drawEllipses.m

% Usage: plot_ellipses(Ellipses,size_im,fig_handle);
%
% Inputs: 
% Ellipses - parameters of the detected ellipses. Each coloumn contains
%                 [ x0 - x coordinate of the center of the ellipse
%                   y0 - y coordinate of the center of the ellipse
%                   a - length of semimajor axis
%                   b - length of semiminor axis
%                   alpha - angle of orientation of semimajor axis]
% size_im - size(im) where im is the gray image
% fig_handle - the handle of the figure if specified, if fig_handle=[] then
%                a new figure is created
%
% This function plots the ellipses
%
% Copyright (c) 2012 Dilip K. Prasad
% School of Computer Engineering
% Nanyang Technological University, Singapore
% http://www.ntu.edu.sg/


function [] = drawEllipses(ellipses_para,im)
if ~isempty(im)
figure;
%imshow(im); %show image
imshow(im,'border','tight','initialmagnification','fit'); %show image
size_im = size(im);
hold on;
else
    hold on;
end

th=0:pi/180:2*pi;
for i=1:size(ellipses_para,2)
    Semi_major= ellipses_para(3,i);
    Semi_minor= ellipses_para(4,i);
    x0= ellipses_para(1,i);
    y0= ellipses_para(2,i);
    Phi= ellipses_para(5,i);
    x=x0+Semi_major*cos(Phi)*cos(th)-Semi_minor*sin(Phi)*sin(th);
    y=y0+Semi_minor*cos(Phi)*sin(th)+Semi_major*sin(Phi)*cos(th);   
    
    plot(x,y,'r', 'LineWidth',2);
end
if ~isempty(im)
axis on; set(gca,'XTick',[],'YTick',[]);axis ij;axis equal;axis([0 size_im(2) 0 size_im(1)]);
end

end