Fast and Efficient Restoration of Extremely Dark Light Fields

Mohit Lamba, Kaushik Mitra

Abstract: The ability of Light Field (LF) cameras to capture the 3D geometry of a scene in a single photographic exposure has become central to several applications ranging from passive depth estimation to post-capture refocusing and view synthesis. But these LF applications break down in extreme low-light conditions due to excessive noise and poor image photometry. Existing low-light restoration techniques are inappropriate because they either do not leverage LF’s multi-view perspective or have enormous time and memory complexity. We propose a three-stage network that is simultaneously fast and accurate for real world applications. Our accuracy comes from the fact that our three stage architecture utilizes global, local and view-specific information present in low-light LFs and fuse them using an RNN inspired feedforward network. We are fast because we restore multiple views simultaneously and so require less number of forward passes. Besides these advantages, our network is flexible enough to restore a m × m LF during inference even if trained for a smaller n × n (n < m) LF without any finetuning. Extensive experiments on real low-light LF demonstrate that compared to the current state-of-the-art, our model can achieve up to 1 dB higher restoration PSNR, with 9× speedup, 23% smaller model size and about 5× lower floating-point operations.