使用霍夫变换画出的轮廓比原始图形大很多，请问这是什么原因？
img_actural = imread("C:\Users\cip\Desktop\fivesquare.jpg");
img = rgb2gray(img_actural);
img_edge = edge(img, "canny");
figure(1), imshow(img_edge), title("canny");
%apply Hough transform to find candidate line
[accum theta rho] = hough(img_edge);
figure(2), imshow(accum, [], "XData", theta, "YData", rho), title("hough accumlator");
xlabel('\theta'), ylabel('\rho');
axis on, axis normal, hold on, hold off;
%find peaks in the Hough accmulator matrix
peaks = houghpeaks(accum, 100, "Threshold", ceil(0.56 * max(accum(:))), "NHoodSize", [5 5]);
hold on, plot(theta(peaks( :, 2)), rho(peaks(:,1)), "rs"), hold off;
%find lines segments in the image
line_seg = houghlines(img, theta, rho, peaks, "Fillgap", 50, "Minlength", 100);
figure(3), imshow(img_actural), title("line segments");
hold on;
for k = 1 : length(line_seg)
end_points = [line_seg(k).point1; line_seg(k).point2];
% Plot beginnings and ends of lines
plot(end_points(1,1), end_points(1,2),'x','LineWidth',2,'Color','yellow');
plot(end_points(2,1),end_points(2,2),'x','LineWidth',2,'Color','red');
plot(end_points(:, 1), end_points(:, 2), "LineWidth", 2, "Color", "green");
end
hold off;
