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histo/equalize.hh
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26 
27 #ifndef MLN_HISTO_EQUALIZE_HH
28 # define MLN_HISTO_EQUALIZE_HH
29 
30 # include <cmath>
31 # include <mln/core/concept/image.hh>
32 # include <mln/histo/all.hh>
33 
37 
38 namespace mln
39 {
40 
41  namespace histo
42  {
43 
51  template <typename I>
52  mln_concrete(I) equalize(const Image<I>& input);
53 
54 
55 # ifndef MLN_INCLUDE_ONLY
56 
57  template <typename I>
58  mln_concrete(I)
59  equalize(const Image<I>& input_)
60  {
61  mln_trace("mln::histo::equalize");
62 
63  const I& input = exact(input_);
64  mln_precondition(input.is_valid());
65 
66  typedef mln_value(I) V;
67  array<V> histogram = compute(input);
68  array<V> histo_correction;
69 
70  unsigned nsites = input.nsites();
71  V max_color = mln_max(V);
72 
73  unsigned h_min = nsites;
74  mln_viter(mln::value::set<V>) v(histogram.vset());
75 
76  // Looking for minimum occurence in histogram
77  for_all(v)
78  if (histogram(v) > 0 && h_min > histogram(v))
79  h_min = histogram(v);
80 
81  // Computing new histogram.
82  unsigned cdf_v = 0;
83  for_all(v)
84  if (histogram(v) != 0)
85  {
86  cdf_v += histogram(v);
87  histo_correction(v)
88  = round((cdf_v - h_min) / (float)(nsites - h_min) * max_color);
89  }
90 
91  mln_concrete(I) output;
92  initialize(output, input);
93  mln_piter(I) p(input.domain());
94  for_all(p)
95  output(p) = histo_correction[input(p)];
96 
97  return output;
98  }
99 
100 # endif // ! MLN_INCLUDE_ONLY
101 
102  } // end of namespace mln::histo
103 
104 } // end of namespace mln
105 
106 
107 
108 #endif // ! MLN_HISTO_EQUALIZE_HH