How to find the indices of the closest value in two non-equal sized matrices?

I have two matrices with random numbers. One is 768 by 1024 (matrix A) and the other is 1536 by 2048 (matrix B). I want to develope a for loop code of some sort that is able to loop over all the numbers in those matrices and tell me what are the indices in matrix B that corresponds to the closest value in matrix A, and does this for ALL the numbers. I attempted this and failled, I hope someone can help. Thanks in advance.

Note: I uploaded an example of the two matrices that I was given.

Answer 1

[KSSV]

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