Submitted by so-gold t3_117npc4 in askscience
hatsune_aru t1_j9owuz6 wrote
Most of the people here are wrong. It is possible to un-blur an image within reasonable fidelity, provided that you know how the blur was done (i.e. which method, what the parameters for the method were, etc).
The naive way of blurring an image basically averages the input pixels from its neighbors and outputs it on the output. This is a reversible process, provided you know how the averaging window was created.
The averaging window can also be estimated to potentially get a "good enough" reproduction of the image before it was blurred.
loki130 t1_j9qm08v wrote
In the extreme case, if you take an entire image and average it to a single color, clearly you can't reconstruct any detail from that no matter how clearly you know the algorithm. I think a similar argument could be made that a large image split into 4 quadrants that are each completely averaged would also be unrecoverable. Perhaps there is some floor of smaller blur radius where the image becomes recoverable, but I don't think it's obvious that knowing the blur process always allows reversal.
hatsune_aru t1_j9qmunn wrote
I like to think of that extreme example as "edge effects". Obviously there are limitations to the recovery technique, but "deblurring" is absolutely a thing both in imaging and similarly in non-imaging applications.
https://en.wikipedia.org/wiki/Blind_deconvolution
In a sense, electronic engineering (which I can say I'm a specialist in) concepts like emphasis, equalization, etc are just compensations for channel effects, which one could think as time varying signal equivalents for blurring in imaging.
In that sense, recovery of a "blurred" signal via equalization is absolutely used everywhere that uses high speed digital signals like USB, DDR, PCIe, etc.
Viewing a single comment thread. View all comments