Gabay Abraham Avi, Kieffer Michel, Duhamel Pierre
The authors are with Laboratoire des Signaux et Systèmes, CNRS - Supélec- Univ Paris-Sud, 91192 Gif-sur-Yvette, France.
IEEE Trans Image Process. 2007 Jun;16(6):1568-83. doi: 10.1109/tip.2007.896698.
In this paper, a new still image coding scheme is presented. In contrast with standard tandem coding schemes, where the redundancy is introduced after source coding, it is introduced before source coding using real BCH codes. A joint channel model is first presented. The model corresponds to a memoryless mixture of Gaussian and Bernoulli-Gaussian noise. It may represent the source coder, the channel coder, the physical channel, and their corresponding decoder. Decoding algorithms are derived from this channel model and compared to a state-of-art real BCH decoding scheme. A further comparison with two reference tandem coding schemes and the proposed joint coding scheme for the robust transmission of still images has been presented. When the tandem scheme is not accurately tuned, the joint coding scheme outperforms the tandem scheme in all situations. Compared to a tandem scheme well tuned for a given channel situation, the joint coding scheme shows an increased robustness as the channel conditions worsen. The soft performance degradation observed when the channel worsens gives an additional advantage to the joint source-channel coding scheme for fading channels, since a reconstruction with moderate quality may be still possible, even if the channel is in a deep fade.
本文提出了一种新的静止图像编码方案。与标准串联编码方案不同，标准串联编码方案在源编码之后引入冗余，而该方案使用实BCH码在源编码之前引入冗余。首先提出了一种联合信道模型。该模型对应于高斯噪声和伯努利 - 高斯噪声的无记忆混合。它可以表示源编码器、信道编码器、物理信道及其相应的解码器。从该信道模型推导了解码算法，并与一种先进的实BCH解码方案进行了比较。还给出了与两种参考串联编码方案以及所提出的用于静止图像鲁棒传输的联合编码方案的进一步比较。当串联方案未精确调谐时，联合编码方案在所有情况下都优于串联方案。与针对给定信道情况调谐良好的串联方案相比，随着信道条件恶化，联合编码方案表现出更高的鲁棒性。当信道恶化时观察到的软性能下降为衰落信道的联合信源 - 信道编码方案带来了额外优势，因为即使信道处于深度衰落，仍可能实现中等质量的重建。
