Multi-depth filtering and occlusion suppression in 4-D light fields: Algorithms and architectures

Abstract

Low-complexity signal processing algorithms and reconfigurable digital hardware architectures are proposed for multi-depth filtering and occlusion suppression in 4-D light fields (LFs). The proposed multi-depth-pass (MDP) and multi-depth-reject (MDR) 4-D filters allow simultaneous enhancement of planar objects at multiple desired depths and attenuation of planar objects at multiple undesired depths, thereby achieving electronically tunable multi-depth focusing. Partial-separability and recursive nature of the proposed MDP and MDR transfer functions ensure ultra-low hardware complexity suitable for real-time processing of large volume of input samples encountered in 4-D LFs. Filter synthesis details and examples with synthetic and real LFs of size 15 × 15 × 434 × 625 are presented. A generic framework encapsulating a multitude of possible digital hardware realizations is described, employing J-unfolding and look-ahead pipelining albeit with modifications as applicable to the underlying multi-dimensional signal flow graphs to obtain increased real-time throughput. Proof-of-concept digital designs are provided for the 2-passband case of a MDP filter verifying a real-time throughput of ≈ 490 LFs of size 9 × 9 × 434 × 625 per second for filters operating at 135 MHz on a Xilinx Virtex-7 FPGA device.