Practical Low Bit Rate Predictive Image Coder Using Multi-Rate Processing and Adaptive Entropy Coding (WP-P1)

Author(s) : Anna N. Kim (Norwegian University of Science and Technology, Norway) Tor A. Ramstad (Norwegian University of Science and Technology, Norway)

Abstract : The modified Differential Pulse Coded Modulation (DPCM) codec with multi-rate processing was shown to able to code source with monotonically decreasing spectrum efficiently at low bit rates. A practical image coder is designed based on this approach. Two dimensional DPCM is used along with decimation and interpolation to reduce the number of transmitted samples. The decimation rate depends on the signal spectrum and the bit rate. Further bit rate reduction is achieved through adaptive entropy coding. Wiener filter is appended in the decoder for minimizing distortion caused by quantization noise. The image coder can be implemented using simple IIR filters. The necessary side information is low. Simulation results show that the coder is able to give good compression performance at low bit rates which is superior than conventional DPCM codec and JPEG.

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