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median_cut.cpp

  1 /* Copyright (c) 2010 the authors listed at the following URL, and/or
  2 the authors of referenced articles or incorporated external code:
  3 http://en.literateprograms.org/Median_cut_algorithm_(C_Plus_Plus)?action=history&offset=20080309133934
  4 
  5 Permission is hereby granted, free of charge, to any person obtaining
  6 a copy of this software and associated documentation files (the
  7 "Software"), to deal in the Software without restriction, including
  8 without limitation the rights to use, copy, modify, merge, publish,
  9 distribute, sublicense, and/or sell copies of the Software, and to
 10 permit persons to whom the Software is furnished to do so, subject to
 11 the following conditions:
 12 
 13 The above copyright notice and this permission notice shall be
 14 included in all copies or substantial portions of the Software.
 15 
 16 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 17 EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 18 MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
 19 IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
 20 CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
 21 TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
 22 SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 23 
 24 Retrieved from: http://en.literateprograms.org/Median_cut_algorithm_(C_Plus_Plus)?oldid=12754
 25 */
 26 
 27 #include <limits>

 28 
 29 #include <queue>

 30 #include <algorithm>

 31 
 32 #include "median_cut.h"

 33 
 34 Block::Block(Point* points, int pointsLength)
 35 {
 36     this->points = points;
 37     this->pointsLength = pointsLength;
 38     for(int i=0; i < NUM_DIMENSIONS; i++)
 39     {
 40         minCorner.x[i] = std::numeric_limits<unsigned char>::min();
 41         maxCorner.x[i] = std::numeric_limits<unsigned char>::max();
 42     }
 43 }
 44 
 45 Point * Block::getPoints()
 46 {
 47     return points;
 48 }
 49 
 50 int Block::numPoints() const
 51 {
 52     return pointsLength;
 53 }
 54 
 55 int Block::longestSideIndex() const
 56 {
 57     int m = maxCorner.x[0] - minCorner.x[0];
 58     int maxIndex = 0;
 59     for(int i=1; i < NUM_DIMENSIONS; i++)
 60     {
 61         int diff = maxCorner.x[i] - minCorner.x[i];
 62         if (diff > m)
 63         {
 64             m = diff;
 65             maxIndex = i;
 66         }
 67     }
 68     return maxIndex;
 69 }
 70 
 71 int Block::longestSideLength() const
 72 {
 73     int i = longestSideIndex();
 74     return maxCorner.x[i] - minCorner.x[i];
 75 }
 76 
 77 bool Block::operator<(const Block& rhs) const
 78 {
 79     return this->longestSideLength() < rhs.longestSideLength();
 80 }
 81 
 82 void Block::shrink()
 83 {
 84     int i,j;
 85     for(j=0; j<NUM_DIMENSIONS; j++)
 86     {
 87         minCorner.x[j] = maxCorner.x[j] = points[0].x[j];
 88     }
 89     for(i=1; i < pointsLength; i++)
 90     {
 91         for(j=0; j<NUM_DIMENSIONS; j++)
 92         {
 93             minCorner.x[j] = min(minCorner.x[j], points[i].x[j]);
 94             maxCorner.x[j] = max(maxCorner.x[j], points[i].x[j]);
 95         }
 96     }
 97 }
 98 
 99 std::list<Point> medianCut(Point* image, int numPoints, unsigned int desiredSize)
100 {
101     std::priority_queue<Block> blockQueue;
102 
103     Block initialBlock(image, numPoints);
104     initialBlock.shrink();
105 
106     blockQueue.push(initialBlock);
107     while (blockQueue.size() < desiredSize && blockQueue.top().numPoints() > 1)
108     {
109         Block longestBlock = blockQueue.top();
110 
111         blockQueue.pop();
112         Point * begin  = longestBlock.getPoints();
113 	Point * median = longestBlock.getPoints() + (longestBlock.numPoints()+1)/2;
114 	Point * end    = longestBlock.getPoints() + longestBlock.numPoints();
115 	switch(longestBlock.longestSideIndex())
116 	{
117 	case 0: std::nth_element(begin, median, end, CoordinatePointComparator<0>()); break;
118 	case 1: std::nth_element(begin, median, end, CoordinatePointComparator<1>()); break;
119 	case 2: std::nth_element(begin, median, end, CoordinatePointComparator<2>()); break;
120 	}
121 
122 	Block block1(begin, median-begin), block2(median, end-median);
123 	block1.shrink();
124 	block2.shrink();
125 
126         blockQueue.push(block1);
127         blockQueue.push(block2);
128     }
129 
130     std::list<Point> result;
131     while(!blockQueue.empty())
132     {
133         Block block = blockQueue.top();
134         blockQueue.pop();
135         Point * points = block.getPoints();
136 
137         int sum[NUM_DIMENSIONS] = {0};
138         for(int i=0; i < block.numPoints(); i++)
139         {
140             for(int j=0; j < NUM_DIMENSIONS; j++)
141             {
142                 sum[j] += points[i].x[j];
143             }
144         }
145 
146         Point averagePoint;
147         for(int j=0; j < NUM_DIMENSIONS; j++)
148         {
149             averagePoint.x[j] = sum[j] / block.numPoints();
150         }
151 
152         result.push_back(averagePoint);
153     }
154 
155     return result;
156 }
157 
158


median_cut.h

 1 /* Copyright (c) 2010 the authors listed at the following URL, and/or
 2 the authors of referenced articles or incorporated external code:
 3 http://en.literateprograms.org/Median_cut_algorithm_(C_Plus_Plus)?action=history&offset=20080309133934
 4 
 5 Permission is hereby granted, free of charge, to any person obtaining
 6 a copy of this software and associated documentation files (the
 7 "Software"), to deal in the Software without restriction, including
 8 without limitation the rights to use, copy, modify, merge, publish,
 9 distribute, sublicense, and/or sell copies of the Software, and to
10 permit persons to whom the Software is furnished to do so, subject to
11 the following conditions:
12 
13 The above copyright notice and this permission notice shall be
14 included in all copies or substantial portions of the Software.
15 
16 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
17 EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
18 MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
19 IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
20 CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
21 TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
22 SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
23 
24 Retrieved from: http://en.literateprograms.org/Median_cut_algorithm_(C_Plus_Plus)?oldid=12754
25 */
26 
27 #ifndef MEDIAN_CUT_H_

28 #define MEDIAN_CUT_H_

29 #include <list>

30 
31 const int NUM_DIMENSIONS = 3;
32 
33 struct Point
34 {
35     unsigned char x[NUM_DIMENSIONS];
36 };
37 
38 class Block
39 {
40     Point minCorner, maxCorner;
41     Point* points;
42     int pointsLength;
43 public:
44     Block(Point* points, int pointsLength);
45     Point * getPoints();
46     int numPoints() const;
47     int longestSideIndex() const;
48     int longestSideLength() const;
49     bool operator<(const Block& rhs) const;
50     void shrink();
51 private:
52     template <typename T>
53     static T min(const T a, const T b)
54     {
55         if (a < b)
56             return a;
57         else
58             return b;
59     }
60 
61     template <typename T>
62     static T max(const T a, const T b)
63     {
64         if (a > b)
65             return a;
66         else
67             return b;
68     }
69 
70 };
71 
72 template <int index>
73 class CoordinatePointComparator
74 {
75 public:
76     bool operator()(Point left, Point right)
77     {
78         return left.x[index] < right.x[index];
79     }
80 };
81 
82 std::list<Point> medianCut(Point* image, int numPoints, unsigned int desiredSize);
83 #endif /* #ifndef MEDIAN_CUT_H_ */

84


median_cut_sample.cpp

 1 /* Copyright (c) 2010 the authors listed at the following URL, and/or
 2 the authors of referenced articles or incorporated external code:
 3 http://en.literateprograms.org/Median_cut_algorithm_(C_Plus_Plus)?action=history&offset=20080309133934
 4 
 5 Permission is hereby granted, free of charge, to any person obtaining
 6 a copy of this software and associated documentation files (the
 7 "Software"), to deal in the Software without restriction, including
 8 without limitation the rights to use, copy, modify, merge, publish,
 9 distribute, sublicense, and/or sell copies of the Software, and to
10 permit persons to whom the Software is furnished to do so, subject to
11 the following conditions:
12 
13 The above copyright notice and this permission notice shall be
14 included in all copies or substantial portions of the Software.
15 
16 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
17 EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
18 MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
19 IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
20 CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
21 TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
22 SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
23 
24 Retrieved from: http://en.literateprograms.org/Median_cut_algorithm_(C_Plus_Plus)?oldid=12754
25 */
26 
27 #include <iostream>

28 #include "median_cut.h"

29 
30 int main(int argc, char* argv[]) {
31     FILE * raw_in;
32     int numPoints = atoi(argv[2]) * atoi(argv[3]);
33     Point* points = (Point*)malloc(sizeof(Point) * numPoints);
34 
35     raw_in = fopen(argv[1], "rb");
36     for(int i = 0; i < numPoints; i++)
37     {
38         fread(&points[i], 3, 1, raw_in);
39     }
40     fclose(raw_in);
41 
42     std::list<Point> palette =
43         medianCut(points, numPoints, atoi(argv[4]));
44 
45     std::list<Point>::iterator iter;
46     for (iter = palette.begin() ; iter != palette.end(); iter++)
47     {
48         std::cout << (int)iter->x[0] << " "
49                   << (int)iter->x[1] << " "
50                   << (int)iter->x[2] << std::endl;
51     }
52 
53     return 0;
54 }
55


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