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Green Image
Issue No. 04 - April (2011 vol. 33)
ISSN: 0162-8828
pp: 671-686
Ashok Veeraraghavan , Mitsubishi Electric Research Labs, Cambridge
Dikpal Reddy , University of Maryland, College Park
Ramesh Raskar , Massachusettes Institute of Technology, Cambridge
We show that, via temporal modulation, one can observe and capture a high-speed periodic video well beyond the abilities of a low-frame-rate camera. By strobing the exposure with unique sequences within the integration time of each frame, we take coded projections of dynamic events. From a sequence of such frames, we reconstruct a high-speed video of the high-frequency periodic process. Strobing is used in entertainment, medical imaging, and industrial inspection to generate lower beat frequencies. But this is limited to scenes with a detectable single dominant frequency and requires high-intensity lighting. In this paper, we address the problem of sub-Nyquist sampling of periodic signals and show designs to capture and reconstruct such signals. The key result is that for such signals, the Nyquist rate constraint can be imposed on the strobe rate rather than the sensor rate. The technique is based on intentional aliasing of the frequency components of the periodic signal while the reconstruction algorithm exploits recent advances in sparse representations and compressive sensing. We exploit the sparsity of periodic signals in the Fourier domain to develop reconstruction algorithms that are inspired by compressive sensing.
Computational imaging, high-speed imaging, compressive sensing, compressive video sensing, stroboscopy.

R. Raskar, D. Reddy and A. Veeraraghavan, "Coded Strobing Photography: Compressive Sensing of High Speed Periodic Videos," in IEEE Transactions on Pattern Analysis & Machine Intelligence, vol. 33, no. , pp. 671-686, 2010.
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