Low Bit-Rate Subpixel-Based Color Image Compression

We propose a novel low bit-rate compression scheme with sub pixel-based down-sampling and reconstruction (SPDR) for full color images. In the encoder stage, a decoder-dependent multi-channel sub pixel-based down-sampling is proposed, which is more effective in retaining high frequency detail than conventional pixel-based process. The decoder first decompresses the low-resolution image and then up-converts it to the original resolution using encoder dependent sub pixel-based reconstruction scheme by jointly considering the sub pixel-based down-sampling effect and the compression degradation. Compared to existing algorithms with comparable encoder and decoder complexity, the proposed SPDR offers complete standard compliance, competitive rate-distortion performance, and superior subjective quality.