FPGA Simulation Research On JPEG Encoder And Decoder

The compression of mass underwater image data is a subject that must be solved with the development of image sonar. Combined with characteristics of underwater image, design and implementation of JPEG encoder and decoder in Quartuss II software using VerilogHDL language is produced in this article.JPEG is a static image compression standard developed jointly by International Organization for Standardization (ISO) and CCITT. It's the most frequently used image storage format.This paper firstly presents based principles of JPEG encoding, then divides module of JPEG encoder from general structure according to encoding flow. Transform of 2D-DCT adopts a fast algorithm based on the conventional row-column decomposition method. DC coefficient encoding employs direct encoding in accordance with characteristics of underwater image. Taking a real underwater image as the test input of JPEG encoder, the code stream outputted by the encoder can display JPEG image correctly after it is programmed by software. Effects and quality of the compressed image are analyzed.JPEG encoder applies symmetrical module division of the JPEG decoder. The algorithm of row-column decomposition is used in the transform of 2D-IDCT as well. According to property of Huffman encoding in JPEG, Huffman decoding adopts the algorithm of Condensed Huffman Table, which reduces the memory resource and enhances decoding speed. Images decoded by the JPEG decoder are compared to the source images, and the results indicate that the design in the paper meet requirements.