| 摘要 |
<p>The invention relates to estimating the difference in picture quality between two versions of a video signal, one of which has been subject to distortion and the other of which has not been subject to the distortion. The invention has application to estimating the picture quality of a signal subjected to digital compression in comparison to the picture quality of the signal before compression. The estimate of picture quality is obtained by first deriving a difference signal representing the difference between the distorted and undistorted versions of the video signal. A masking signal is obtained by filtering the undistorted version of the video signal and is used to mask the difference signal thereby to derive an output measure of the said difference in picture quality. The masking signal is obtained by filtering the undistorted version of the video signal through a channel including a high-pass edge detection filter. Preferably, a second measure of the difference in picture quality is obtained by applying both the distorted and undistorted versions of the video signal to a circuit that detects block distortion across block boundaries. The output from the block distortion circuit is also masked by the masking signal. <IMAGE></p> |
