Error-controlling codes, also called channel coding has been widely applied in various communication system and computer system. And it is the mobile communication system, one of the key technology . LDPC code is comparatively outstanding good yards. Most closely because LDPC code is the channel coding Shannon limit, but also the next generation broadband mobile communication system error correction coding main alternatives. The graduation design mainly through a vast amount of literature review and study, familiar with the definition and principles LDPC code; Two kind of coding method based on triangle matrix under the coding method based on approximate triangular matrices and the coding method, decoding algorithm and it and another kind of Turbo yards of comparison, compare their performance differences and decode complexity. LDPC code in a variety of areas are widely used, For instance (the second generation DVB - S2 satellite digital video broadcast system), CMMB (China mobile multimedia broadcasting), compressed image transmission and digital image watermarking, etc. Through LDPC code in the application of digital image watermarking system based on LDPC code to research the watermarking scheme, This scheme is mainly used to raise the image watermarking robustness, Through the watermark on its principle of coding of more comprehensive study to more in-depth understanding of the digital image LDPC code watermarking system application. Key words: Error-controlling codes LDPC codes Turbo code image watermarking
