reduce.hh

// Copyright (C) 2009 EPITA Research and Development Laboratory (LRDE)
//
// This file is part of Olena.
//
// Olena is free software: you can redistribute it and/or modify it under
// the terms of the GNU General Public License as published by the Free
// Software Foundation, version 2 of the License.
//
// Olena is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
// General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with Olena.  If not, see <http://www.gnu.org/licenses/>.
//
// As a special exception, you may use this file as part of a free
// software project without restriction.  Specifically, if other files
// instantiate templates or use macros or inline functions from this
// file, or you compile this file and link it with other files to produce
// an executable, this file does not by itself cause the resulting
// executable to be covered by the GNU General Public License.  This
// exception does not however invalidate any other reasons why the
// executable file might be covered by the GNU General Public License.

#ifndef MLN_WORLD_BINARY_2D_REDUCE_HH
# define MLN_WORLD_BINARY_2D_REDUCE_HH




namespace mln
{

  namespace world
  {

    namespace binary_2d
    {


      image2d<bool>
      reduce(const image2d<bool>& input);


# ifndef MLN_INCLUDE_ONLY


      image2d<bool>
      reduce(const image2d<bool>& input)
      {
        trace::entering("world::binary_2d::reduce");

        mln_precondition(input.is_valid());

        const int
          min_row = input.domain().pmin().row(),
          min_col = input.domain().pmin().col(),
          max_row = input.domain().pmax().row(),
          max_col = input.domain().pmax().col();

        image2d<bool> output(input.nrows() / 2,
                             input.ncols() / 2);

        for (int row = min_row; row <= max_row; row += 2)
          for (int col = min_col; col <= max_col; col += 2)
          {
            unsigned count = 0;
            if (input.at_(row,     col)     == true) ++count;
            if (input.at_(row,     col + 1) == true) ++count;
            if (input.at_(row + 1, col)     == true) ++count;
            if (input.at_(row + 1, col + 1) == true) ++count;
            output.at_((row - min_row) / 2,
                       (col - min_col) / 2) = (count >= 2);
          }

        trace::exiting("world::binary_2d::reduce");
        return output;
      }


# endif ! // MLN_INCLUDE_ONLY


    } // end of namespace mln::world::binary_2d

  } // end of namespace mln::world

} // end of namespace mln


# endif // ! MLN_WORLD_BINARY_2D_REDUCE_HH