Zerotree coding of wavelet coefficients for image data on arbitrarily shaped support

Abstract

[Summary form only given]. A wavelet coding method for arbitrarily shaped image data, applicable to object-oriented coding of moving pictures, and to the efficient representation of texture data in computer graphics is proposed. The wavelet transform of an arbitrarily shaped image is obtained by applying the symmetrical extension technique at region boundaries and keeping the location of the wavelet coefficient. For entropy coding of the wavelet coefficients, the zerotree coding technique is modified to work with arbitrarily shaped regions by treating missing (outside of the decomposed support) coefficients as insignificant and transmitting only those zerotree symbols which are in the decomposed support. The coding performance of the proposed method for several test images that include a person, a teapot and a necklace is compared to a shape-adaptive DCT and an ordinary DCT method applying low pass extrapolation to the DCT block containing the region boundaries. Experiments show that the proposed method has a better coding efficiency compared to SA-DCT and the ordinary DCT method.