Livrable D3.3 of the PERSEE project : 2D coding tools

49Livrable D3.3 du projet ANR PERSEECe rapport a été réalisé dans le cadre du projet ANR PERSEE (n° ANR-09-BLAN-0170). Exactement il correspond au livrable D3.3 du projet. Son titre : 2D coding tool

Quality Adaptive Least Squares Trained Filters for Video Compression Artifacts Removal Using a No-reference Block Visibility Metric

Compression artifacts removal is a challenging problem because videos can be compressed at different qualities. In this paper, a least squares approach that is self-adaptive to the visual quality of the input sequence is proposed. For compression artifacts, the visual quality of an image is measured by a no-reference block visibility metric. According to the blockiness visibility of an input image, an appropriate set of filter coefficients that are trained beforehand is selected for optimally removing coding artifacts and reconstructing object details. The performance of the proposed algorithm is evaluated on a variety of sequences compressed at different qualities in comparison to several other deblocking techniques. The proposed method outperforms the others significantly both objectively and subjectively

Poboljšana adaptivna pretvorba ostataka prilikom H.264/AVC video kodiranja bez gubitka kvalitete

The H.264/AVC was designed mainly for lossy video coding, the lossless coding of H.264 use bypass mode for DCT and quantization. Although sample-by-sample DPCM improves performance of coding, the benefit is limited in intra. In this paper, a new adaptive transform is proposed based on the character of 4x block residual coefficient\u27s distribution, which can be used both in intra and inter coding. The greatest strength of the proposed transform is the decorrelation without inflation versus dynamic range of input matrix. Due to the random distribution of residual coefficients, a specific transform is hard to play a positive impact on them. Therefore, several transforms of different directions will be implemented simultaneously, and the most efficient one will be determined by a proposed mechanism. Then, by means of statistic method, a new scan order is designed for CAVLC entropy encoder, cooperating with corresponding transform. The simulation results show that based on the fast algorithm of proposed method, the bit saving achieves about 7.41% bit saving in intra coding and 10.47% in inter, compared with H.264-LS.H.264/AVC je napravljen prvenstveno za kodiranje videa uz gubitak kvalitete, dok kodiranje H.264 bez gubitka kvalitete koristi zaobilazni mod za DCT i kvantizaciju. Iako uzorak-po-uzorak (DPCM) kvantizacija poboljšava performanse kodiranja, dobitak je ograničen. U ovom radu predlaže se nova adaptivna transformacija koja se zasniva na znakovima od 4x4 blokova distribucije ostataka koeficijenata, koja može koristiti i unutarnje i među kodiranje. Najveća snaga predložene transformacije je u nekoreliranosti bez inflacije protiv dinamičke veličine ulazne matrice. Radi slučajne distribucije ostataka koeficijenata, teško je postići da određena transformacija ima pozitivan učinak na njih. Iz tog razloga istovremeno je implementirano nekoliko transformacija različitih pristupa, te je korištenjem predloženog mehanizma odabrana najefikasnija. Zatim je, korištenjem statističke metode, dizajniran novi poredak snimanja za CAVLC entropijski enkoder, koji surađuje s odgovarajućom transformacijom. Rezultati simulacija pokazuju da korištenjem brzog algoritma predložene metode dolazi do smanjenja korištenih bitova od 7.41% kod među kodiranja i 10.47% prilikom unutarnjeg kodiranja u usporedbi s H.264-LS