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How to flip my image

Asked by Jesse Schultz on 21 Aug 2019
Latest activity Commented on by Jesse Schultz on 21 Aug 2019
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)

  5 Comments

Joel Handy on 21 Aug 2019
Well that invalidates my answer. Does the image need to be rotated or flipped. There is a difference.
Jesse Schultz on 21 Aug 2019
flipped both vertically and horizontally
Adam
on 21 Aug 2019
Well, a flip instruction would be more like exchanging position i with row - i and j with column - j

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1 Answer

Answer by Joel Handy on 21 Aug 2019
Edited by Joel Handy on 21 Aug 2019
 Accepted Answer

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);

  3 Comments

Jesse Schultz on 21 Aug 2019
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 on 21 Aug 2019
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 on 21 Aug 2019
Thats exactly what I was doing wrong, thankyou!

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