Using chromaticities if provided #5

afichet · May 27, 2021 · f287e01 · f287e01
1 parent 18c0806
commit f287e01
Showing 1 changed file with 31 additions and 11 deletions.
diff --git a/src/openexr-thumbnailer.cpp b/src/openexr-thumbnailer.cpp
@@ -14,6 +14,9 @@
 
 #include <OpenEXR/ImfRgbaFile.h>
 #include <OpenEXR/ImfArray.h>
+#include <OpenEXR/ImfHeader.h>
+#include <OpenEXR/ImfChromaticitiesAttribute.h>
+
 #include <cmath>
 
 double to_sRGB(double rgb_color)
@@ -31,27 +34,44 @@ unsigned char *load_exr(const char *path, int *width, int *height)
     Imf::Array2D<Imf::Rgba> pixels;
 
     Imf::RgbaInputFile f(path);
-    Imath::Box2i       dw1 = f.dataWindow();
-    int                w   = dw1.max.x - dw1.min.x + 1;
-    int                h   = dw1.max.y - dw1.min.y + 1;
-    *width                 = w;
-    *height                = h;
+    Imath::Box2i       dw = f.dataWindow();
+    int                w  = dw.max.x - dw.min.x + 1;
+    int                h  = dw.max.y - dw.min.y + 1;
+    *width                = w;
+    *height               = h;
 
     pixels.resizeErase(h, w);
-    f.setFrameBuffer(&pixels[0][0] - dw1.min.x - dw1.min.y * w, 1, w);
-    f.readPixels(dw1.min.y, dw1.max.y);
+    f.setFrameBuffer(&pixels[0][0] - dw.min.x - dw.min.y * w, 1, w);
+    f.readPixels(dw.min.y, dw.max.y);
+
+    // Check if there is specific chromaticities tied to the color representation in this part.
+    const Imf::ChromaticitiesAttribute *c = f.header().findTypedAttribute<Imf::ChromaticitiesAttribute>("chromaticities");
+
+    Imf::Chromaticities chromaticities;
+
+    if (c != nullptr) {
+        chromaticities = c->value();
+    }
+
+    // Handle custom chromaticities
+    Imath::M44f RGB_XYZ = Imf::RGBtoXYZ(chromaticities, 1.f);
+    Imath::M44f XYZ_RGB = Imf::XYZtoRGB(Imf::Chromaticities(), 1.f);
+
+    Imath::M44f conversionMatrix = RGB_XYZ * XYZ_RGB;
 
     unsigned char *img = new unsigned char[3 * w * h];
-    //unsigned char* img = calloc(sizeof(unsigned char), 3*w*h);
 
     for (int y = 0; y < h; y++) {
         for (int x = 0; x < w; x++) {
+            Imath::V3f rgb(pixels[y][x].r, pixels[y][x].g, pixels[y][x].b);
+            rgb *= conversionMatrix;
+
             img[3*(y*w + x) + 0] =
-				(unsigned char)(255.0*std::min(1.0, std::max(0.0, to_sRGB(pixels[y][x].r))));
+				(unsigned char)(255.0*std::min(1.0, std::max(0.0, to_sRGB(rgb.x))));
             img[3*(y*w + x) + 1] =
-				(unsigned char)(255.0*std::min(1.0, std::max(0.0, to_sRGB(pixels[y][x].g))));
+				(unsigned char)(255.0*std::min(1.0, std::max(0.0, to_sRGB(rgb.y))));
             img[3*(y*w + x) + 2] =
-				(unsigned char)(255.0*std::min(1.0, std::max(0.0, to_sRGB(pixels[y][x].b))));
+				(unsigned char)(255.0*std::min(1.0, std::max(0.0, to_sRGB(rgb.z))));
         }
     }