find corners of object in image using sobel operator and canny in matlab

To find the corners of an object in an image using Sobel operator and Canny algorithm, you first need to perform edge detection using Sobel and then apply Canny to detect the corners. Here's how to do it in MATLAB:

main.m
% Read the image
img = imread('image.jpg');

% Convert the image to grayscale
gray = rgb2gray(img);

% Apply Sobel operator to detect edges
sobelX = [-1 0 1 ; -2 0 2 ; -1 0 1];
sobelY = sobelX';
edgeX = filter2(sobelX, gray);
edgeY = filter2(sobelY, gray);
edgeImg = sqrt(edgeX .^ 2 + edgeY .^ 2);

% Apply Canny to detect corners
cornersImg = corner(edgeImg);

% Display the image with corners
imshow(img), hold on
plot(cornersImg(:,1), cornersImg(:,2), 'r*');
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In the code above, we first read the image and convert it to grayscale. Then we apply the Sobel operator to detect edges in the image. We apply the operator in the X and Y directions, and then combine the results to get the final edge image. Next, we apply Canny to detect corners in the edge image. Finally, we display the original image with red marks on the corners detected by Canny.

Note that the threshold value used by Canny algorithm can be adjusted to improve the quality of corner detection.