Towards Digital Refocusing from a Single Photograph

Yosuke Bando		Tomoyuki Nishita
TOSHIBA Corporation The University of Tokyo		The University of Tokyo

This paper explores an image processing method for synthesizing refocused images from a single input photograph containing some defocus blur. First, we restore a sharp image by estimating and removing spatially-variant defocus blur in an input photograph. To do this, we propose a local blur estimation method able to handle abrupt blur changes at depth discontinuities in a scene, and we also present an efficient blur removal method that significantly speeds up the existing deconvolution algorithm. Once a sharp image is restored, refocused images can be interactively created by adding different defocus blur to it based on the estimated blur, so that users can intuitively change focus and depth-of-field of the input photograph. Although information available from a single photograph is highly insufficient for fully correct refocusing, the results show that visually plausible refocused images can be obtained.

Paper (2.8MB, PDF):
Proceedings of the 15th Pacific Conference on Computer Graphics and Applications (Pacific Graphics 2007), pp. 363-372, 2007.

From a single input photograph (left), images focused to different depths can be synthesized (middle and right).
Video (3.2MB, WMV):
Users can interactively change the focus and depth-of-field of photographs with a few intuitive parameters and an auto-focusing capability.
Comparison with a real photograph:
Digital refocusing from a single photograph can simulate optical refocusing with a real camera.

An input photograph (left) can be digitally refocused (middle) so that it closely resembles a reference photograph (right).
Additional results:
Results produced after the publication.
Deconvolution code (240KB, ZIP):
C source code of the gradient domain (non-blind) deconvolution.

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