Unequally Protected Packet Transmission of SPIHT-Compressed Images

摘要

In combination with the discrete wavelet transform (DWT), set partitioning in hierarchical trees (SPIHT) is one of the most renowned techniques for image compression. One problem with SPIHT, however, is that its decoding can be extremely sensitive to errors in its embedded bit stream. In this paper, we address the issue of transmitting SPIHT-encoded images in packets via erasure channels, wherein each received packet is either error-free or totally discarded. In our scheme, the original SPIHT code sequence is packetized (into two types: critical packet (CP) and refinement packet (RP)). Those packets are then allocated with different diversity orders for unequal error protection (UEP) so that the decoded image is expected to attain the highest signal-to-noise ratio (SNR) at the receiver. Simulations show that the proposed scheme significantly improves the decoded images as compared to the case of no diversity allocation and the case of not distinguishing between CP and RP.