Fix PSNRHVS computation
BUG=aomedia:2363
Change-Id: I02504b5a48444d4888c081b1a99ffeb08a2d6b9d
diff --git a/aom_dsp/psnrhvs.c b/aom_dsp/psnrhvs.c
index 30fe21d..2c3d5f7 100644
--- a/aom_dsp/psnrhvs.c
+++ b/aom_dsp/psnrhvs.c
@@ -140,7 +140,7 @@
been normalized and then squared." Their CSF matrix (from PSNR-HVS)
was also constructed from the JPEG matrices. I can not find any obvious
scheme of normalizing to produce their table, but if I multiply their
- CSF by 0.38857 and square the result I get their masking table.
+ CSF by 0.3885746225901003 and square the result I get their masking table.
I have no idea where this constant comes from, but deviating from it
too greatly hurts MOS agreement.
@@ -148,11 +148,15 @@
Jaakko Astola, Vladimir Lukin, "On between-coefficient contrast masking
of DCT basis functions", CD-ROM Proceedings of the Third
International Workshop on Video Processing and Quality Metrics for Consumer
- Electronics VPQM-07, Scottsdale, Arizona, USA, 25-26 January, 2007, 4 p.*/
+ Electronics VPQM-07, Scottsdale, Arizona, USA, 25-26 January, 2007, 4 p.
+
+ Suggested in aomedia issue#2363:
+ 0.3885746225901003 is a reciprocal of the maximum coefficient (2.573509)
+ of the old JPEG based matrix from the paper. Since you are not using that,
+ divide by actual maximum coefficient. */
for (x = 0; x < 8; x++)
for (y = 0; y < 8; y++)
- mask[x][y] =
- (_csf[x][y] * 0.3885746225901003) * (_csf[x][y] * 0.3885746225901003);
+ mask[x][y] = (_csf[x][y] / _csf[1][0]) * (_csf[x][y] / _csf[1][0]);
for (y = 0; y < _h - 7; y += _step) {
for (x = 0; x < _w - 7; x += _step) {
int i;
