void down_sample( const SRC& src_view
, const DST& dst_view )
{
assert( src_view.dimensions() == dst_view.dimensions() );
// @todo Take care of signed images. Bransform them into unsigned images
// by adding half the value range to the channels.
typedef SRC::value_type src_pixel_t;
typedef DST::value_type dst_pixel_t;
typedef channel_type<dst_pixel_t>::type dst_channel_t;
boost::fusion::vector<src_pixel_t,src_pixel_t> minmax = minmax_channel_values<src_pixel_t>( src_view );
const src_pixel_t& min = at_c<0>( minmax );
const src_pixel_t& max = at_c<1>( minmax );
// calculate the diff
src_pixel_t diff;
static_for_each( diff, min, max, calc_diff() );
// sample down
dst_channel_t dst_max = channel_traits< dst_channel_t >::max_value();
for ( int y=0; y < src_view.height(); ++y )
{
SRC::x_iterator src_it = src_view.row_begin( y );
DST::x_iterator dst_it = dst_view.row_begin( y );
for ( int x = 0; x < src_view.width(); ++x )
{
typename src_pixel_t::const_reference src = src_it[x];
typename dst_pixel_t::reference dst = dst_it[x];
for ( int i = 0; i < num_channels<src_pixel_t>::type::value; ++i )
{
if ( dynamic_at_c( diff, i ) == 0 )
{
dynamic_at_c( dst, i ) = 0;
}
else
{
dynamic_at_c( dst, i ) = static_cast<dst_channel_t>( dst_max * ( static_cast<float>( dynamic_at_c( src, i )
- dynamic_at_c( min, i ))
/ static_cast<float>( dynamic_at_c( diff, i ))));
} // else
} //for
} //for
} // for
}
