Patent ID: 8254438

Claim:
A method of generating a measure of quality for a video signal representative of a plurality of frames, the video signal having: an original form; an encoded form in which the video signal has been encoded using a compression algorithm utilising a variable quantiser step size such that the encoded signal has a quantiser step size parameter associable therewith; and, a decoded form in which the encoded video signal has been at least in part reconverted to the original form, the method comprising: a) generating a first quality measure which is a function of said quantiser step size parameter; b) from the video signal in the decoded form, generating a second quality measure as a function of the spatial complexity of at least part of a given frame for at least some of the pixels in that frame, determined from a measure of changes in intensity in a first direction at a given pixel, and changes in intensity at that pixel in a second direction; and c) combining the first and second measures.