How to get the original matrix back?

3 views (last 30 days)
Ammy
Ammy on 5 Dec 2021
Commented: Ammy on 5 Dec 2021
clc;clear all;close all
A=reshape (1:16 ,4,4); % 4x4 matrix
B1 = A(1:2:end, 1:2:end);
B2 = A(1:2:end, 2:2:end);
B3= A(2:2:end, 1:2:end);
B4 = A(2:2:end, 2:2:end);
c = reshape([B1 B2 B3 B4].', 4,4)';
c(:,[2,3]) = c(:,[3,2]) % swap columns
For the above the code works properly, but the problem is that I am unable to get orignal matrix back when I use
A=reshape (1:36 ,6,6); % 6x6 matrix
In other words how can I get back 'c' for large square matrix. Is there any generalized way that works for any square matrix.

Accepted Answer

DGM
DGM on 5 Dec 2021
Edited: DGM on 5 Dec 2021
This should work at least for even sized arrays. I'm sure there are other ways.
s = 8; % must be even
A = reshape (1:s^2 ,s,s);
B1 = A(1:2:end, 1:2:end);
B2 = A(1:2:end, 2:2:end);
B3 = A(2:2:end, 1:2:end);
B4 = A(2:2:end, 2:2:end);
c = reshape([B1 B2 B3 B4].',size(A)).'
c = permute(reshape(c,size(A,1),[],2),[1 3 2])
c = reshape(c,size(A))
When trying to "demosaic" an array with reshape(), it's helpful to split it into an extra dimension and permute.

More Answers (0)

Categories

Find more on Operating on Diagonal Matrices in Help Center and File Exchange

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!