Quadtree-based transform coding for multispectral image compression
Jungwoo Lee · Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 1996
A new multispectral image compression technique based on the KLT and the DCT is proposed. The quadtree for determining the block size and the quantizer for encoding the transform coefficients are jointly optimized in a rate-distortion sense. The problem is solved by a Lagrange multiplier approach. This approach was also used in an optimal MPEG encoding problem by the author. After a quadtree is determined by this approach, the KLT is applied to the spectral axis for each block before the DCT is applied on the spatial domain. The eigenvectors of the autocovariance matrix, the quantization scale, and the quantized transform coefficients for each block are the output of the encoder. The overhead information required in this scheme is the bits for the quadtree representation.