- added matlab scripts

chromakey/alpha_gen.m

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+## 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} =} alpha_gen (@var{input1}, @var{input2})
+##
+## @seealso{}
+## @end deftypefn
+
+## Author: Jens <jens@orion>
+## Created: 2020-10-07
+
+function a = alpha_gen(N, slope)
+s = (0:N-1)/(N-1);
+a = to_param(s, 0, 1, 2, -slope, 0.5, 0.5);
+
+color_bg = [0.1 0.3 0.9];
+color_fg = [0.9 0.9 0.0];
+
+mean_fg  = mean(color_fg)
+norm_fg = norm(color_fg)
+mean_bg  = mean(color_bg)
+norm_bg = norm(color_bg)
+
+w = N;
+h = 8;
+
+im_a = repmat(a, h, 1);
+
+
+im_comp = to_im (color_fg, a, h) + to_im (color_bg, 1-a, h);
+im_fg = to_ref(color_fg, size(im_comp));
+im_bg = to_ref(color_bg, size(im_comp));
+
+im_ac = (im_comp - im_bg)./(im_fg - im_bg);
+
+close all;
+figure;
+imshow(im_a); title ("im_a")
+
+figure;
+imshow(im_ac); title ("im_ac")
+
+figure;
+imshow(im_comp); title ("im_comp")
+
+figure;
+im_filtered = im_comp - to_ref(color_bg, size(im_comp));
+imshow(im_filtered);  title ("im_filtered")
+
+strip = im_filtered(1,:,:);
+strip_clamped = max(0, strip);
+strip_clamped_norm = strip_clamped;
+n = vecnorm(strip, 2, 3)/norm_fg;
+figure;
+plot (s, a, s, n); grid; legend("Ground truth", "Calculated")
+
+endfunction
+
+function im = to_im(color, a, h)
+w = length(a);	
+im = reshape([color(1)*ones(h,1)*a color(2)*ones(h,1)*a color(3)*ones(h,1)*a], h, w, 3);
+ 
+endfunction
+
+function r = to_ref(ref, d)
+	r = repmat(reshape(ref,1, 1, 3), d(1), d(2));
+endfunction

chromakey/eval_matte.m

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+## 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
+
+# chromakey('adventure_rose', 20, 10)
+# chromakey('cineon_before', 200, 100)
+
+function eval_matte (prj_name, k_e_matte)
+
+clip_white_thresh = 0.80;
+clip_white_amp = 3;
+
+clip_black_thresh = 0.20;
+clip_black_amp = 3;
+
+[im_rgb, ref_rgb] = prj_load(prj_name);
+
+close all;
+
+pre_filtered = im_rgb - ref_rgb;
+pre_filtered_p = max(0,pre_filtered);
+pre_filtered_n = -min(0,pre_filtered);
+
+figure;
+imshow(abs(pre_filtered)); title("pre_filtered")
+
+figure;
+filtered_var = var(pre_filtered, 0, 3);
+
+kn = 1/max(max(filtered_var(:)))
+var_n = k_e_matte*kn*filtered_var;
+matte = min(1, var_n);
+imshow(matte); title("var")
+
+figure;
+filtered_norm = vecnorm(pre_filtered, 2, 3);
+imshow(filtered_norm); title("norm")
+
+figure;
+intermediate = im_rgb.*matte;
+imshow(intermediate); title("intermediate")
+
+figure;
+edges = exp(-1.7*k_e_matte*var(intermediate - ref_rgb, 0, 3));
+imshow(edges); title("edges")
+
+figure;
+final = intermediate - edges.*ref_rgb;
+imshow(final); title("final")
+
+imwrite(intermediate, sprintf('%s.intermediate.png',prj_name),'png','alpha', matte);
+imwrite(edges, sprintf('%s.edges.png',prj_name),'png');
+imwrite(final, sprintf('%s.final.png',prj_name),'png','alpha', matte);
+

chromakey/to_param.m

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+## 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} =} to_param (@var{input1}, @var{input2})
+##
+## @seealso{}
+## @end deftypefn
+
+## Author: Jens <jens@orion>
+## Created: 2020-10-07
+
+function p = to_param(x, pmin, pmax, B, k, pcenter, scenter)
+
+	if (pmin == pmax)
+		pmax += 1E-9;
+	end
+
+	if (k == 0)
+		k = 1E-9;
+	end
+
+	if ((pcenter < pmin) || (pcenter > pmax))
+	    pcenter = pmax*scenter + pmin*(1-scenter);
+	end
+
+	x = min(1, max(0, x));
+	kc = 1/(B^k-1);
+	p = [];
+	for n=1:length(x);
+		s = x(n);
+		if (s < scenter)
+			s = (scenter-s)/scenter;
+			ks = -(pcenter-pmin);
+		else
+			s = (-scenter+s)/(1-scenter);
+			ks = (pmax-pcenter);
+		end
+		if (B == 1)
+			p = [p pcenter + ks*kc*s];
+		else
+			p = [p pcenter + ks*kc*(B.^(k*s)-1)];
+		end
+	end	
+endfunction
+