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Bilateral Filtering for Video Coding Per Wennersten, Jacob Ström, Ying Wang, Kenneth Andersson, Rickard Sjöberg and Jack Enhorn original anchor proposed Ringing artifacts 0 5 10 15 20 25 30 35 40 20 40 60 80 100 120 140 160 180 original −10 0 10 20 30 40 50 −300 −200 −100 0 100 200 300 400 500 600 700 transformed −10 0 10 20 30 40 50 −300 −200 −100 0 100 200 300 400 500 600 700 quantized transform 0 5 10 15 20 25 30 35 40 20 40 60 80 100 120 140 160 180 reconstructed transform quantize inverse transform artifacts Tools that counter ringing • Sample Adaptive Offset (SAO) Fu et al. [5] • Adaptive Loop Filtering (ALF) Tsai et al. [4] Bilateral Filtering (Tomasi Mandutchi [7]) 36 1 1 6 1 6 1 6 6 1 64 The weight of a FIR filter depends only on position weight spatial distance intensity distance original FIR filtering bilateral filtering Main idea • Main contributions Proposal to set σ d using TU size and σ r using QP. Use bilateral filtering after reconstruction to reduce ringing • iDCT c ij clip [0,255] prediction bilateral filter recon- structed samples Complexity reductions that give a good trade-off between coding gain and complexity. • Complexity reductions • Use small filter kernel • Use look-up table LUT(σ d , σ r , ΔI) • Use math trick to reuse LUT table LUT(σ d , σ r , ΔI) LUT(σ r , ΔI) • Use table to turn division into multiplication ÷ * Results BD-rate intra inter -0.4% -0.5% +6% +3% +5% +0% encoder decoder complexity LUT size needed: 2778 bytes
