lab - EE4115 Audiovisual Engineering Experiment 1....

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Experiment 1. Objective In this laboratory we shall implement a JPEG based image encoder and decoder in C language. After conducting this experiment students should familiarize with the essential building blocks of the JPEG standard. 2. Background of JPEG standard JPEG is composed of a series of stages each providing certain amount of compression as depicted in figure 1. Partition image into image blocks 2D DCT on image blocks Quantization of DCT blocks Zig-zag Coding on AC components Entropy Coding on DC and AC components Bit-stream Construction A B C D E F Raw Image Figure 1 The operations on Steps A to D are illustrated in the CAL package available at http://www.ee.cityu.edu.hk/~csl/aveng/jpeg.exe Two dimensional DCT provides very good energy compactness and de-correlation properties with which the energy of an image sub-block will be concentrated at the low frequency end. Applying quantization will truncate most of the AC coefficients to zero which can be linked up to long sequence of zeros with zig-zag coding. Considerable amount of compression can be achieved with runlength coding which is effective in handling long string of duplicated symbols. Further compression is attained with
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lab - EE4115 Audiovisual Engineering Experiment 1....

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