Superimposing points, lines over image in Matlab

figure
imshow(img)
plot(x_c, y_c, '.');
line_x = [x_c - round(w_c/2), x_c + round(w_c/2), x_c + round(w_c/2), x_c - round(w_c/2), x_c - round(w_c/2)];
line_y = [y_c - round(h_c/2), y_c - round(h_c/2), y_c + round(h_c/2), y_c + round(h_c/2), y_c - round(h_c/2)];
line(line_x, line_y, 'LineWidth',1,'Color',[.8 .8 .8]);

Other reference