Intra-mode indexed nonuniform quantization parameter matrices in AVC/H.264

We generate nonuniform quantization parameter(QP) matrices to improve the perceptual quality of reconstructed video in the AVC/H.264 standard. The resulting 9 QP matrices are indexed to the 9 intra-frame prediction modes of the 4 x 4 blocks and can be applied to the 16 x 16 macroblock(MB)s which engage only the first 4 out of the 9 intra-modes. We also studied how the nonuniform QP matrices are affected by the local luminance level and the video frame rate. Two subjective experiments exploiting the luminance, texture, and temporal masking properties of the human vision system are conducted to generate the results. A third subjective experiment is conducted to evaluate the derived scheme. The data we collect from this experiment show that using the QP matrices instead of a uniform QP considerably improves the perceptual quality of AVC/H.264 compressed video sequences. Some implementation details are discussed.