JPEG Encoder Decoder

image encode/decode using DCT, quantization, zigzag reordering & run-level coding of JPEG standard

This is a JPEG encoding & decoding program of still image. It does not use level shifting. Discrete Cosine transform (DCT) is performed both by classical & Chen's Flowgraph methods. Predefined JPEG quantization array & zigzag order are used here. 'RUN' - 'LEVEL' coding is used instead of Huffman coding. Compression ratio is compared for each DCT method. Effect of coarse and fine quantization is also examined. The execution time of 2 DCT methods is also checked. In addition, most energatic DCT coefficients are also applied to examine the effect in MatLab 7.4.0 R2007a. Input is 9 gray scale pictures & output is 9*9=81 pictures to compare. Blocking effect is obvious.