function pcimg=imgpolarcoord(img,radius,angle)
% IMGPOLARCOORD converts a given image from cartesian coordinates to polar
% coordinates.
%
% Input:
% img : bidimensional image.
% radius : radius length (# of pixels to be considered).
% angle : # of angles to be considered for decomposition.
%
% Output:
% pcimg : polar coordinate image.
%
% Usage Example:
% im=double(imread('cameraman.tif'));
% fim=fft2(im);
% pcimg=iapolarcoord(im);
% fpcimg=iapolarcoord(fim);
% figure; subplot(2,2,1); imagesc(im); colormap gray; axis image;
% title('Input image'); subplot(2,2,2);
% imagesc(log(abs(fftshift(fim)+1))); colormap gray; axis image;
% title('FFT');subplot(2,2,3); imagesc(pcimg); colormap gray; axis image;
% title('Polar Input image'); subplot(2,2,4);
% imagesc(log(abs(fpcimg)+1)); colormap gray; axis image;
% title('Polar FFT');
%
% Notes:
% The software is provided "as is", without warranty of any kind.
% Javier Montoya would like to thank prof. Juan Carlos Gutierrez for his
% support and suggestions, while studying polar-coordinates.
% Authors: Juan Carlos Gutierrez & Javier Montoya.
if nargin < 1
error('Please specify an image!');
end
img = double(img);
[rows,cols] = size(img);
cy = round(rows/2);
cx = round(cols/2);
if exist('radius','var') == 0
radius = min(round(rows/2),round(cols/2))-1;
end
if exist('angle','var') == 0
angle = 360;
end
pcimg = [];
i = 1;
for r=0:radius
j = 1;
for a=0:2*pi/angle:2*pi-2*pi/angle
pcimg(i,j) = img(cy+round(r*sin(a)),cx+round(r*cos(a)));
j = j + 1;
end
i = i + 1;
end
end
