How to flip my image

I have an image that I must flip using a nested for loop to flip the image vertically and horizontally, I have written a code that I think works but there is something wrong with it that it isn't. What have I done wrong?

%make 2d arrays values
imageData=imread('image.png');
[row, column] =size(imageData)
newImage=[]
%Use nested loops to change image mirrored
for i=[row:-1:1];
    for j=[column:-1:1];
    transposedMatrix(column, row) = imageData(i,j);
    transposedMatrix
    end
    
   
end

imshow(transposedMatrix)

[Adam]

Why do you have to use a nested for loop rather than just the standard flip functions?

column and row are constant scalars in that code so assigning to

transposedMatrix( column, row )

in a loop doesn't make sense. Maybe you mean j, i instead?

[Jesse Schultz]

It was asked to make a nested for loop, when I put j,i istead it rotated the image 90degrees, but it needs to be rotated 180. This is what ive been struggling with

[Joel Handy]

Well that invalidates my answer. Does the image need to be rotated or flipped. There is a difference.

[Jesse Schultz]

flipped both vertically and horizontally

[Adam]

Well, a flip instruction would be more like exchanging position i with row - i and j with column - j

Answer 1

[Joel Handy]

The are a few problems with your code. First, if you want the image, you dont want to transpose. That will flip and rotate, As adam has pointed out, column and row, you arent actuall transposing anyway. A better and correct way to transpose is to use permute.

imageData=imread('image.png');
newImage = permute(imageData, [2 1 3]);
imshow(newImage);

To actually flip, you should be able to use the flip function

imageData=imread('image.png');
newImage = flip(imageData,1);
newImage = flip(newImage,2);
imshow(newImage);

[Jesse Schultz]

I would do it like this, but its been asked if I can write it with nested for loops, so I can't use the flip function

[Joel Handy]

I that case . . .

%make 2d arrays values
imageData=imread('image.png');
[row, column] = size(imageData);
%Use nested loops to change image mirrored
for i=[1:row]
    for j=[1:column]
        newImage((row-i)+1, (column-j)+1) = imageData(i,j);
    end   
end
imshow(newImage)

You dont want to transpose rows and colums, you want to flip the the indexes within rows and columns.

[Jesse Schultz]

Thats exactly what I was doing wrong, thankyou!

[Witek Jachimczyk]

An example of image flipping and rotation:

>> img=imread("peppers.png");

>> montage({img,fliplr(img),flipud(img),rot90(img)})