A Fast and Memory Efficient SPIHT Image Encoder

Set-partitioning in hierarchical trees (SPIHT) is one of the well-known image compression schemes. SPIHT offers an agreeable compression ratio and produces an embedded bit-stream for progressive transmission. However, the major disadvantage of SPIHT is its large memory requirement. In this paper, we propose a memory efficient SPIHT image coder and its parallel implantation. The memory requirement is reduced without sacrificing image quality. All bit-planes are concurrently encoded in order to speed up the entire coding flow. The result shows that the proposed algorithm is roughly 6 times faster than the original SPIHT. For a 512 x 512 image, the memory requirement is reduced from 5.83 Mb to 491 Kb. The proposed algorithm is also realized on FPGA. With pipeline design, the circuit can run at 110 MHz, which can encode a 512x512 image in 1.438 ms. Thus, the circuit achieves very high throughput, 182 MPixels/sec, and can be applied to high performance image compression applications.