Detection of uniform video frames by summing oppositely signed weighted data value ranges

摘要

Images are analysed to determine whether image data values are close to a defined value. A plurality of sample value ranges corresponding to luminance values, for example, is defined and the pixels of a frame are allocated to the ranges depending on their values. Each range has a weight assigned to it, the sample value range including the defined value having a weight of opposite sign to the weight assigned to at least one other sample value range. A weighted sum of the data values is thus produced and tested against a threshold value. A positive result is determined if the sum is less than the threshold when the weight of the sample value range containing the define value is negative or if the sum is more than the threshold when the weight of the sample value range containing the define value is positive. The invention finds application in detecting black frames in video data, for example, in order to detect when errors have occurred.