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| This example shows how to convert an RGBAImage to an RGBImage using ConvertPixelBuffer::Convert. ConvertPixelBuffer is used internally in itkImageFileReader to convert raw data into itk Images.
| | {{warning|1=The media wiki content on this page is no longer maintained. The examples presented on the https://itk.org/Wiki/* pages likely require ITK version 4.13 or earlier releases. In many cases, the examples on this page no longer conform to the best practices for modern ITK versions. |
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| '''NOTE:''' This example accesses internal pointers for pixel container data. If you think you need to use this approach, be extremely careful. Since you are dealing with raw pointers, you must be certain that the memory organization for the input and output is compatible in C++ type and dimensions.
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| A safer approach uses itkCastImageFilter as illustrated in this example: [[ITK/Examples/ImageProcessing/CastImageFilter|CastImageFilter]]
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| ==ConvertPixelBuffer.cxx==
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| <source lang="cpp">
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| #include "itkRGBPixel.h"
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| #include "itkRGBAPixel.h"
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| #include "itkImage.h"
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| #include "itkDefaultConvertPixelTraits.h"
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| #include "itkConvertPixelBuffer.h"
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| #include "itkImageRandomConstIteratorWithIndex.h"
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| int main(int argc, char* argv[])
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| {
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| const int xDimension = 200;
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| const int yDimension = 100;
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| typedef unsigned char ComponentType;
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| typedef itk::RGBPixel<ComponentType> RGBPixelType;
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| typedef itk::RGBAPixel<ComponentType> RGBAPixelType;
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| typedef itk::Image< RGBPixelType, 2 > RGBImageType;
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| typedef itk::Image< RGBAPixelType, 2 > RGBAImageType;
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| typedef itk::DefaultConvertPixelTraits< RGBPixelType >
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| TraitsType;
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| typedef itk::ConvertPixelBuffer< ComponentType, RGBPixelType, TraitsType >
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| RGBAConverterType;
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| RGBImageType::Pointer rgbImg = RGBImageType::New();
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| RGBAImageType::Pointer rgbaImg = RGBAImageType::New();
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| // Create the two images
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| // RGBAImage
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| RGBAImageType::IndexType rgbaStart;
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| rgbaStart[0] = 0;
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| rgbaStart[1] = 0;
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| RGBAImageType::SizeType rgbaSize;
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| rgbaSize[0] = xDimension;
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| rgbaSize[1] = yDimension;
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| itk::ImageRegion<2> rgbaRegion(rgbaStart,rgbaSize);
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| rgbaImg->SetRegions(rgbaRegion);
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| rgbaImg->Allocate();
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| RGBAPixelType rgbaDefault;
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| rgbaDefault[0] = 127;
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| rgbaDefault[1] = 100;
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| rgbaDefault[2] = 230;
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| rgbaDefault[3] = 255;
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| rgbaImg->FillBuffer(rgbaDefault);
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| // RGBImage
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| RGBImageType::IndexType rgbStart = rgbaStart;
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| RGBImageType::SizeType rgbSize = rgbaSize;
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| itk::ImageRegion<2> rgbRegion = rgbaRegion;
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| rgbImg->SetRegions(rgbRegion);
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| rgbImg->Allocate();
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| size_t numberOfPixels =
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| rgbImg->GetLargestPossibleRegion().GetNumberOfPixels();
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| // Convert a raw buffer to a buffer of pixel types
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| RGBAConverterType::Convert(
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| static_cast<ComponentType *>(rgbaImg->GetPixelContainer()->GetBufferPointer()->GetDataPointer()),
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| rgbaImg->GetNumberOfComponentsPerPixel(),
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| (rgbImg->GetPixelContainer()->GetBufferPointer()),
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| numberOfPixels);
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| // Check a few random values
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| itk::ImageRandomConstIteratorWithIndex<RGBImageType>
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| rgbIterator(rgbImg, rgbImg->GetLargestPossibleRegion());
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| rgbIterator.SetNumberOfSamples(numberOfPixels / 10);
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| rgbIterator.GoToBegin();
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| while(!rgbIterator.IsAtEnd())
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| {
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| if (rgbImg->GetPixel(rgbIterator.GetIndex())[0] !=
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| rgbaImg->GetPixel(rgbIterator.GetIndex())[0] ||
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| rgbImg->GetPixel(rgbIterator.GetIndex())[1] !=
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| rgbaImg->GetPixel(rgbIterator.GetIndex())[1] ||
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| rgbImg->GetPixel(rgbIterator.GetIndex())[2] !=
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| rgbaImg->GetPixel(rgbIterator.GetIndex())[2])
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| {
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| std::cout << "Copy failed for index " << rgbIterator.GetIndex()
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| << " got " << rgbImg->GetPixel(rgbIterator.GetIndex())
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| << " but expected " << rgbaImg->GetPixel(rgbIterator.GetIndex())
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| << std::endl;
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| }
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| ++rgbIterator;
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| }
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| return EXIT_SUCCESS;
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| }
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| </source>
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| {{ITKCMakeLists|{{SUBPAGENAME}}}}
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