Compressive Spectral Imaging Via Virtual Side Information

Abstract

In recent years there has been an increasing interest in compressive imaging devices that capture spectral images with high spatial and spectral resolution with as few as a single snapshot. Nonetheless, there exists an intrinsic trade-off between spatial and spectral resolution which degrades one at the expense of the other. To alleviate this, state-of-art systems have relied on multiple snapshots attained via dynamically programmable spatial light modulators (SLM), or on side information from a second sensor attained via beam-splitters or stereo setups, which suffer from occlusion and demand registration tasks. This work proposes a compressive snapshot spectral imaging architecture that builds on the ideas of side information, but relies on a single image sensor. Specifically, we propose to split the incoming light into two paths, such as in a conventional interferometer, with one path dispersing the coded light, while the other just relaying it, so as to multiplex a traditional coded-and-dispersed measurement with a modulated grayscale version of the 3D cube in the image sensor. We have coined the latter, virtual side information. The proposed optical system is versatile in the sense that it can move from a fully-encoding system, to a spatially modulated grayscale camera, by switching/blocking the splitting response of the beam-splitters. Furthermore, we propose a computational algorithm to recover the underlying spectral cube exploiting the high spatial resolution provided by the virtual side information. We demonstrate through simulations from over fifty spectral images, and via an experimental proof-of-concept implementation, that the proposed imaging system together with the computational algorithm represents an efficient alternative to acquire spectral images without relying on additional sensors.