1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
|
/*=========================================================================
*
* Copyright NumFOCUS
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* https://www.apache.org/licenses/LICENSE-2.0.txt
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
*=========================================================================*/
// Software Guide : BeginLatex
//
// This example illustrates the use of the \code{SetPixel()} and
// \code{GetPixel()} methods. These two methods provide direct access to the
// pixel data contained in the image. Note that these two methods are
// relatively slow and should not be used in situations where
// high-performance access is required. Image iterators are the appropriate
// mechanism to efficiently access image pixel data. (See
// Chapter~\ref{sec:ImageIteratorsChapter} on page
// \pageref{sec:ImageIteratorsChapter} for information about image
// iterators.)
//
// Software Guide : EndLatex
#include "itkImage.h"
int
main(int, char *[])
{
// First the image type should be declared
using ImageType = itk::Image<unsigned short, 3>;
// Then the image object can be created
auto image = ImageType::New();
// The image region should be initialized
const ImageType::SizeType size = {
{ 200, 200, 200 }
}; // Size along {X,Y,Z}
const ImageType::IndexType start = {
{ 0, 0, 0 }
}; // First index on {X,Y,Z}
ImageType::RegionType region;
region.SetSize(size);
region.SetIndex(start);
// Pixel data is allocated
image->SetRegions(region);
image->Allocate(true); // initialize buffer to zero
// Software Guide : BeginLatex
//
// The individual position of a pixel inside the image is identified by a
// unique index. An index is an array of integers that defines the position
// of the pixel along each dimension of the image. The \code{IndexType}
// is automatically defined by the image and can be accessed using the
// scope operator \doxygen{Index}. The length of the array will match
// the dimensions of the associated image.
//
// The following code illustrates the declaration of an index variable and
// the assignment of values to each of its components. Please note that
// no \code{SmartPointer} is used to access the \code{Index}. This is
// because \code{Index} is a lightweight object that is not intended to be
// shared between objects. It is more efficient to produce multiple copies
// of these small objects than to share them using the SmartPointer
// mechanism.
//
// The following lines declare an instance of the index type and initialize
// its content in order to associate it with a pixel position in the image.
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
const ImageType::IndexType pixelIndex = {
{ 27, 29, 37 }
}; // Position of {X,Y,Z}
// Software Guide : EndCodeSnippet
// Software Guide : BeginLatex
//
// Having defined a pixel position with an index, it is then possible to
// access the content of the pixel in the image. The \code{GetPixel()}
// method allows us to get the value of the pixels.
//
// \index{itk::Image!GetPixel()}
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
ImageType::PixelType pixelValue = image->GetPixel(pixelIndex);
// Software Guide : EndCodeSnippet
// Software Guide : BeginLatex
//
// The \code{SetPixel()} method allows us to set the value of the pixel.
//
// \index{itk::Image!SetPixel()}
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
image->SetPixel(pixelIndex, pixelValue + 1);
// Software Guide : EndCodeSnippet
// Software Guide : BeginLatex
//
// Please note that \code{GetPixel()} returns the pixel value using copy
// and not reference semantics. Hence, the method cannot be used to
// modify image data values.
//
// Remember that both \code{SetPixel()} and \code{GetPixel()} are
// inefficient and should only be used for debugging or for supporting
// interactions like querying pixel values by clicking with the mouse.
//
// Software Guide : EndLatex
return EXIT_SUCCESS;
}
|
