RLFC: Random Access Light Field Compression using Key Views and Bounded Integer Sequence Encoding
We present a new hierarchical compression scheme for encoding light field images (LFI) that is suitable for interactive rendering.
Our method (RLFC) exploits redundancies in the light field images by constructing a tree structure. The top level (root) of the tree captures the
common high-level details across the LFI, and other levels (children) of the tree capture specific low-level details of the LFI. Our
decompressing algorithm corresponds to tree traversal operations and gathers the values stored at different levels of the tree. Furthermore,
we use bounded integer sequence encoding which provides random access and fast hardware decoding for compressing the blocks of children of the tree.
We have evaluated our method for 4D two-plane parameterized light fields. The compression rates vary from 0.08 - 2.5 bits per pixel (bpp), resulting
in compression ratios of around 200:1 to 20:1 for a PSNR quality of 40 to 50 dB. The decompression times for decoding the blocks of LFI are 1-3
microseconds per channel on an NVIDIA GTX-960 and we can render new views with a resolution of 512X512 at 200 fps. Our overall scheme
is simple to implement and involves only bit manipulations and integer arithmetic operations. Comparison figure.
HMLFC: Hierarchical Motion-Compensated Light Field Compression for Interactive Rendering
Abstract: We present a new motion-compensated hierarchical compression scheme (HMLFC) for encoding light field images (LFI) that is suitable for interactive rendering. Our method combines two different approaches, motion compensation schemes and hierarchical compression methods, to exploit redundancies in LFI. The motion compensation schemes capture the redundancies in local regions of the LFI efficiently (local coherence) and hierarchical schemes capture the redundancies present across the entire LFI (global coherence). Our hybrid approach combines the two schemes effectively capturing both local as well as global coherence to improve the overall compression rate. We compute a tree from LFI using a hierarchical scheme and use phase shifted motion compensation techniques at each level of the hierarchy. Our representation provides random access to the pixel values of the light field, which makes it suitable for interactive rendering applications using a small run-time memory footprint. Our approach is GPU friendly and allows parallel decoding of LF pixel values. We highlight the performance on the two-plane parameterized light fields and obtain a compression ratio of 30-800X with a PSNR of 40-45 dB. Overall, we observe a 2-5X improvement in compression rates using HMLFC over prior light field compression schemes that provide random access capability. In practice, our algorithm can render new views of resolution 512X512 on an NVIDIA GTX-980 at ~200 fps.