draw freddy mercury in matlab

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

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

% Apply Canny edge detection to identify the edges
edges = edge(gray, 'Canny');

% Apply Hough transform to detect the lines in the edge map
[H,theta,rho] = hough(edges);
P = houghpeaks(H,10,'threshold',ceil(0.3*max(H(:))));
lines = houghlines(edges,theta,rho,P,'FillGap',5,'MinLength',7);

% Group the lines into larger objects
objects = {};
for i = 1:length(lines)
    obj = [];
    for j = 1:length(lines)
        if i ~= j && isclose(lines(i), lines(j))
            obj = [obj j];
        end
    end
    obj = sort([obj i]);
    obj_str = sprintf('%d', obj);
    if ~ismember(obj_str, objects)
        objects{end+1} = obj_str;
    end
end

% Draw the detected objects
figure; imshow(img); hold on;
for i = 1:length(objects)
    obj_str = objects{i};
    for j = 1:length(obj_str)
        k = str2num(obj_str(j));
        xy = [lines(k).point1; lines(k).point2];
        plot(xy(:,1), xy(:,2), 'LineWidth', 2, 'Color', 'green');
    end
    xy = get_object_bbox(lines(str2num(obj_str)), size(img));
    rectangle('Position', xy, 'EdgeColor', 'red', 'LineWidth', 2);
end

% Helper function to check if lines are close to each other
function out = isclose(line1, line2)
    out = false;
    dtheta = abs(line1.theta - line2.theta);
    drho = abs(line1.rho - line2.rho);
    if dtheta < 5 && drho < 50
        out = true;
    end
end

% Helper function to compute the bounding box of an object
function out = get_object_bbox(lines, img_size)
    x = [];
    y = [];
    for i = 1:length(lines)
        xy = [lines(i).point1; lines(i).point2];
        x = [x; xy(:,1)];
        y = [y; xy(:,2)];
    end
    xmin = max(min(x) - 10, 1);
    xmax = min(max(x) + 10, img_size(2));
    ymin = max(min(y) - 10, 1);
    ymax = min(max(y) + 10, img_size(1));
    out = [xmin ymin (xmax-xmin) (ymax-ymin)];
end
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