Method for detection and quantification of picture modification in a video picture processed by block based data reduction of video-code

For detecting and quantifying image changes of a video image processed with a block-based, data-reducing encoding method,First, the difference of the amplitude values ​​of the horizontally and / or vertically adjacent pixel pairs of the video image is determined;for all pixel pairs lying in the same relation to the block grid, the mean value of these difference amounts is then determined;then the average of the mean values ​​within the coding blocks is determinedand finally, this average value is compared with the mean of the difference amounts at the block boundary.