A Novel Design of Regular Cosine-Modulated Filter Banks for Image Coding

概要

論文の詳細を見る
This paper describes a design method of cosine-modulated filter banks (CMFBs) for an efficient coding of images. Whereas the CMFB has advantages of low design and implementation cost, subband filters of the CMFB do not have linear phase property. This prevents from employing a symmetric extension in transformation process, and leads to a degradation of the image compression performance. However, a recently proposed smooth extension alleviates the problem with CMFBs. As a result, well-designed CMFBs can be expected to be good candidates for a transform block in image compression applications. In this paper, we present a novel design approach of regular CMFBs. After introducing a regularity constraint on lattice parameters of a prototype filter in paraunitary (PU) CMFBs, we also derive a regularity condition for perfect reconstruction (PR) CMFBs. Finally, we design regular 8-channel PUCMFB and PRCMFB by an unconstrained optimization of residual lattice parameters, and several simulation results for test images are compared with various transforms for evaluating the proposed image coder based on the CMFBs with one degree of regularity. In addition, we show a computational complexity of the designed CMFBs.
2009-07-01