The Joint Collaborative Team on Video Coding (jct-vc) of itu-t wp3/16 and iso/iec jtc 1/sc 29/wg 11 held its second meeting during 21-28 July, 2010 at the itu-t premises in Geneva, ch

5.8Residual transforms

JCTVC-B024 [C. Yeo, Y. H. Tan, Z. Li, S. Rahardja (I2R)] Mode-dependent fast separable KLT for block-based intra coding

Mode-Dependent Directional Transform (MDDT) was previously introduced to improve transform coding of intra-predicted blocks [1], and is now a core component of the Test Model under Consideration (TMuC) [2]. This proposal presents a simplification of the MDDT scheme that requires only two transform matrices: a DCT and a derived KLT. The derived 4x4 KLT also has a structure that can be exploited to reduce the operation count of the transform operation. Derivation of the KLT is based on an assumed image correlation model. Experimental results show that the proposed technique matches the performance of MDDT even though the approach requires no training, and has significantly lower computation and storage costs.

Proposal to replace MDDT (consisting of two separable KLT bases) by a separable transform that consists of a DCT and a KLT (both implemented as integer transforms). DCT as fast algorithm, KLT also reducing computations by half compared to full matrix multiplications.

Implemented in KTA, performance very similar to the MDDT that is implemented there (different in range of +/- 0.3% BR fluctuation, by tendency sightly better for large and slightly worse fo small resolutions. (Note: The MDDT of KTA was optimized with QCIF, whereas the MDDT of TMuC is different)

Recommendation: TE establishment.