A GenLOT-based progressive image coder for low resolution images

The popular EZW (embedded zerotree wavelet) and its improved version SPIHT (set partitioning in hierarchical trees) are high-performance progressive transmission image coders based on the wavelet transform which gives excellent compression results for images with significant low-frequency content. For images with high texture contents, the GenLOT-based coder outperforms SPIHT in PSNR measure by a wide margin. On the other hand, low bit rate video finds applications in videophone and surveillance systems, where smaller size image in QCIF format is often transmitted. We show that using the conventional zero-tree algorithm for the QCIF image is suboptimal and we propose several progressive algorithms with modified zero-tree structures. The extensive coding results using both the DCT and GenLOT transform confirms that our proposed modified zero-tree algorithm outperforms the conventional zerotree algorithm for QCIF-sized images