Question

我找到了这个itk矢量图像的例子，我不明白Vector Pixel类型的每个组件的含义例如代码行pixelValue [0] = 1.345;分量X是指灰度值或距图像矩阵内的下一个像素的距离



    /*=========================================================================
 *
 *  Copyright Insight Software Consortium
 *
 *  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
 *
 *         http://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
//
// Many image processing tasks require images of non-scalar pixel type. A
// typical example is an image of vectors. This is the image type required to
// represent the gradient of a scalar image. The following code illustrates
// how to instantiate and use an image whose pixels are of vector type.
//
// For convenience we use the \doxygen{Vector} class to define the pixel
// type.  The Vector class is intended to represent a geometrical vector in
// space. It is not intended to be used as an array container like the
// \href{http://www.sgi.com/tech/stl/Vector.html}{\code{std::vector}} in
// \href{http://www.sgi.com/tech/stl/}{STL}.  If you are interested in
// containers, the \doxygen{VectorContainer} class may provide the
// functionality you want.
//
// \index{itk::Vector}
// \index{itk::Vector!header}
//
//
// The first step is to include the header file of the Vector class.
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
#include "itkVector.h"
// Software Guide : EndCodeSnippet
#include "itkImage.h"
int main(int, char *[])
{
  // Software Guide : BeginLatex
  //
  // The Vector class is templated over the type used to represent
  // the coordinate in space and over the dimension of the space.  In this example,
  // we want the vector dimension to match the image dimension, but this is by
  // no means a requirement. We could have defined a four-dimensional image
  // with three-dimensional vectors as pixels.
  //
  // \index{itk::Vector!Instantiation}
  // \index{itk::Vector!itk::Image}
  // \index{itk::Image!Vector pixel}
  //
  // Software Guide : EndLatex
  // Software Guide : BeginCodeSnippet
  typedef itk::Vector< float, 3 >       PixelType;
  typedef itk::Image< PixelType, 3 >    ImageType;
  // Software Guide : EndCodeSnippet
  // Then the image object can be created
  ImageType::Pointer image = ImageType::New();
  // The image region should be initialized
  const ImageType::IndexType start = {{0,0,0}}; //First index at {X,Y,Z}
  const ImageType::SizeType  size = {{200,200,200}}; //Size of {X,Y,Z}
  ImageType::RegionType region;
  region.SetSize( size );
  region.SetIndex( start );
  // Pixel data is allocated
  image->SetRegions( region );
  image->Allocate();
  // The image buffer is initialized to a particular value
  ImageType::PixelType  initialValue;
  // A vector can initialize all its components to the
  // same value by using the Fill() method.
  initialValue.Fill( 0.0 );
  // Now the image buffer can be initialized with this
  // vector value.
  image->FillBuffer( initialValue );
  const ImageType::IndexType pixelIndex = {{27,29,37}}; //Position {X,Y,Z}
  // Software Guide : BeginLatex
  //
  // The Vector class inherits the operator \code{[]} from the
  // \doxygen{FixedArray} class. This makes it possible to access the
  // Vector's components using index notation.
  //
  // Software Guide : EndLatex
  // Software Guide : BeginCodeSnippet
  ImageType::PixelType   pixelValue;
  pixelValue[0] =  1.345;   // x component
  pixelValue[1] =  6.841;   // y component
  pixelValue[2] =  3.295;   // x component
  // Software Guide : EndCodeSnippet
  // Software Guide : BeginLatex
  //
  // We can now store this vector in one of the image pixels by defining an
  // index and invoking the \code{SetPixel()} method.
  //
  // Software Guide : EndLatex
  // Software Guide : BeginCodeSnippet
  image->SetPixel(   pixelIndex,   pixelValue  );
  // Software Guide : EndCodeSnippet
  // The GetPixel method can also be used to read Vectors
  // pixels from the image
  ImageType::PixelType value = image->GetPixel( pixelIndex );
  std::cout << value << std::endl;
  // Lets repeat that both \code{SetPixel()} and \code{GetPixel()} are
  // inefficient and should only be used for debugging purposes or for
  // implementing interactions with a graphical user interface such as
  // querying pixel value by clicking with the mouse.
  return EXIT_SUCCESS;
}

/*========================================================================= * * Copyright Insight Software Consortium * * 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 * * http://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 // // Many image processing tasks require images of non-scalar pixel type. A // typical example is an image of vectors. This is the image type required to // represent the gradient of a scalar image. The following code illustrates // how to instantiate and use an image whose pixels are of vector type. // // For convenience we use the \doxygen{Vector} class to define the pixel // type. The Vector class is intended to represent a geometrical vector in // space. It is not intended to be used as an array container like the // \href{http://www.sgi.com/tech/stl/Vector.html}{\code{std::vector}} in // \href{http://www.sgi.com/tech/stl/}{STL}. If you are interested in // containers, the \doxygen{VectorContainer} class may provide the // functionality you want. // // \index{itk::Vector} // \index{itk::Vector!header} // // // The first step is to include the header file of the Vector class. // // Software Guide : EndLatex // Software Guide : BeginCodeSnippet #include "itkVector.h" // Software Guide : EndCodeSnippet #include "itkImage.h" int main(int, char *[]) { // Software Guide : BeginLatex // // The Vector class is templated over the type used to represent // the coordinate in space and over the dimension of the space. In this example, // we want the vector dimension to match the image dimension, but this is by // no means a requirement. We could have defined a four-dimensional image // with three-dimensional vectors as pixels. // // \index{itk::Vector!Instantiation} // \index{itk::Vector!itk::Image} // \index{itk::Image!Vector pixel} // // Software Guide : EndLatex // Software Guide : BeginCodeSnippet typedef itk::Vector< float, 3 > PixelType; typedef itk::Image< PixelType, 3 > ImageType; // Software Guide : EndCodeSnippet // Then the image object can be created ImageType::Pointer image = ImageType::New(); // The image region should be initialized const ImageType::IndexType start = {{0,0,0}}; //First index at {X,Y,Z} const ImageType::SizeType size = {{200,200,200}}; //Size of {X,Y,Z} ImageType::RegionType region; region.SetSize( size ); region.SetIndex( start ); // Pixel data is allocated image->SetRegions( region ); image->Allocate(); // The image buffer is initialized to a particular value ImageType::PixelType initialValue; // A vector can initialize all its components to the // same value by using the Fill() method. initialValue.Fill( 0.0 ); // Now the image buffer can be initialized with this // vector value. image->FillBuffer( initialValue ); const ImageType::IndexType pixelIndex = {{27,29,37}}; //Position {X,Y,Z} // Software Guide : BeginLatex // // The Vector class inherits the operator \code{[]} from the // \doxygen{FixedArray} class. This makes it possible to access the // Vector's components using index notation. // // Software Guide : EndLatex // Software Guide : BeginCodeSnippet ImageType::PixelType pixelValue; pixelValue[0] = 1.345; // x component pixelValue[1] = 6.841; // y component pixelValue[2] = 3.295; // x component // Software Guide : EndCodeSnippet // Software Guide : BeginLatex // // We can now store this vector in one of the image pixels by defining an // index and invoking the \code{SetPixel()} method. // // Software Guide : EndLatex // Software Guide : BeginCodeSnippet image->SetPixel( pixelIndex, pixelValue ); // Software Guide : EndCodeSnippet // The GetPixel method can also be used to read Vectors // pixels from the image ImageType::PixelType value = image->GetPixel( pixelIndex ); std::cout << value << std::endl; // Lets repeat that both \code{SetPixel()} and \code{GetPixel()} are // inefficient and should only be used for debugging purposes or for // implementing interactions with a graphical user interface such as // querying pixel value by clicking with the mouse. return EXIT_SUCCESS; }

Answer 1

让我们先分析一下代码的重要部分：

下面：

typedef itk::Vector< float, 3 >       PixelType;
typedef itk::Image< PixelType, 3 >    ImageType;

说图像是一个3D图像。每个像素将成为3个浮点数的向量（例如，对PC-MRI有用）

示例中的下限是：

image->SetPixel(   pixelIndex,   pixelValue  );

实际上将矢量像素的值与pixelIndex中存储的坐标设置为pixelValue中的值。记住，坐标是3D。

现在，回答你的问题：

ITK“图像”只是数字数组。他们有你想要的意思。在该示例中，3D矩阵正在用向量填充。这就是你从例子中可以知道的全部内容。它们可以是颜色表示，矢量场的强度和方向，无论......

现在，如果你说“距离”，你的意思是“ 间距 ”，答案是否。不是你设置的间距。间距是图像中某个区域的属性，并且未在示例中的任何位置设置。

itk vector图像像素值

1 个答案: