Median.hpp

#ifndef EYE_SHADERS_MEDIAN_HPP
#define EYE_SHADERS_MEDIAN_HPP
 
#include <shrimp/ColorTypes.hpp>
 
#include "shadersDllApi.h"
 
extern shaders_API constinit const char Median_GLSL[];
 
 
#define s2(a, b)                        temp = a; a = min(a, b); b = max(temp, b);
#define mn3(a, b, c)                    s2(a, b); s2(a, c);
#define mx3(a, b, c)                    s2(b, c); s2(a, c);
 
#define mnmx3(a, b, c)                  mx3(a, b, c); s2(a, b);                                   // 3 exchanges
#define mnmx4(a, b, c, d)               s2(a, b); s2(c, d); s2(a, c); s2(b, d);                   // 4 exchanges
#define mnmx5(a, b, c, d, e)    s2(a, b); s2(c, d); mn3(a, c, e); mx3(b, d, e);           // 6 exchanges
#define mnmx6(a, b, c, d, e, f) s2(a, d); s2(b, e); s2(c, f); mn3(a, b, c); mx3(d, e, f); // 7 exchanges
 
 
/*
3x3 Median
Morgan McGuire and Kyle Whitson
http://graphics.cs.williams.edu
https://casual-effects.com/research/McGuire2008Median/median.pix
 
 
Copyright (c) Morgan McGuire and Williams College, 2006
All rights reserved.
 
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are
met:
 
Redistributions of source code must retain the above copyright notice,
this list of conditions and the following disclaimer.
 
Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in the
documentation and/or other materials provided with the distribution.
 
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
template <class T>
inline  T median(std::array<T,9> v)
{
T       temp;
 
        // Starting with a subset of size 6, remove the min and max each time
        mnmx6(v[0], v[1], v[2], v[3], v[4], v[5]);
        mnmx5(v[1], v[2], v[3], v[4], v[6]);
        mnmx4(v[2], v[3], v[4], v[7]);
        mnmx3(v[3], v[4], v[8]);
 
        return v[4];
}
 
#undef s2
#undef mn3
#undef mx3
#undef mnmx3
#undef mnmx4
#undef mnmx5
#undef mnmx6
 
 
 
 
 
 
#define s2(a, b)                                temp = a; a = min(a, b); b = max(temp, b);
#define t2(a, b)                                s2(v[a], v[b]);
#define t24(a, b, c, d, e, f, g, h)             t2(a, b); t2(c, d); t2(e, f); t2(g, h);
#define t25(a, b, c, d, e, f, g, h, i, j)       t24(a, b, c, d, e, f, g, h); t2(i, j);
 
template <class T>
inline  T median(std::array<T,25> & v)
{
T       temp;
 
        t25(0, 1,               3, 4,           2, 4,           2, 3,           6, 7);
        t25(5, 7,               5, 6,           9, 7,           1, 7,           1, 4);
        t25(12, 13,             11, 13,         11, 12,         15, 16,         14, 16);
        t25(14, 15,             18, 19,         17, 19,         17, 18,         21, 22);
        t25(20, 22,             20, 21,         23, 24,         2, 5,           3, 6);
        t25(0, 6,               0, 3,           4, 7,           1, 7,           1, 4);
        t25(11, 14,             8, 14,          8, 11,          12, 15,         9, 15);
        t25(9, 12,              13, 16,         10, 16,         10, 13,         20, 23);
        t25(17, 23,             17, 20,         21, 24,         18, 24,         18, 21);
        t25(19, 22,             8, 17,          9, 18,          0, 18,          0, 9);
        t25(10, 19,             1, 19,          1, 10,          11, 20,         2, 20);
        t25(2, 11,              12, 21,         3, 21,          3, 12,          13, 22);
        t25(4, 22,              4, 13,          14, 23,         5, 23,          5, 14);
        t25(15, 24,             6, 24,          6, 15,          7, 16,          7, 19);
        t25(3, 11,              5, 17,          11, 17,         9, 17,          4, 10);
        t25(6, 12,              7, 14,          4, 6,           4, 7,           12, 14);
        t25(10, 14,             6, 7,           10, 12,         6, 10,          6, 17);
        t25(12, 17,             7, 17,          7, 10,          12, 18,         7, 12);
        t24(10, 18,             12, 20,         10, 20,         10, 12);
 
        return v[12];
}
 
#undef s2
#undef t2
#undef t25
#undef t24
 
 
#endif // EYE_SHADERS_MEDIAN_HPP