Andrew Church wrote: > Just as an addendum (though I think it's been mentioned on this list > before), PSNR isn't always a good measurement of visual quality, so take > these results with a grain of salt. Lower PSNR generally means lower > visual quality, but depending on the actual image data, deliberate > "errors" such as averaging pixels can help the brain fill in the missing > detail on its own, causing the image to look better to a human viewer.
This is a very important point! Depending upon the source, a significantly lower PSNR can look dramatically better - When transcoding from VHS source, for example. PSNR is mostly useful for things like determining whether 2-pass encoding in x264 works or not ;^)
