if true
function imP = ImToPolar (imR, rMin, rMax, M, N)
% IMTOPOLAR converts rectangular image to polar form. The output image is
% an MxN image with M points along the r axis and N points along the theta
% axis. The origin of the image is assumed to be at the center of the given
% image. The image is assumed to be grayscale.
% Bilinear interpolation is used to interpolate between points not exactly
% in the image.
%
% rMin and rMax should be between 0 and 1 and rMin < rMax. r = 0 is the
% center of the image and r = 1 is half the width or height of the image.
%
% V0.1 7 Dec 2007 (Created), Prakash Manandhar pmanandhar@umassd.edu
[Mr Nr] = size(imR); % size of rectangular image Om = (Mr+1)/2; % co-ordinates of the center of the image On = (Nr+1)/2; sx = (Mr-1)/2; % scale factors sy = (Nr-1)/2;
imP = zeros(M, N);
delR = (rMax - rMin)/(M-1); delT = 2*pi/N;
% loop in radius and for ri = 1:M for ti = 1:N r = rMin + (ri - 1)*delR; t = (ti - 1)*delT; x = r*cos(t); y = r*sin(t); xR = x*sx + Om; yR = y*sy + On; imP (ri, ti) = interpolate (imR, xR, yR); end end
function v = interpolate (imR, xR, yR) xf = floor(xR); xc = ceil(xR); yf = floor(yR); yc = ceil(yR); if xf == xc & yc == yf v = imR (xc, yc); elseif xf == xc v = imR (xf, yf) + (yR - yf)*(imR (xf, yc) - imR (xf, yf)); elseif yf == yc v = imR (xf, yf) + (xR - xf)*(imR (xc, yf) - imR (xf, yf)); else A = [ xf yf xf*yf 1 xf yc xf*yc 1 xc yf xc*yf 1 xc yc xc*yc 1 ]; r = [ imR(xf, yf) imR(xf, yc) imR(xc, yf) imR(xc, yc) ]; a = A\double(r); w = [xR yR xR*yR 1]; v = w*a; end
end
