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Microsoft Tech Can Deblur Images Automatically
An anonymous reader writes "At the annual SIGGRAPH show, Microsoft Research showed new technology that can remove the blur from images on your camera or phone using on-board sensors — the same sensors currently added to the iPhone 4. No more blurry low light photos!"
Microsoft Research puts out a lot of really interesting and successful research. They aren't the people programming the OS or office applications.
It won't help at all if the object is moving. In fact, this feature should be switched off if you're trying to photograph a moving object with the camera (common enough, and not just in sports). It would not be able to compensate for a mismatch between the object speed and your tracking movement, and would do entirely the wrong thing even if you tracked the moving object perfectly for the shot. In this case, there is no substitute for adequate light and/or a fast lens and/or a smooth accurate tracking movement.
As another comment, deconvolution requires a very accurate approximation of the true convolution kernel, which may be provided by the motion sensors. However, to reconstruct the image without artifacts, the true kernel must not approach zero in the Fourier domain below the Nyquist frequency of the intended reconstruction (which is limited by the antialias filter in front of the Bayer mask). In fact, if the kernel's Fourier transform has too small a magnitude at some frequency, the reconstruction at that frequency will be essentially noise, or will be zero if adequate regularization is used. If the motion blur is more than a few pixels, this will generally mean that the reconstructed image will have an abridged spectrum in the direction of blur, compared to directions in which no blur occurred. Of course, if your hand is so shaky and the exposure so long that blur occurs in all directions, then the spectrum of the reconstructed image will be more uniform. It is likely to be truncated compared to the spectrum of an image taken without motion blur.
The quality of the reconstructed image would also be limited by the effects of other convolutions in the optical pathway. For instance, if you're using a cheap superzoom lens, don't expect to get anywhere near the antialias filter's Nyquist frequency in the final image, as the lens will have buggered up the details nonlinearly across the image even before the motion blur is added. If you're using nice lenses (Canon "L" series or Pentax "*" series and suchlike), then this will not be an issue.
The method would seem to be useful in low-ish light photography of stationary objects. A sober photographer would beat a drunk photographer at this, but the technique would help both to some extent. A photographer using a tripod would do best, of course.
Those who can make you believe absurdities can make you commit atrocities. - Voltaire
It's worth noting that page nine of the Frankencamera team's paper mentions the work of Joshi et al when it discusses deblurring pictures. Neel Joshi was the lead researcher from the article we are discussing.