Friday, September 14, 2012

Point Spread Function

What is point spread function? What does it have to do with image restoration, clarification, or enhancement?

For the purposes of those arriving here from a Bing search looking for spread functions, PSF is not a type of gambling where the point spread is essentially a handicap towards the underdog. Thus the wager becomes "Will the favorite win by more than the point spread?" The point spread can be moved to any level to create an equal number of participants on each side of the wager. PSF is not a way to make money gambling.

Remember that image restoration refers to the removal or minimization of known degradations in an image. This includes deblurring of images degraded by the limitations of the sensor or its environment, noise filtering, and correction of geometric distortions or non-linearities due to sensors. The point spread function describes the imaging system's response to a point input. A point input, represented as a single pixel in the “ideal” image, will be reproduced as something other than a single pixel in the “real” image.

So, in essence, a PSF deals with a point that spreads. A point that spreads is essentially what happens when you think of blur (motion blur, camera shake, etc). The effect of motion blur transforms points into lines. Therefore, we have to find in the image a line that originally should had been a point and in the photo came up as a line.

I'll illustrate how to fix the problem of motion blur soon. But for now, I just wanted to introduce the idea of PSF.


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