Low bit-rate compression of video and light-field data using coded snapshots and learned dictionaries
The method of coded snapshots has been proposed recently for compressive acquisition of video data to overcome the space-time trade-of inherent in video acquisition. The method involves modulation of the light entering the video camera at different time instants during the exposure period by means of a different and randomly generated code pattern at each of those time instants, followed by integration across time, leading to a single coded snapshot image. Given this image and knowledge of the random codes, it is possible to reconstruct the underlying video frames - by means of sparse coding on a suitably learned dictionary. In this paper, we apply a modified version of this idea, proposed formerly in the compressive sensing literature, to the task of compression of videos and light-field data. At low bit rates, we demonstrate markedly better reconstruction fidelity for the same storage costs, in comparison to JPEG2000 and MPEG-4 (H.264) on light-field and video data respectively. Our technique can cope with overlapping blocks of image data, thereby leading to suppression of block artifacts.