Boundcon.m

%  CORRESPONDENCE INFORMATION
%  This code is written by Gaofeng MENG 
%
%  Gaofeng MENG:  
%  National Laboratory of Pattern Recognition,
%  Institute of Automation, Academy of Sciences, Beijing 100190
%  Comments and bug reports are welcome.  Email to gfmeng@nlpr.ia.ac.cn
%
%  WORK SETTING:
%  This code has been compiled and tested by using MATLAB R2009a
%
%  For more detials, please see our paper:
%  Gaofeng MENG, Ying WANG, Jiangyong DUAN, Shiming XIANG, Chunhong PAN. 
%  Efficient Image Dehazing with Boundary Constraint and Contextual Regularization, 
%  ICCV, Sydney, Australia, pp.617-624, 3-6 Dec., 2013.
%
%  Last Modified: Feb. 14, 2014, By Gaofeng MENG
%   

function [t_bdcon, t_b] = Boundcon(HazeImg, A, C0, C1, sz)
% patch-wise transmission from boundary constraint

if length(A) == 1
    A = A * ones(3, 1);
end
if length(C0) == 1
    C0 = C0 * ones(3, 1);
end
if length(C1) == 1
    C1 = C1 * ones(3, 1);
end
HazeImg = double(HazeImg);

% pixel-wise boundary
t_r = max((A(1) - HazeImg(:, :, 1)) ./ (A(1)  -  C0(1)), (HazeImg(:, :, 1) - A(1)) ./ (C1(1) - A(1) ));
t_g = max((A(2) - HazeImg(:, :, 2)) ./ (A(2)  - C0(2)), (HazeImg(:, :, 2) - A(2)) ./ (C1(2) - A(2) ));
t_b = max((A(3) - HazeImg(:, :, 3)) ./ (A(3)  - C0(3)), (HazeImg(:, :, 3) - A(3)) ./ (C1(3) - A(3) ));
t_b = max(cat(3, t_r, t_g, t_b), [], 3);
t_b = min(t_b, 1);

% minimum filtering
se = strel('square', sz);
t_bdcon = imclose(t_b, se);