weighted_F.m

function [Q]= WFb(FG,GT)
% WFb Compute the Weighted F-beta measure (as proposed in "How to Evaluate
% Foreground Maps?" [Margolin et. al - CVPR'14])
% Usage:
% Q = FbW(FG,GT)
% Input:
%   FG - Binary/Non binary foreground map with values in the range [0 1]. Type: double.
%   GT - Binary ground truth. Type: logical.
% Output:
%   Q - The Weighted F-beta score

%Check input
if (~isa( FG, 'double' ))
    error('FG should be of type: double');
end
if ((max(FG(:))>1) || min(FG(:))<0)
    error('FG should be in the range of [0 1]');
end
if (~islogical(GT))
    error('GT should be of type: logical');
end

dGT = double(GT); %Use double for computations.


E = abs(FG-dGT);
% [Ef, Et, Er] = deal(abs(FG-GT));

[Dst,IDXT] = bwdist(dGT);
%Pixel dependency
K = fspecial('gaussian',7,5);
Et = E;
Et(~GT)=Et(IDXT(~GT)); %To deal correctly with the edges of the foreground region
EA = imfilter(Et,K);
MIN_E_EA = E;
MIN_E_EA(GT & EA<E) = EA(GT & EA<E);
%Pixel importance
B = ones(size(GT));
B(~GT) = 2-1*exp(log(1-0.5)/5.*Dst(~GT));
Ew = MIN_E_EA.*B;

TPw = sum(dGT(:)) - sum(sum(Ew(GT))); 
FPw = sum(sum(Ew(~GT)));

R = 1- mean2(Ew(GT)); %Weighed Recall
P = TPw./(eps+TPw+FPw); %Weighted Precision

Q = (2)*(R*P)./(eps+R+P); %Beta=1;
% Q = (1+Beta^2)*(R*P)./(eps+R+(Beta.*P));
end