The Image Compression Coding Technic And Memory In The Free-Space Laser Communication

In this paper, firstly the character of the Fourier Transform and Wavelet Transform is analyzed in detail, and a method to compress the image using Discrete Wavelet Transform is discussed, then the method based wavelet SPIHT is expatiated in emphases. At last, the joint source channel coding scheme based on SPIHT is put forward. This method provides unequal protection for SPIHT bet stream with different importance, and adaptively adjusts the source and channel coding rates according to the time-varying characteristic of the channel, thus yields good performance and high reliability without adding extra bandwidth. Simulations in Rayleigh channel show that the scheme can obviously improve the image quality compared to EEP and UEP scheme, especially when the channel is in bad condition.