Bug with conv2

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Nick Cooper
Nick Cooper on 24 Oct 2019
Answered: Bruno Luong on 30 Oct 2019
Here is a sample convolution performed with the built in function conv2. Unless I am completely crazy, this is not even close to the correct answer? Based on that image and kernel, I was expecting the output to be: [3 5 4; 9 0 6; 1 7 3]. Does anyone know of issues with conv2, or have insight to share?

Accepted Answer

Ajay Pattassery
Ajay Pattassery on 30 Oct 2019
Edited: Ajay Pattassery on 30 Oct 2019
The above output from conv2 with the argument as 'valid' is expected.
If you are computing in the paper the kernel needs to be flipped and then slid over the image I.
The resultant kernel will be
0 0 0
0 0 0
0 0 1
Then the output will be,
3 7 8
7 2 9
3 8 0

More Answers (1)

Bruno Luong
Bruno Luong on 30 Oct 2019
The answer is correct. May be you expect the result with sliding sum with unflip kernel which is of course wrong.

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