grouping the pixel pairs

I have the code for grouping the pair of pixel. The code executed correctly. Please help me to reverse the same to get the original pixel matrix of the image

%grouping the pixel pairs
img=imread('cameraman.tif');
[rows,cols]=size(img);
[x,y]=ndgrid(1:rows,1:2:cols);
ind=sub2ind(size(img),x,y);
ind_shift=sub2ind(size(img),x,y+1);
pixels1=img(ind);
pixels2=img(ind_shift);
pixels=[pixels1(:) pixels2(:)];
[row1,cols1]=size(pixels);

Answer 1

[Image Analyst]

The function to reverse sub2ind() is called ind2sub(). Give it a try yourself first.

[Image Analyst]

By the way, attached is an example where I scramble an image matrix, in case you might be interested.