Demonstration of compression ratio of over 4000 times for each digital hologram in a sequence of 25 frames in a holographic video

Past research has demonstrated that computer-generated Fresnel holograms can be compressed by over 1600 times based on vector quantization (VQ). In this approach, a digital hologram is first partitioned into non-overlapping square image blocks, each represented as a source vector. Compression is achieved by substituting each source vector with a single index pointing to the nearest member within a small codebook of codevectors. Despite the success, the compression time is rather lengthy, and although the compression ratio can be further increased by enlarging the size of the image block, the quality of the reconstructed image will be degraded significantly. In this paper, we propose a very low bit-rate method for hologram compression based on the integration of VQ, decimation, and the Burrows-Wheeler encoder. Experimental evaluation reveals that our scheme is about 4 times faster than the existing method, and attains higher coding fidelity in terms of quantitative measurement. We also demonstrate an average compression ratio of over 4000 times for each digital hologram in a sequence of 25 frames in a holographic video, maintaining favorable visual quality on the reconstructed images. To our understanding, this is the highest compression ratio that has ever been attained in digital holography. © 2012 IOP Publishing Ltd.