B, m_WhitePoint[0], m_WhitePoint[1], m_WhitePoint[2]);
     return TRUE;
 }
 FX_BOOL CPDF_CalRGB::SetRGB(FX_FLOAT* pBuf, FX_FLOAT R, FX_FLOAT G, FX_FLOAT B) const