Now that we have the lens Point Spread Function it should be straight forward to reverse its blurring effect out of the image, right?
Tag Archives: fft
The Units of Discrete Fourier Transforms
This article is about specifying the units of the Discrete Fourier Transform of an image and the various ways that they can be expressed. This apparently simple task can be fiendishly unintuitive.
The image we will use as an example is the familiar Airy Pattern from the last few posts, at f/16 with light of mean 530nm wavelength. Zoomed in to the left in Figure 1; and as it looks in its 1024×1024 sample image to the right:
A Simple Model for Sharpness in Digital Cameras – Diffraction and Pixel Aperture
Now that we know from the introductory article that the spatial frequency response of a typical perfect digital camera and lens (its Modulation Transfer Function) can be modeled simply as the product of the Fourier Transform of the Point Spread Function of the lens and pixel aperture, convolved with a Dirac delta grid at cycles-per-pixel pitch spacing
(1)
we can take a closer look at each of those components ( here indicating normalization to one at the origin). I used Matlab to generate the examples below but you can easily do the same with a spreadsheet. Continue reading A Simple Model for Sharpness in Digital Cameras – Diffraction and Pixel Aperture