How to shuffle an image diagonally?

I need to shuffle an image of size 256x256x3 along diagonally. That is the pixel value of upper left corner must come at the lower right corner and all the pixels at the corresponding position in the other half. Please help me with that code

Answer 1

[Guillaume]

Sounds like a 180 rotation, so:

rot90(yourimage, 2)

Answer 2

[Jan]

This can be either a rotation or a mirroring. A rotation works either by rot90 (see Guillaume's answer), or by:

s    = size(img)
img2 = img(s(1):-1:1, s(2):-1:1, :);

The mirroring needs just an additional transposition of the first two dimensions:

img2 = permute(img(s(1):-1:1, s(2):-1:1, :), [2,1,3]);