The whole question of lens sharpness...

Started Jun 12, 2013 | Discussions thread
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Alphoid Veteran Member • Posts: 3,802
Counterexample

olliess wrote:

Detail Man wrote:

olliess wrote:

Compare the heat/diffusion kernel to the (model) blur function of a lens.

Could you please state (or reference using URLs) both specific models of which you speak ?

A basic textbook on differential equations would be relevant here. If wiki counts you can look under "Fundamental Solutions" in Heat equation. You can also look at Fick's laws for diffusion. Then compare to the link given for Deconvolution.

There is no such thing as a 'diffusion-type process.' The blur of a lens is simply a convolution with the PSF of the lens. If the PSF is exactly known, it can be exactly inverted with a deconvolution.

So what is a "diffusion-type process" ?

One that resembles diffusion in a mathematical sense.

If you believe lens blur "resembles diffusion in a mathematical sense," can you please give a diffusion process, as per the links you gave, which has a PSF which is a solid octagon? It is trivial to design an optical system with this (I'll use your made-up terminology here for humor value) "blur function."

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