Noise power estimation for effective de-noising in a video encoder

This paper presents a noise estimation algorithm using multiresolution motion estimation in a video encoder. Firstly, the motion estimator finds minimum block-matching errors at the finest resolution and the middle resolution for each macroblock. Secondly, if the minimum block-matching error at the finest resolution of a certain macroblock is less than a particular threshold, the variance of the inter-macroblock is computed. And then, we employ the square of the minimum block-matching error at the middle resolution as a predictor of the variance of the desired inter-macroblock without noise. The noise variance in the macroblock can be estimated by subtracting the predictor from the variance of the inter-macroblock. Finally, the noise variances estimated only for the well-motion-compensated macroblocks are averaged in each frame. Experimental results show that the proposed noise estimation is very accurate with negligible computational cost.