function [ error_per_image ] = compute_error( ground_truth_all, detected_points_all )
%compute_error
% compute the average point-to-point Euclidean error normalized by the
% inter-ocular distance (measured as the Euclidean distance between the
% outer corners of the eyes)
%
% Inputs:
% grounth_truth_all, size: num_of_points x 2 x num_of_images
% detected_points_all, size: num_of_points x 2 x num_of_images
% Output:
% error_per_image, size: num_of_images x 1
num_of_images = size(ground_truth_all,3);
num_of_points = size(ground_truth_all,1);
error_per_image = zeros(num_of_images,1);
for i =1:num_of_images
detected_points = detected_points_all(:,:,i);
ground_truth_points = ground_truth_all(:,:,i);
if num_of_points == 68
interocular_distance = norm(ground_truth_points(37,:)-ground_truth_points(46,:));
elseif num_of_points == 51
interocular_distance = norm(ground_truth_points(20,:)-ground_truth_points(29,:));
end
sum=0;
for j=1:num_of_points
sum = sum+norm(detected_points(j,:)-ground_truth_points(j,:));
end
error_per_image(i) = sum/(num_of_points*interocular_distance);
end
end