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Recovery of relative depth from a single observation using an uncalibrated (real-aperture) camera. Vinay P. Namboodiri Subhasis Chaudhuri Department of Electrical Engineering Indian Institute of Technology, Bombay Powai , Mumbai 400076, India. CVPR 2008. Outline. Introduction
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Recovery of relative depth from a single observation using an uncalibrated(real-aperture) camera Vinay P. NamboodiriSubhasisChaudhuri Department of Electrical Engineering Indian Institute of Technology, Bombay Powai, Mumbai 400076, India. CVPR 2008
Outline • Introduction • Diffusion Based Modeling of Defocus • Reverse Heat Equation • DFD Using Graph Cuts • Results • Ambiguity in Depth Estimation Using Defocus • Conclusion
Introduction • Recovering the depth layers in a scene from a single defocused observation • Common resolution • Multiple observations • This paper • Single observation • Uncalibrated camera
Diffusion Based Modeling of Defocus • Depth from defocus methodology(DFD) • 1987, Pentland • Point spread function (PSF) • The resultant PSF has the general shape of a 2-D Gaussian function • The resultant image the focused image of the scene the blurred observation
Reverse Heat Equation • (1) can be formulated in terms of the isotropic heat equation • The original image • achieved by reversing time the diffusion coefficient the blurred observation
The breakdown of the heat equation is indicated by the degeneration of the gradient • The relative depth in the scene the reverse diffusion time at a location x the approximate estimate of the depth at the location x
DFD Using Graph Cuts • The depth estimate is further refinedby modeling the depth as a Markov random field(MRF)
Results • Atexture image from the Brodatz texture database which is blurred with3 different blur regions • Ageneral outdoor image
A sports scene • A complex lighting conditions
Ambiguity in Depth Estimation Using Defocus • The foreground is out of focus and the background is in focus • The foreground is in focus and the background is out of focus
Conclusion • The reverse heat equation can be used for restoring the image based on the amount of defocus blur • A graph cuts based method is proposed to estimate the depth in the scene thereby enforcing regularization