Patent ID: 6931067

Claim:
An apparatus for coding an image signal comprising: a wavelet transform unit for wavelet transforming an input image signal; a vector construct unit for constructing vectors using the wavelet transformed result, each vector having a tree structure in a different direction; an error vector generation unit for generating a plurality of error vectors by setting one of the vectors as a basic vector and performing a calculation on each of vectors remaining with respect to the basic vector; a scan unit for scanning the coefficients of each of the basic vector and error vectors in a different direction; a first vector quantization unit for generating a first codebook for the basic vector scanned in the scan unit, quantizing the scanned basic vector using the first codebook, and outputting the quantization result as the index of the first codebook; and a second vector quantization unit for generating a second codebook for the error vectors scanned in the scan unit, quantizing the scanned error vectors using the second codebook, and outputting the quantization results as the indices of the second codebook; wherein: the wavelet transform unit wavelet transforms the input image signal so that the low frequency sub-band of the image signal is decomposed in a 2-dimensional (2D) region; in the vector construct unit the coefficients of vectors having parent-children relations between sub-bands forms a tree structure and the tree structure is formed in the horizontal direction, in the vertical direction, and in the diagonal direction; and the error vector generation unit sets the diagonal direction vector as the basic vector and subtracts each of the horizontal direction vector and vertical direction vector from the basic vector to generate the error vectors.