Hello,
I had the same problem and this was the first Google search result, so for anyone who finds this:
Instead of doing this:
allImages(:,:,:,1) = image;
montage(allImages, 'Size', [3, 3]);
Which will display a 3x3 matrix with the first row displaying the red, green and blue channels separately, do this:
allImages{1,1} = image;
montage(allImages, 'Size', [3, 3]);
Which will display the image in the top left corner in RGB.