How to rotate an image in Matlab

For my class project I have to create an app which loads an image and allows you to change Red, blue, green colors and the brightness. I have sucessfully coded this app. Now I have to add a button which would allow me to rotate the image 90 degrees each time. The requirements is that I do not use any pre existing matlab functions, but have to create my own.

Would greatly appreciate any help on this. Thank you.

Answer 1

[J Chen]

You basically read the image into a matrix, then change the array element to a different location (swich row to column, etc.)

[Emir Mulic]

How would i store the image into an empty matrix. And then would I use some matrix transpose function ?

Answer 2

[ac_bm_mat]

A = imread('ngc6543a.jpg');

You may use imread to read an image to a matrix.

Then operating with A matrix can give you 90 degree rotated image.

Answer 3

[yanqi liu]

yes，sir，may be rot90，such as

im = imread('football.jpg');
for i = 1 : 4
    im = rot90(im, 1);
    figure; imshow(im, []);
end

[Image Analyst]

rot90 is a built in function, which he is not allowed to use.

Answer 4

[Image Analyst]

You can use the apostrophe operator '

yourImage = yourImage';

This transposes the matrix. To now get a mirror image you have to swap rows or columns.

You can use the rotation matrix: https://en.wikipedia.org/wiki/Rotation_matrix