Im trying to slice an image and switch its quadrants so that I switch the bottom right quadrant and the top left quadrant and the bottom left quadrant with the top right quad

function sliceNDice(fn)
img = imread(fn);
imshow(fn)
figure
topLeft = img(1:end/2,1:end/2);
topRight = img(1:end/2,end/2+1:end);
botLeft = img(end/2+1:end,1:end/2);
botRight = img(end/2+1:end,end/2+1:end);
newImg = img(3,botRight,botLeft,topRight,topLeft);
imgshow(newImg)
end

Answer 1

[Walter Roberson]

newImg = img(3,botRight,botLeft,topRight,topLeft);

That would try to index the array img using 3 as the row index, using the entire array botRight as the column indices, using the entire array botLeft as the plane index, and up through the hyper dimensions.

You should be using

newImg = cat(2,botRight,botLeft,topRight,topLeft);

Answer 2

[DGM]

img = imread('peppers.png');

topLeft = img(1:end/2,1:end/2,:); % specify enough dimensions
topRight = img(1:end/2,end/2+1:end,:);
botLeft = img(end/2+1:end,1:end/2,:);
botRight = img(end/2+1:end,end/2+1:end,:);
newImg = [botRight,botLeft; topRight,topLeft]; % concatenate

imshow(newImg)

Note that the output image size only matches that of the input image if the input image has even geometry.

FWIW, if you were using MIMT, this reduces to one line.

outpict = shuffle(inpict,[2 2],[4 3 2 1]);