Just FYI, a visual simulation of the \"hard frequency cutoff\" effect of diffraction.
First, the un-diffracted image:
adding diffraction:
note how detail frequencies below the cutoff (about halfway across the image) are undisturbed, but those above are completely destroyed (replaced with a bit of ringing/spurious detail at the cutoff frequency).
Also for comparison, gaussian blur, with a gradual rather than hard cutoff of high frequencies:
And blurring by a circular point spread, which completely wipes out certain frequencies and lets others through:
(the acute observer might notice that between alternate frequency zeros, the position of white and black stripes has been reversed from the original.)
Mar 23, 2012 at 07:08 PM
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