Patent ID: 8947538
Filing Date: 2015-02-03
Classification: H04N

Abstract:
1. A method of generating a measure of quality for a decoded form of a video signal, 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 associated therewith and utilising differential coding such that the encoded signal contains representations of the prediction residual of the signal; and said decoded form in which the encoded video signal has been at least in part reconverted to the original form, the method comprising: generating a quality measure dependent on said quantiser step size parameter according to a predetermined relationship; generating a plurality of masking measures, and applying a weighting to each masking measure, wherein each masking measure is dependent on the spatial complexity of one or more types of regions present in pictures formed by decoding the video signal, and wherein one type of region comprises an active region of a picture in said video sequence for which a prediction residual measure meets a first condition, and at least one other type of region comprises a region of the picture in said video sequence for which said prediction residual measure meets another condition; and combining the quality measure and the plurality of weighted quality masking measures to generate a combined quality measure for the decoded form of the video signal.