Moiré No More - Hackdot

Re:Moiré No More by DrNosferatu on Wednesday January 04, 2023 @12:55PM (#34248951)

Done since the mid-1960's :) but, nevertheless, always an interesting read!

This is classical (as in pre-GPU AI/ML) Image Processing. The reference text book in the field, "Digital Image Processing" by Gonzalez et al, shows how to do it: like the pioneers at JPL's Image Processing Laboratory (est. 1965) denoised Mars pictures from the Mariner probes using Frequency Domain methods like the posted article uses - see an example below.

[https://pixelcraft.photo.blog/2021/09/29/the-early-days-of-i...]

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Re:Moiré No More by DrNosferatu on Wednesday January 04, 2023 @01:01PM (#34249044)

Speaking of which, with the advent of AI/ML methods, how are Image Processing and Machine Vision courses taught today at Universities?

- Has Python or other free languages replaced Matlab yet?

- Is Gonzales' course structure still followed somehow?

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Re:Moiré No More by jbay808 on Wednesday January 04, 2023 @03:06PM (#34250676)

It's so classical, it can be done without a digital computer at all, using fourier optics! The true fastest fourier transform, done at the speed of light.

https://en.wikipedia.org/wiki/Fourier_optics

At the focal plane of a lens, an image is converted into its spatial fourier components. By adding blocking elements at that focal plane (eg. an aperture, or a piece of glass with marker dots), unwanted frequency components can be cut out from the image.

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Re:Moiré No More by DrNosferatu on Wednesday January 04, 2023 @03:23PM (#34250922)

Aha - very nice!

My background with Fourier optics is mostly theoretical and the applications numerical.

But what references (books or online) exist about physical applications, like the one you mention?

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