Noise reduction apparatus

摘要

In picture decoding from compressed data, a noise component is predicted for each pixel and noise-free original picture data is derived from the predicted noise component and the decoded picture data. An activity calculation circuit (11) derives the horizontal activity (i.e. variation in luminance magnitude) of block-based decoded picture data, and a block mean noise prediction circuit (12) predicts black mean noise according to the activity obtained in the activity calculation circuit (11) and a block quantisation step. A pixel noise prediction circuit (13) derives predicted noise in each pixel from the predicted block mean noise obtained in the block mean noise prediction circuit (12) and the activity obtained in the activity calculation circuit. A filter coefficient determining circuit (14) determines filter coefficients and a filter circuit (15) predicts and outputs noise-free picture data. The horizontal noise reduction circuit (21) is followed by a vertical noise reduction circuit 22, although their order is not critical.