A new approach to compatible Adaptive Block-size Transforms

Adaptive Block-size Transforms (ABT) has been widely used in image/video coding, since it exploits the maximum feasible signal length for transform coding. However, if the transforms in an ABT coding system are Integer Cosine Transforrns (ICT), not only separate transform units but also different scaling matrices are required, which consume a vast amount of resources in practical implementations. In this paper, a new approach to compatible ABT is presented, by which 84, 8X4, 4X8 and 4X4 transforms can be processed in one transform unit. Furthermore, with Pre-scaled Integer Transform (PIT), the compatibility of scaling matrices especially for 8X4 and 4X8 ICT can be achieved and a single scaling matrix is required. Simulation results and analysis reveal that this approach greatly saves hardware resources and makes the implementation of ABT much easier without loss of performance.