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niblack_functor_fast.hh
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26 
27 #ifndef SCRIBO_BINARIZATION_INTERNAL_NIBLACK_FUNCTOR_FAST_HH
28 # define SCRIBO_BINARIZATION_INTERNAL_NIBLACK_FUNCTOR_FAST_HH
29 
33 
34 # include <mln/core/image/image2d.hh>
35 # include <mln/core/alias/neighb2d.hh>
36 # include <mln/extension/fill.hh>
37 
38 # include <scribo/binarization/internal/niblack_formula.hh>
39 
40 # ifdef SCRIBO_LOCAL_THRESHOLD_DEBUG
41 # include <scribo/binarization/internal/local_threshold_debug.hh>
42 # endif // ! SCRIBO_LOCAL_THRESHOLD_DEBUG
43 
44 
45 namespace scribo
46 {
47 
48  namespace binarization
49  {
50 
51  namespace internal
52  {
53 
54  using namespace mln;
55 
56 
57  template <typename I>
59  {
60  niblack_functor_fast(const Image<I>& input, double K);
61 
62  // Moves in input and output images are made using "step"
63  // pixels. It corresponds to the scale ratio between the input
64  // image and the integral image used to give the statistics
65  // values.
66  enum { step = 3 };
67 
68  void init();
69 
70  // Run every 4 pixels.
71  void exec(double mean, double stddev);
72 
73  void end_of_row(int);
74 
75  void finalize();
76 
77 
78  const I input;
79  mln_ch_value(I,bool) output;
80 
81  const mln_value(I)* pi;
82  bool* po;
83 
84  double K_;
85 
87 
88  unsigned next_line3;
89  unsigned offset1;
90  unsigned offset2;
91  };
92 
93 #ifndef MLN_INCLUDE_ONLY
94 
95  template <typename I>
97  double K)
98  : input(exact(input_)),
99  pi(&input(input.domain().pmin())),
100  K_(K)
101  {
102  mln_precondition(exact(input).is_valid());
103  }
104 
105  template <typename I>
106  void
107  niblack_functor_fast<I>::init()
108  {
109  // This initialization MUST be done here since input image
110  // borders may have changed!
111 
112  // Since we iterate from a smaller image in the largest ones
113  // and image at scale 1 does not always have a size which can
114  // be divided by 3, some sites in the border may not be
115  // processed and we must skip them.
116  int more_offset = - (3 - input.ncols() % 3);
117  if (more_offset == - 3)
118  more_offset = 0; // No offset needed.
119 
120  next_line3 = input.delta_offset(dpoint2d(+2,0))
121  + 2 * input.border() + more_offset;
122 
123  offset1 = input.delta_offset(dpoint2d(+1,0));
124  offset2 = input.delta_offset(dpoint2d(+2,0));
125 
126  initialize(output, input);
127  po = &output(output.domain().pmin());
128  }
129 
130  template <typename I>
131  void
132  niblack_functor_fast<I>::exec(double mean, double stddev)
133  {
134  double th = formula_(mean, stddev, K_);
135 
136  for (int i = 0; i < step; ++i, ++po, ++pi)
137  {
138  *po = (*pi <= th);
139  *(po + offset1) = (*(pi + offset1) <= th);
140  *(po + offset2) = (*(pi + offset2) <= th);
141  }
142 
143 # ifdef SCRIBO_LOCAL_THRESHOLD_DEBUG
144  // Store local mean
145  unsigned index = pi - input.buffer();
146 
147  debug_mean.element(index) = mean * mean_debug_factor;
148  debug_stddev.element(index) = stddev * stddev_debug_factor;
149  debug_threshold.element(index) = th;
150 # endif // ! SCRIBO_LOCAL_THRESHOLD_DEBUG
151 
152  }
153 
154  template <typename I>
155  void
156  niblack_functor_fast<I>::end_of_row(int)
157  {
158  po += next_line3;
159  pi += next_line3;
160  }
161 
162  template <typename I>
163  void
164  niblack_functor_fast<I>::finalize()
165  {
166  }
167 
168 #endif // ! MLN_INCLUDE_ONLY
169 
170  } // end of namespace scribo::binarization::internal
171 
172  } // end of namespace scribo::binarization
173 
174 } // end of namespace scribo
175 
176 #endif // SCRIBO_BINARIZATION_INTERNAL_NIBLACK_FUNCTOR_FAST_HH