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reduce.hh
1 // Copyright (C) 2009 EPITA Research and Development Laboratory (LRDE)
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25 
26 #ifndef MLN_WORLD_BINARY_2D_REDUCE_HH
27 # define MLN_WORLD_BINARY_2D_REDUCE_HH
28 
29 
33 
34 
35 namespace mln
36 {
37 
38  namespace world
39  {
40 
41  namespace binary_2d
42  {
43 
44 
45  image2d<bool>
46  reduce(const image2d<bool>& input);
47 
48 
49 # ifndef MLN_INCLUDE_ONLY
50 
51 
52  image2d<bool>
53  reduce(const image2d<bool>& input)
54  {
55  trace::entering("world::binary_2d::reduce");
56 
57  mln_precondition(input.is_valid());
58 
59  const int
60  min_row = input.domain().pmin().row(),
61  min_col = input.domain().pmin().col(),
62  max_row = input.domain().pmax().row(),
63  max_col = input.domain().pmax().col();
64 
65  image2d<bool> output(input.nrows() / 2,
66  input.ncols() / 2);
67 
68  for (int row = min_row; row <= max_row; row += 2)
69  for (int col = min_col; col <= max_col; col += 2)
70  {
71  unsigned count = 0;
72  if (input.at_(row, col) == true) ++count;
73  if (input.at_(row, col + 1) == true) ++count;
74  if (input.at_(row + 1, col) == true) ++count;
75  if (input.at_(row + 1, col + 1) == true) ++count;
76  output.at_((row - min_row) / 2,
77  (col - min_col) / 2) = (count >= 2);
78  }
79 
80  trace::exiting("world::binary_2d::reduce");
81  return output;
82  }
83 
84 
85 # endif ! // MLN_INCLUDE_ONLY
86 
87 
88  } // end of namespace mln::world::binary_2d
89 
90  } // end of namespace mln::world
91 
92 } // end of namespace mln
93 
94 
95 # endif // ! MLN_WORLD_BINARY_2D_REDUCE_HH