Soft Decoding of Light Field Images Using Pocs and Fast Graph Spectrayl Filters
Shuai Yang, Gene Cheung, Jiaying Liu, Zongming Guo · 2018
Light field data captured by a lenslet-based image sensor is typically demosaicked, aligned and rearranged into a series of sub-aperture (viewpoint) images, before a disparity-compensated coding scheme is employed for compression. In this paper, we focus on the problem of soft decoding of block-based compressed sub-aperture images at the decoder: given quantization bin indices of DCT coefficients of non-overlapping code blocks, we select appropriate coefficient values that are low-pass filtered using graph spectral filters and view-consistent across sub-aperture images via projection on convex sets (POCS). Specifically, after an initial pixel estimate, we low-pass filter each pixel block using accelerated graph filters based on the Lanczos method. We then map filtered pixels to a neighborhood of sub-aperture images based on estimated disparity to enforce indexed quantization bin constraints of multiple images. Experimental results show that our algorithm achieves PSNR gain of 2.34dB over JPEG hard decoding.