how can change the angle of image ?

Hi everyone I have image I want change the angle of this image to be horizontal how can I do it? Thank you

Image example: http://up.arab-x.com/Apr12/Yen90992.jpg

Answer 1

[Thomas]

something like this? Based on the method shown here: http://stackoverflow.com/questions/5770818/how-to-align-image-matlab

I = imread('http://up.arab-x.com/Apr12/Yen90992.jpg');

%# egde detection
BW = edge(rgb2gray(I), 'canny');

%# hough transform
[H T R] = hough(BW);
P  = houghpeaks(H, 4, 'threshold',ceil(0.75*max(H(:))));
lines = houghlines(BW, T, R, P);

out = imrotate(I,lines(1).theta);

subplot(121)
imshow(I)
subplot(122)
imshow(out)

Answer 2

[Image Analyst]

Perhaps imrotate() or imtransform()?

[M.aM]

Yep I used this but what if I want rote the image with out known the angle Thanks Image Analyst :)

[Ryan]

I would tackle it with this strategy:

1. Find the top-most black pixel (in this case your upper left corner).
2. Find the right-most black pixel (in this case your upper right corner).
3. Use the change in width and height, along with trig to find the angle of rotation (it's like a triangle)

This strategy can be adapted to handle rotation the other way as well, but will not work past an 89 degree rotation in either direction.