MATLAB hough

The Hough transform in MATLAB is a popular technique used for detecting straight lines and curves in images. The MATLAB function `hough` takes an input binary image and returns a Hough transform matrix that represents the presence of lines in the image.

The syntax for `hough` is as follows:

[H,theta,rho] = hough(BW)

where `BW` is the binary image, `H` is the Hough transform matrix, `theta` is the vector of theta values (in degrees) used in the transform, and `rho` is the vector of rho values used in the transform.

Once the Hough transform matrix is obtained, the `houghpeaks` function can be used to identify peaks in the matrix, which correspond to lines in the image. The `houghlines` function can then be used to extract the parameters of these lines (i.e., their slope and intercept) and draw them on the original image.

Here's an example code snippet that demonstrates the use of the Hough transform and related functions in MATLAB:

% Read in an image
I = imread('coins.png');

% Convert to binary
BW = imbinarize(I);

% Apply the Hough transform
[H,theta,rho] = hough(BW);

% Find peaks in the Hough transform matrix
peaks = houghpeaks(H, 5);

% Extract the parameters of the lines corresponding to the peaks
lines = houghlines(BW,theta,rho,peaks);

% Draw the lines on the original image
figure, imshow(I), hold on
for k = 1:length(lines)
   xy = [lines(k).point1; lines(k).point2];
   plot(xy(:,1),xy(:,2),'LineWidth',2,'Color','green');
end

This code reads in an image of some coins, converts it to binary, applies the Hough transform, finds the peaks in the Hough transform matrix, extracts the parameters of the lines corresponding to those peaks, and draws those lines on the original image. The result is an image with green lines overlaid on top of the coins, indicating the presence of straight edges in the image.