fix jni yuvdecoder color

hoozh · hoozh · commit f95800e4a098 · 2014-12-16T16:56:49.000+08:00
diff --git a/library/jni/yuv-decoder.c b/library/jni/yuv-decoder.c
@@ -36,12 +36,23 @@ JNIEXPORT void JNICALL Java_jp_co_cyberagent_android_gpuimage_GPUImageNativeLibr
                              Cr = yuv[cOff + 1];
                              if(Cr < 0) Cr += 127; else Cr -= 128;
                      }
-                     R = Y + Cr + (Cr >> 3) + (Cr >> 6);
-                     if(R < 0) R = 0; else if(R > 255) R = 255;
-                     G = Y - (Cb >> 1) + (Cb >> 4) + (Cb >> 5) - Cr + (Cr >> 2) + (Cr >> 3) + (Cr >> 5) + + (Cr >> 6);
-                     if(G < 0) G = 0; else if(G > 255) G = 255;
-                     B = Y + (Cb << 1) + (Cb >> 5);
-                     if(B < 0) B = 0; else if(B > 255) B = 255;
+                     //==============================
+					 //R = 1.164Y + 2.018Cr;
+					 //G = 1.164Y - 0.813Cb - 0.391Cr;
+					 //B = 1.164Y + 1.596Cb;
+					 //==============================
+					 //===== Approximation ==========
+					 // R = 1.1640625Y + 2.015625Cr
+					 // G = 1.1640625Y - 0.8125Cb - 0.375Cr
+					 // B = 1.1640625Y + 1.59375Cb
+					 //==============================
+                     Y = Y + (Y >> 3) + (Y >> 5) + (Y >> 7);
+					 R = Y + (Cr << 1) + (Cr >> 6);
+					 if(R < 0) R = 0; else if(R > 255) R = 255;
+					 G = Y - Cb + (Cb >> 3) + (Cb >> 4) - (Cr >> 1) + (Cr >> 3);
+					 if(G < 0) G = 0; else if(G > 255) G = 255;
+					 B = Y + Cb + (Cb >> 1) + (Cb >> 4) + (Cb >> 5);
+					 if(B < 0) B = 0; else if(B > 255) B = 255;
                      rgbData[pixPtr++] = 0xff000000 + (R << 16) + (G << 8) + B;
              }
     }
@@ -84,12 +95,23 @@ JNIEXPORT void JNICALL Java_jp_co_cyberagent_android_gpuimage_GPUImageNativeLibr
                              Cr = yuv[cOff + 1];
                              if(Cr < 0) Cr += 127; else Cr -= 128;
                      }
-                     R = Y + Cr + (Cr >> 3) + (Cr >> 6);
-                     if(R < 0) R = 0; else if(R > 255) R = 255;
-                     G = Y - (Cb >> 1) + (Cb >> 4) + (Cb >> 5) - Cr + (Cr >> 2) + (Cr >> 3) + (Cr >> 5) + + (Cr >> 6);
-                     if(G < 0) G = 0; else if(G > 255) G = 255;
-                     B = Y + (Cb << 1) + (Cb >> 5);
-                     if(B < 0) B = 0; else if(B > 255) B = 255;
+                     //==============================
+					 //R = 1.164Y + 2.018Cr;
+					 //G = 1.164Y - 0.813Cb - 0.391Cr;
+					 //B = 1.164Y + 1.596Cb;
+					 //==============================
+					 //===== Approximation ==========
+					 // R = 1.1640625Y + 2.015625Cr
+					 // G = 1.1640625Y - 0.8125Cb - 0.375Cr
+					 // B = 1.1640625Y + 1.59375Cb
+					 //==============================
+                     Y = Y + (Y >> 3) + (Y >> 5) + (Y >> 7);
+					 R = Y + (Cr << 1) + (Cr >> 6);
+					 if(R < 0) R = 0; else if(R > 255) R = 255;
+					 G = Y - Cb + (Cb >> 3) + (Cb >> 4) - (Cr >> 1) + (Cr >> 3);
+					 if(G < 0) G = 0; else if(G > 255) G = 255;
+					 B = Y + Cb + (Cb >> 1) + (Cb >> 4) + (Cb >> 5);
+					 if(B < 0) B = 0; else if(B > 255) B = 255;
                      rgbData[pixPtr++] = 0xff000000 + (B << 16) + (G << 8) + R;
              }
     }
