What is the inverse of a filter?

Dear all,

I have a gray intensity image, I, and let's say I applied a mean filter to it of size 3

Meanfilt = filter2(fspecial('average',3),I)/255;

My question is how to return the image back from Meanfilt ----> I ? Is there any inverse functions in matlab?

Thank you.

Meshoo

Answer 1

[Walter Roberson]

http://www.mathworks.com/matlabcentral/answers/42575-how-can-i-deblur-an-image-given-the-original-psf

For the averaging filter there is also a way to do it by solving systems of linear equations; I think the logic should extend to anything constructed using conv2() but I would need to think more to check. It involves creating an (R*C) x (R*C) matrix of weights, which could get rather large. I do not know how efficient it would be.

[Meshooo]

OK, thank you very much.

Answer 2

[Image Analyst]

Well there is such a thing as an inverse filter, though it has problems in real world implementations because the noise can wreak havoc. So they've invented better methods that are more robust and better in the presence of noise. Look up the help on wiener2() and deconvlucy().

[Meshooo]

Thank you very much.