Spatial Combinative Lifting Algorithm-Based Block Wavelet Transform for Image Compression

In order to reduce the memory required by the global wavelet transform, an efficient block wavelet transform method for image coding is proposed. The image is partitioned into blocks and each block is processed independently. The data of neighboring blocks are used as overlapped part between neighboring blocks for block wavelet transform to avoid edge artifact. In each overlapped block, in order to reduce the increased operations caused by overlapped part, the spatial combinative lifting algorithm (SCLA) is used for performing the wavelet transform. Compared with the lifting-based global wavelet transform, the memory requirement of this SCLA-based block wavelet transform is reduced to the size of the overlapped block and the multiplication operations are also reduced when the block size is larger than sixteenth of the whole image size. The proposed block wavelet transform method is especially efficient for compressing large sized images.