itk矢量圖像像素值

Question

我已經找到了這個itk矢量圖像的例子，我不明白矢量像素類型的每個組件的含義。
例如，代碼行pixelValue [0] = 1.345;分量X是指圖像矩陣內的下一個像素的灰度值或距離？

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* Copyright Insight Software Consortium 
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* 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 
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* 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 
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*=========================================================================*/ 
// 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

讓我們先分析代碼的重要部分：

這裏：

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

說，圖像是goint是一個3D圖像。每個像素將是3個浮點數的向量（用於PC-MRI很有用，例如）

下在你有這樣的例子：

image->SetPixel( pixelIndex, pixelValue ); 

至極實際上是設置矢量像素與價值存儲在pixelIndex中的座標值爲pixelValue中的值。記住，座標是3D。現在

，回答你的問題：

ITK 「圖像」 僅僅是數字數組。他們有你想要的意思。在這個例子中，一個3D矩陣正被向量填充。這就是你可能從這個例子中知道的一切。它們可以是彩色的表示，矢量磁場的強度和方向，無論...

現在，如果當你說「距離」你的意思是「間距」答案是沒有。是不是你設置的間距。間距是圖像中某個區域的屬性，並且不會在您的示例中的任何位置設置。