82 lines
2.0 KiB
Matlab
82 lines
2.0 KiB
Matlab
## Copyright (C) 2020 Jens
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##
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## This program is free software: you can redistribute it and/or modify it
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## under the terms of the GNU General Public License as published by
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## the Free Software Foundation, either version 3 of the License, or
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## (at your option) any later version.
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##
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## This program is distributed in the hope that it will be useful, but
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## WITHOUT ANY WARRANTY; without even the implied warranty of
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## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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## GNU General Public License for more details.
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##
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## You should have received a copy of the GNU General Public License
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## along with this program. If not, see
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## <https://www.gnu.org/licenses/>.
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## -*- texinfo -*-
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## @deftypefn {} {@var{retval} =} alpha_gen (@var{input1}, @var{input2})
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##
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## @seealso{}
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## @end deftypefn
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## Author: Jens <jens@orion>
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## Created: 2020-10-07
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function a = alpha_gen(N, slope)
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s = (0:N-1)/(N-1);
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a = to_param(s, 0, 1, 2, -slope, 0.5, 0.5);
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color_bg = [0.1 0.3 0.9];
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color_fg = [0.9 0.9 0.0];
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mean_fg = mean(color_fg)
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norm_fg = norm(color_fg)
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mean_bg = mean(color_bg)
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norm_bg = norm(color_bg)
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w = N;
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h = 8;
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im_a = repmat(a, h, 1);
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im_comp = to_im (color_fg, a, h) + to_im (color_bg, 1-a, h);
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im_fg = to_ref(color_fg, size(im_comp));
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im_bg = to_ref(color_bg, size(im_comp));
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im_ac = (im_comp - im_bg)./(im_fg - im_bg);
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close all;
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figure;
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imshow(im_a); title ("im_a")
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figure;
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imshow(im_ac); title ("im_ac")
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figure;
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imshow(im_comp); title ("im_comp")
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figure;
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im_filtered = im_comp - to_ref(color_bg, size(im_comp));
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imshow(im_filtered); title ("im_filtered")
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strip = im_filtered(1,:,:);
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strip_clamped = max(0, strip);
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strip_clamped_norm = strip_clamped;
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n = vecnorm(strip, 2, 3)/norm_fg;
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figure;
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plot (s, a, s, n); grid; legend("Ground truth", "Calculated")
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endfunction
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function im = to_im(color, a, h)
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w = length(a);
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im = reshape([color(1)*ones(h,1)*a color(2)*ones(h,1)*a color(3)*ones(h,1)*a], h, w, 3);
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endfunction
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function r = to_ref(ref, d)
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r = repmat(reshape(ref,1, 1, 3), d(1), d(2));
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endfunction
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