ycbcr2rgb

python/ftl/ftlstream.py

@@ -25,7 +25,7 @@ except ImportError:
         ''' YCrCb to RGB, based on OpenCV documentation definition.
         
         Note: It seems this implementation is not perfectly equivalent to
-        OpenCV's
+        OpenCV's (results not exactly same, why?)
         '''
         
         rgb = np.zeros(img.shape, np.float)
@@ -41,6 +41,20 @@ except ImportError:
 
         return rgb.round().astype(np.uint8)
 
+def _ycbcr2rgb(img):
+    rgb = np.zeros(img.shape, np.float)
+
+    Y = img[:,:,0].astype(np.float)
+    Cr = img[:,:,2].astype(np.float)
+    Cb = img[:,:,1].astype(np.float)
+    delta = 128.0
+
+    rgb[:,:,0] = Y + 1.403 * (Cr - delta)
+    rgb[:,:,1] = Y - 0.714 * (Cr - delta) - 0.344 * (Cb - delta)
+    rgb[:,:,2] = Y + 1.773 * (Cb - delta)
+
+    return rgb.round().astype(np.uint8)
+
 class FTLStreamWriter:
     def __init__(self, file, version=2):
         self._file = open(file, "wb")
@@ -237,7 +251,7 @@ class FTLStreamReader:
             if self._version < 3:
                 self._frame = _ycrcb2rgb(img)
             else:
-                self._frame = img
+                self._frame = _ycbcr2rgb(img)
 
     def _decode_opencv(self, sp, p):
         try: