boost/gil/extension/numeric/sampler.hpp

   1 //
   2 // Copyright 2005-2007 Adobe Systems Incorporated
   3 //
   4 // Distributed under the Boost Software License, Version 1.0
   5 // See accompanying file LICENSE_1_0.txt or copy at
   6 // http://www.boost.org/LICENSE_1_0.txt
   7 //
   8 #ifndef BOOST_GIL_EXTENSION_NUMERIC_SAMPLER_HPP
   9 #define BOOST_GIL_EXTENSION_NUMERIC_SAMPLER_HPP
  10
  11 #include <boost/gil/extension/numeric/pixel_numeric_operations.hpp>
  12 #include <boost/gil/extension/dynamic_image/dynamic_image_all.hpp>
  13
  14 namespace boost { namespace gil {
  15
  16 // Nearest-neighbor and bilinear image samplers.
  17 // NOTE: The code is for example use only. It is not optimized for performance
  18
  19 ///////////////////////////////////////////////////////////////////////////
  20 ////
  21 ////     resample_pixels: set each pixel in the destination view as the result of a sampling function over the transformed coordinates of the source view
  22 ////
  23 ///////////////////////////////////////////////////////////////////////////
  24 /*
  25 template <typename Sampler>
  26 concept SamplerConcept {
  27     template <typename DstP,      // Models PixelConcept
  28               typename SrcView,    // Models RandomAccessNDImageViewConcept
  29               typename S_COORDS>  // Models PointNDConcept, where S_COORDS::num_dimensions == SrcView::num_dimensions
  30     bool sample(const Sampler& s, const SrcView& src, const S_COORDS& p, DstP result);
  31 };
  32 */
  33
  34 /// \brief A sampler that sets the destination pixel to the closest one in the source. If outside the bounds, it doesn't change the destination
  35 /// \ingroup ImageAlgorithms
  36 struct nearest_neighbor_sampler {};
  37
  38 template <typename DstP, typename SrcView, typename F>
  39 bool sample(nearest_neighbor_sampler, SrcView const& src, point<F> const& p, DstP& result)
  40 {
  41     typename SrcView::point_t center(iround(p));
  42     if (center.x >= 0 && center.y >= 0 && center.x < src.width() && center.y < src.height())
  43     {
  44         result=src(center.x,center.y);
  45         return true;
  46     }
  47     return false;
  48 }
  49
  50 struct cast_channel_fn {
  51     template <typename SrcChannel, typename DstChannel>
  52     void operator()(const SrcChannel& src, DstChannel& dst) {
  53         using dst_value_t = typename channel_traits<DstChannel>::value_type;
  54         dst = dst_value_t(src);
  55     }
  56 };
  57
  58 template <typename SrcPixel, typename DstPixel>
  59 void cast_pixel(const SrcPixel& src, DstPixel& dst) {
  60     static_for_each(src,dst,cast_channel_fn());
  61 }
  62
  63 namespace detail {
  64
  65 template <typename Weight>
  66 struct add_dst_mul_src_channel {
  67     Weight _w;
  68     add_dst_mul_src_channel(Weight w) : _w(w) {}
  69
  70     template <typename SrcChannel, typename DstChannel>
  71     void operator()(const SrcChannel& src, DstChannel& dst) const {
  72         dst += DstChannel(src*_w);
  73     }
  74 };
  75
  76 // dst += DST_TYPE(src * w)
  77 template <typename SrcP,typename Weight,typename DstP>
  78 struct add_dst_mul_src {
  79     void operator()(const SrcP& src, Weight weight, DstP& dst) const {
  80         static_for_each(src,dst, add_dst_mul_src_channel<Weight>(weight));
  81 //        pixel_assigns_t<DstP,DstP&>()(
  82 //            pixel_plus_t<DstP,DstP,DstP>()(
  83 //                pixel_multiplies_scalar_t<SrcP,Weight,DstP>()(src,weight),
  84 //                dst),
  85 //            dst);
  86     }
  87 };
  88 } // namespace detail
  89
  90 /// \brief A sampler that sets the destination pixel as the bilinear interpolation of the four closest pixels from the source.
  91 /// If outside the bounds, it doesn't change the destination
  92 /// \ingroup ImageAlgorithms
  93 struct bilinear_sampler {};
  94
  95 template <typename DstP, typename SrcView, typename F>
  96 bool sample(bilinear_sampler, SrcView const& src, point<F> const& p, DstP& result)
  97 {
  98     using SrcP = typename SrcView::value_type;
  99     point_t p0(ifloor(p.x), ifloor(p.y)); // the closest integer coordinate top left from p
 100     point<F> frac(p.x-p0.x, p.y-p0.y);
 101
 102     if (p0.x < -1 || p0.y < -1 || p0.x>=src.width() || p0.y>=src.height())
 103     {
 104         return false;
 105     }
 106
 107         pixel<F,devicen_layout_t<num_channels<SrcView>::value> > mp(0); // suboptimal
 108         typename SrcView::xy_locator loc=src.xy_at(p0.x,p0.y);
 109
 110         if (p0.x == -1)
 111     {
 112                 if (p0.y == -1)
 113         {
 114                     // the top-left corner pixel
 115                         ++loc.y();
 116                         detail::add_dst_mul_src<SrcP,F,pixel<F,devicen_layout_t<num_channels<SrcView>::value> > >()(loc.x()[1],  1        ,mp);
 117                 }
 118         else if (p0.y+1<src.height())
 119         {
 120             // on the first column, but not the top-left nor bottom-left corner pixel
 121                         detail::add_dst_mul_src<SrcP,F,pixel<F,devicen_layout_t<num_channels<SrcView>::value> > >()(loc.x()[1], (1-frac.y),mp);
 122                         ++loc.y();
 123                         detail::add_dst_mul_src<SrcP,F,pixel<F,devicen_layout_t<num_channels<SrcView>::value> > >()(loc.x()[1],    frac.y ,mp);
 124                 }
 125         else
 126         {
 127                         // the bottom-left corner pixel
 128                         detail::add_dst_mul_src<SrcP,F,pixel<F,devicen_layout_t<num_channels<SrcView>::value> > >()(loc.x()[1],  1        ,mp);
 129                 }
 130         }
 131     else if (p0.x+1<src.width())
 132     {
 133                 if (p0.y == -1)
 134         {
 135                     // on the first row, but not the top-left nor top-right corner pixel
 136                         ++loc.y();
 137                         detail::add_dst_mul_src<SrcP,F,pixel<F,devicen_layout_t<num_channels<SrcView>::value> > >()(*loc,      (1-frac.x)           ,mp);
 138                         detail::add_dst_mul_src<SrcP,F,pixel<F,devicen_layout_t<num_channels<SrcView>::value> > >()(loc.x()[1],   frac.x            ,mp);
 139                 }
 140         else if (p0.y+1<src.height())
 141         {
 142                         // most common case - inside the image, not on the frist nor last row/column
 143                         detail::add_dst_mul_src<SrcP,F,pixel<F,devicen_layout_t<num_channels<SrcView>::value> > >()(*loc,      (1-frac.x)*(1-frac.y),mp);
 144                         detail::add_dst_mul_src<SrcP,F,pixel<F,devicen_layout_t<num_channels<SrcView>::value> > >()(loc.x()[1],   frac.x *(1-frac.y),mp);
 145                         ++loc.y();
 146                         detail::add_dst_mul_src<SrcP,F,pixel<F,devicen_layout_t<num_channels<SrcView>::value> > >()(*loc,      (1-frac.x)*   frac.y ,mp);
 147                         detail::add_dst_mul_src<SrcP,F,pixel<F,devicen_layout_t<num_channels<SrcView>::value> > >()(loc.x()[1],   frac.x *   frac.y ,mp);
 148                 }
 149         else
 150         {
 151                         // on the last row, but not the bottom-left nor bottom-right corner pixel
 152                         detail::add_dst_mul_src<SrcP,F,pixel<F,devicen_layout_t<num_channels<SrcView>::value> > >()(*loc,      (1-frac.x)           ,mp);
 153                         detail::add_dst_mul_src<SrcP,F,pixel<F,devicen_layout_t<num_channels<SrcView>::value> > >()(loc.x()[1],   frac.x            ,mp);
 154                 }
 155         }
 156     else
 157     {
 158         if (p0.y == -1)
 159         {
 160             // the top-right corner pixel
 161             ++loc.y();
 162             detail::add_dst_mul_src<SrcP,F,pixel<F,devicen_layout_t<num_channels<SrcView>::value> > >()(*loc,  1        ,mp);
 163         }
 164         else if (p0.y+1<src.height())
 165         {
 166                         // on the last column, but not the top-right nor bottom-right corner pixel
 167                         detail::add_dst_mul_src<SrcP,F,pixel<F,devicen_layout_t<num_channels<SrcView>::value> > >()(*loc, (1-frac.y),mp);
 168                         ++loc.y();
 169                         detail::add_dst_mul_src<SrcP,F,pixel<F,devicen_layout_t<num_channels<SrcView>::value> > >()(*loc,    frac.y ,mp);
 170                 }
 171         else
 172         {
 173                         // the bottom-right corner pixel
 174                         detail::add_dst_mul_src<SrcP,F,pixel<F,devicen_layout_t<num_channels<SrcView>::value> > >()(*loc,  1        ,mp);
 175                 }
 176         }
 177
 178         // Convert from floating point average value to the source type
 179         SrcP src_result;
 180         cast_pixel(mp,src_result);
 181
 182         color_convert(src_result, result);
 183         return true;
 184 }
 185
 186 }}  // namespace boost::gil
 187
 188 #endif