Fix incorrect Rec601 YUV conversion matrix coefficient.

For future reference, the rec 601 matrix can be defined by the concatenation of these 2 matrices:

[1.164  0.0    1.596 0.0]
[1.164 -0.391 -0.813 0.0]
[1.164  2.018  0.0   0.0]
[1.164  0.0    0.0   1.0]
See: http://www.fourcc.org/fccyvrgb.php

and

[1.0  0.0  0.0  -0.0625]
[0.0  1.0  0.0  -0.5   ]
[0.0  0.0  1.0  -0.5   ]
[0.0  0.0  0.0   1.0   ]
Which transforms Y by -0.0625 (-16/256) and U and V by
-0.5 (-128/256) each.

Giving us the final matrix:

[1.164  0.0    1.596  -0.87075]
[1.164 -0.391 -0.813   0.52925]
[1.164  2.018  0.0    -1.08175]
[0.0    0.0    0.0     1.0    ]

Which produces our output [R,G,B,A], when multiplied
with an input [Y,U,V,A].

R=bsalomon@google.com

Author: rileya@chromium.org

Review URL: https://codereview.chromium.org/545983006

diff --git a/src/gpu/effects/GrYUVtoRGBEffect.cpp b/src/gpu/effects/GrYUVtoRGBEffect.cpp
index 0023b1b..4ffc345 100644 (file)
--- a/src/gpu/effects/GrYUVtoRGBEffect.cpp
+++ b/src/gpu/effects/GrYUVtoRGBEffect.cpp
@@ -132,8 +132,8 @@ const GrGLfloat YUVtoRGBEffect::GLEffect::kJPEGConversionMatrix[16] = {
     1.0f,  1.772f,    0.0f,    -0.886f,
     0.0f,  0.0f,      0.0f,     1.0};
 const GrGLfloat YUVtoRGBEffect::GLEffect::kRec601ConversionMatrix[16] = {
-    1.164f,  0.0f,    1.596f, -1.08175f,
-    1.164f, -0.391f, -0.813f,  0.529f,
+    1.164f,  0.0f,    1.596f, -0.87075f,
+    1.164f, -0.391f, -0.813f,  0.52925f,
     1.164f,  2.018f,  0.0f,   -1.08175f,
     0.0f,    0.0f,    0.0f,    1.0};
 }