function [xs, ys] = extractData(I)
% takes an image as input and outputs the two dominant vanishing points
% I  = imread('kickoff.jpg');
% returns angles in radians


I = mean(I,3);
xs = [];
ys = [];
% edge detection (convolution with grad operator and threshold)
BW = edge(I,'canny');
[h,w] = size(BW);
for i=1:h,
    for j=1:w;
        if BW(i,j) == 1
            xs = [xs j];
            ys = [ys h-i];
        end
    end
end
