This paper investigates a combined source-channel encoding of images with a small amount of redundancy. The source encoder under study is based on the Discrete-Cosine-Transform (DCT), adaptive quantization and variabie length encoding (VLC) ;while the channel encoder is based on the unequal error protection (UEP) principle. To measure the importance of each bit in the transmitted frame after the VLC, a factor of sensitivity for each bit to channel errors is defined. By utilizing the factor of sensitivity,the optimal error rate allowed for each bit in the frame, that minimizes the effects of channel noise, is estimated. The performance of two UEP codes constructed by the Blokh-Zyablov code construction method, are evaluated for two sequences of images.
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