itk中创建一个图像数据

关于数据的创建，有几种不同的方法可以用。itk提供了一个专业的类：itkImportImageFilter。它实现了从N维数组转到一个itk类型的image数据。不过方法和之前文《itk中的基本图像操作》中的流程大同小异，分别设置了图像的4大要素：SetRegion（区域），SetOrigin（原点），SetSpacing（间距），SetImportPointer（数据）。这种方法的使用环境更适用于自定义数组数据结构与itk算法之间做接口。

详细如下：

  typedef unsigned char   PixelType;const unsigned int Dimension = 3;typedef itk::Image< PixelType, Dimension > ImageType;typedef itk::ImportImageFilter< PixelType, Dimension >   ImportFilterType;ImportFilterType::Pointer importFilter = ImportFilterType::New();ImportFilterType::SizeType  size; size[0]  = 200;  // size along Xsize[1]  = 200;  // size along Ysize[2]  = 200;  // size along ZImportFilterType::IndexType start;start.Fill( 0 );ImportFilterType::RegionType region;region.SetIndex( start );region.SetSize(  size  );importFilter->SetRegion( region );double origin[ Dimension ];origin[0] = 0.0;    // X coordinateorigin[1] = 0.0;    // Y coordinateorigin[2] = 0.0;    // Z coordinateimportFilter->SetOrigin( origin );double spacing[ Dimension ];spacing[0] = 1.0;    // along X directionspacing[1] = 1.0;    // along Y directionspacing[2] = 1.0;    // along Z directionimportFilter->SetSpacing( spacing );const unsigned int numberOfPixels =  size[0] * size[1] * size[2];PixelType * localBuffer = new PixelType[ numberOfPixels ];const double radius = 80.0;const double radius2 = radius * radius;PixelType * it = localBuffer;for(unsigned int z=0; z < size[2]; z++){const double dz = static_cast<double>( z ) - static_cast<double>(size[2])/2.0;for(unsigned int y=0; y < size[1]; y++){const double dy = static_cast<double>( y ) - static_cast<double>(size[1])/2.0;for(unsigned int x=0; x < size[0]; x++){const double dx = static_cast<double>( x ) - static_cast<double>(size[0])/2.0;const double d2 = dx*dx + dy*dy + dz*dz;*it++ = ( d2 < radius2 ) ? 255 : 0; //画一个球 三木运算符}}}const bool importImageFilterWillOwnTheBuffer = true;importFilter->SetImportPointer( localBuffer, numberOfPixels,importImageFilterWillOwnTheBuffer );output_data = importFilter->GetOutput()

类的源码中有一个关键函数（这个方法的精髓在这里）：

SetImportPointer(TPixel *ptr（输入数组的指针）, unsigned long num（像素点个数）, bool LetFilterManageMemory（让过滤器设置内存？？？没看懂呢？）)
{if (ptr != m_ImportPointer){if (m_ImportPointer && m_FilterManageMemory){delete [] m_ImportPointer;}m_ImportPointer = ptr;this->Modified();}m_FilterManageMemory = LetFilterManageMemory;m_Size = num;
}

数据生成函数：

GenerateData()
{// Normally, GenerateData() allocates memory.  However, the application// provides the memory for this filter via the SetImportPointer() method.// Therefore, this filter does not call outputPtr->Allocate().// get pointer to the outputOutputImagePointer outputPtr = this->GetOutput();// the output buffer size is set to the size specified by the user via the// SetRegion() method.outputPtr->SetBufferedRegion( outputPtr->GetLargestPossibleRegion() );// pass the pointer down to the container during each Update() since// a call to Initialize() causes the container to forget the// pointer.  Note that we tell the container NOT to manage the// memory itself.  This filter will properly manage the memory (as// opposed to the container) if the user wants it to.outputPtr->GetPixelContainer()->SetImportPointer( m_ImportPointer,m_Size, false );
}

用户需求，产品需求，技术需求；

基本需求，期望需求，兴奋需求；

紧急重要，紧急不重要，不紧急重要，不紧急不重要；

其实不多数事情都能通过产品需求分析使其量化，参数化，这样才能在做决策的时候尽量客观，使风险降到最低。

科学的管理方法是很有用的。

参考文献：
1.https://itk.org/Wiki/ITK/Examples/IO/ImportImageFilter
2.http://blog.csdn.net/ameyume/article/details/6326278

itk中创建一个图像数据

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