ifft2 on an asymmetric matrix does not work correctly?

I have a complex matrix of size 256x128. When I perform ifft2 the picture is folded across the y direction. The same ifft2 function works well on a symmetric matrix (128x128). Help

Answer 1

[David Young]

ifft2 works correctly.

You can demonstrate this with the following code

img = rgb2gray(imread('peppers.png'));   % example image
img = img(1:256, 1:128);                 % make it 256x128
img = double(img)/256;                   % double, scale to 0-1
imshow(img);                             % have a look
imgTrans = fft2(img);                    % transform
imgRestored = ifft2(imgTrans);           % inverse transform
figure; imshow(imgRestored);             % looks ok

There must be some other problem with the way you generate the 256x128 matrix.