Sub-band coding with improved permutation codes for high fidelity image compression

Sub-band image coding is considered to be a promising technique for high fidelity compression of high resolution images. In the traditional sub-band image coding algorithm where a scalar quantizer is used, high frequency sub-band signals are usually discarded, which incurs rather noticeable degradation of reconstruction quality. To solve this problem, the authors introduce improved permutation codes, developed by extending the concept of prototypal permutation codes into sub-band image-coding. Improved permutation codes are used to quantized high frequency sub-band signals. The simulation results demonstrate that improved permutation codes are more useful than an entropy-constrained scalar quantizer as a means for quantizing high frequency sub-band signals. An adaptive quantization technique combining improved permutation codes and entropy-constrained scalar quantizers is developed, and its usefulness is demonstrated by computer simulations