In-loop denoising of reference frames for lossless coding of noisy image sequences

The major gain in video coding applications compared to single image coding is the use of temporal prediction, which exploits the correlation between adjacent frames. However, in high quality video coding, especially lossless video coding, the compression gain of P-frames over I-Frames becomes very small. The reason for that is that the reference frame for inter prediction is not good enough, and therefore the amount of inter-predicted blocks in a P-Frame becomes relatively small compared to the number of intra-predicted blocks. In order to generate a better predictor for inter-prediction, we propose to remove additive noise from the reference frame using an adaptive Wiener filter. This way, we could achieve a maximum compression gain of 4.6% and an average compression gain of 3.3% in contrast to the H.264/AVC standard for lossless coding of high quality image sequences without affecting the encoding time noticeably.