vigra - vigra/meshgrid.hxx Source File

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meshgrid.hxx |

1 /************************************************************************/
2 /* */
3 /* Copyright 2009 by Ullrich Koethe */
4 /* */
5 /* This file is part of the VIGRA computer vision library. */
6 /* The VIGRA Website is */
7 /* http://hci.iwr.uni-heidelberg.de/vigra/ */
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9 /* ullrich.koethe@iwr.uni-heidelberg.de or */
10 /* vigra@informatik.uni-hamburg.de */
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13 /* obtaining a copy of this software and associated documentation */
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21 /* The above copyright notice and this permission notice shall be */
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33 /* */
34 /************************************************************************/
35
36 #ifndef VIGRA_MESHGRID_HXX
37 #define VIGRA_MESHGRID_HXX
38
39 #include "tinyvector.hxx"
40 #include "diff2d.hxx"
41
42 namespace vigra{
43 /** \addtogroup RangesAndPoints */
44 //@{
45
46 /********************************************************/
47 /* */
48 /* MeshGridAccessor */
49 /* */
50 /********************************************************/
51 /** Accessor for turning iteration over Diff2D into a mesh grid.
52
53 The mesh grid concept is adapted from MATLAB. It is a two banded image
54 (i.e. with 2D vector pixel type) whose first band contains the x-coordinates
55 of the current pixel, and whose second band contains the y-coordinates.
56 See \ref meshGrid() for more detailed documentation.
57 */
58 struct MeshGridAccessor
59 {
60 /** the value_type of a mesh grid is a 2D vector
61 */
62 typedef TinyVector<Diff2D::MoveX, 2> value_type;
63
64 /** read the current data item
65 */
66 template <class ITERATOR>
67 value_type operator()(ITERATOR const & i) const
68 {
69 return value_type(i->x, i->y);
70 }
71
72 /** read the data item at an offset (can be 1D or 2D or higher order difference).
73 */
74 template <class ITERATOR, class DIFFERENCE>
75 value_type operator()(ITERATOR const & i, DIFFERENCE const & diff) const
76 {
77 return value_type(i->x+diff.x, i->y+diff.y);
78 }
79 };
80
81 /** Create a mesh grid for the specified rectangle.
82
83 The mesh grid concept is adapted from MATLAB. It is a two banded image
84 (i.e. with 2D vector pixel type) whose first band contains the x-coordinates
85 of the current pixel, and whose second band contains the y-coordinates.
86 If \a upperLeft is not the point (0,0), the mesh grid is translated relative to
87 the pixel indices.
88
89 <b> Declarations:</b>
90
91 \code
92 triple<Diff2D, Diff2D, MeshGridAccessor>
93 meshGrid(Diff2D upperLeft, Diff2D lowerRight);
94
95 triple<Diff2D, Diff2D, MeshGridAccessor>
96 meshGrid(Rect2D const & r);
97
98 \endcode
99
100 <b>Usage:</b>
101
102 \code
103 #include <vigra/meshgrid.hxx>
104 // create an image whose values are equal to each pixel's distance from the image center
105 int width = 5, height = 7;
106 int xc = width/2, yc = height/2; // the image center
107
108 FImage dist(width, height);
109 Point2D upperLeft(-xc, -yc);
110
111 using namespace vigra::functor;
112 transformImage(meshGrid(upperLeft, upperLeft+dist.size()),
113 destImage(dist),
114 norm(Arg1()));
115 \endcode
116 */
117 inline
118 triple<Diff2D, Diff2D, MeshGridAccessor>
119 meshGrid(Diff2D upperLeft, Diff2D lowerRight)
120 {
121 return triple<Diff2D, Diff2D, MeshGridAccessor>(upperLeft, lowerRight, MeshGridAccessor());
122 }
123
124 inline
125 triple<Diff2D, Diff2D, MeshGridAccessor>
126 meshGrid(Rect2D const & r)
127 {
128 return triple<Diff2D, Diff2D, MeshGridAccessor>(r.upperLeft(), r.lowerRight(), MeshGridAccessor());
129 }
130
131 }//namespace vigra
132 //@}
133 #endif //VIGRA_MESHGRID_HXX

© Ullrich Köthe (ullrich.koethe@iwr.uni-heidelberg.de) Heidelberg Collaboratory for Image Processing, University of Heidelberg, Germany | html generated using doxygen and Python vigra 1.10.0 (Mon Nov 18 2013)