Integer transform has been adopted by the newest international video coding standard H.264 for its high efficiency of computation. Our first national audio and video coding standard AVS will also adopt 8×8 integer transform for video compression. As transform module has strong influence on the efficiency of codec

it is important to select an excellent transform basis (transform matrix). In this paper

after introduction of basic theory of DCT-like 8×8 integer transform

the authors bring out three principles of transform basis evaluation: (1) orthogonality

(2) transform efficiency

and (3) computation complexity. First

the transform bases satisfied principle (1) can be found in a predefined data range. Principle (2) is embodied in a novel method combining evaluation of transform efficiency from two aspects: energy compaction and decorrelation efficiency in a proper range of correlation coefficients of input image prediction difference data. By using such evaluation method and taking principle (3)

computation complexity of fast transform algorithm into consideration

several theoretical highly efficient transform bases such as (10

9

6

2)

(5

6

4

1) and (4

5

3

1) have been picked out and tested in the actual video sequences. Based on careful analysis of testing results

the authors find out the proper situation that each basis fits for and prove the validity of transform basis performance measurement that uses this theoretical evaluation method.