## Copyright (C) 2020 Jens
## 
## This program is free software: you can redistribute it and/or modify it
## under the terms of the GNU General Public License as published by
## the Free Software Foundation, either version 3 of the License, or
## (at your option) any later version.
## 
## This program is distributed in the hope that it will be useful, but
## WITHOUT ANY WARRANTY; without even the implied warranty of
## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
## GNU General Public License for more details.
## 
## You should have received a copy of the GNU General Public License
## along with this program.  If not, see
## <https://www.gnu.org/licenses/>.

## -*- texinfo -*- 
## @deftypefn {} {@var{retval} =} bluescreen (@var{input1}, @var{input2})
##
## @seealso{}
## @end deftypefn

## Author: Jens <jens@orion>
## Created: 2020-10-03

function chromakey (img_name)
im = im2double(imread(img_name));
im_rgb = imresize(im, 1);
se = strel('square',3)

#ref_rgb = toRef([0.3 0.4 0.65], size(im_rgb));
ref_rgb = toRef([0.2 0.6 0.95], size(im_rgb));

k_ds = 0.2;
k_c_matte = 1.0
k_e_matte = 3

k_c_edge = 3.0
k_e_edge = 3.0

close all;

figure;
imshow(ref_rgb);

figure;
matte = min(1, k_c_matte*similarity_rgb(im_rgb, ref_rgb, k_e_matte));
#matte = mask_clip_below(matte, 0.5);
imshow(matte); title("matte")

figure;
final = max(0, im_rgb - k_ds*matte.*ref_rgb).*matte;
imshow(final); title("final")

figure;
edges = k_c_edge*coloredges(final, ref_rgb, k_e_edge);
#edges = mask_clip_below(edges, 0.25);
imshow(edges); title("edges")

figure;
final_cc = im_rgb - edges.*ref_rgb;
imshow(final_cc); title("final_cc")

imwrite(final, 'final.png','png','alpha', matte);
imwrite(final_cc, 'final_cc.png','png','alpha', matte);
imwrite(matte, 'alpha.png','png');

function r = toRef(ref, d)
	r = repmat(reshape(ref,1, 1, 3), d(1), d(2));
endfunction

function s = similarity_rgb(im, ref, k)
	s = 1-exp(-k*vecnorm (im - ref, 2, 3));
endfunction

function s = coloredges(im, ref, k)
	s = exp(-k*vecnorm (im - ref, 2, 3));
endfunction

function mask = mask_clip_above(mask_in, thresh)
		k = mask_in < thresh;
		mask = k .* mask_in + kn;
endfunction

function mask = mask_clip_below(mask_in, thresh)
		k = mask_in > thresh;
		mask = k .* mask_in  + 0;
endfunction

endfunction