Unsymmetrical SPIHT Codec and 1D SPIHT Codec

Conventional SPIHT compression is for a 2D image or image block with the same maximum feasible decomposition level in two directions, so, only the size of image or image block is symmetrical, that is to say the maximum feasible decomposition level in two directions must be same and the image sizes had better be equal to 2level such as 32, 64, 128 etc, the optimal compression performance can be acquired. But, in real application, the images are often unsymmetrical, even only have 1 line image data. To overcome the disadvantages of conventional SPIHT codec, this paper proposes two modification versions of SPIHT codec: unsymmetrical SPIHT codec and 1D SPIHT codec, which are adapt to the compression of images with unsymmetrical size and only 1 line image data respectively. Compared with conventional SPIHT, unsymmetrical SPIHT can remove the space redundancy of the image pixels as much as possible for more wavelet decomposition levels are performed, so, a better compression performance can be acquired. 1D SPIHT can encode and decode 1 line image data, which doesn't need a 2D image block and is very suit for hardware design in real time image transmission and compression.