S. Minasyan, J. Astola, and D. Guevorkian (Finland)
discrete orthogonal transform, image coding, adaptive transform.
In this paper we present a new image compression technique using multiple transforms. In particular, the Discrete Cosine Transform (DCT) and three fast orthogonal parametrically adaptive Haar-like transforms are used. A Haar-like transform is a discrete orthogonal transform such that it may be computed by a fast algorithm. with structure similar to that of classical fast Haar transform, and such that its matrix contains one or more predefined rows or columns of an arbitrary order. The nature of the proposed image compression scheme is such that its performance (in terms of PSNR versus compression ratio) at least is the same or better than that of the classical DCT based compression scheme, e.g. JPEG. Simulations show that significant performance improvement can be achieved for certain types of images such as compound documents.
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