Iterate Region in Image Without Write Access#
Synopsis#
Iterate over a region of an image (without write access).
Results#
Yinyang.png#
Output:
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Code#
C++#
#include "itkImage.h"
#include "itkImageFileReader.h"
#include "itkImageRegionConstIterator.h"
int
main(int argc, char * argv[])
{
if (argc < 2)
{
std::cerr << "Required: filename" << std::endl;
return EXIT_FAILURE;
}
using ImageType = itk::Image<unsigned char, 2>;
ImageType::Pointer image = itk::ReadImage<ImageType>(argv[1]);
ImageType::SizeType regionSize;
regionSize[0] = 5;
regionSize[1] = 4;
ImageType::IndexType regionIndex;
regionIndex[0] = 0;
regionIndex[1] = 0;
ImageType::RegionType region;
region.SetSize(regionSize);
region.SetIndex(regionIndex);
itk::ImageRegionConstIterator<ImageType> imageIterator(image, region);
// itk::ImageRegionConstIterator<ImageType> imageIterator(image,image->GetLargestPossibleRegion());
while (!imageIterator.IsAtEnd())
{
// Get the value of the current pixel
unsigned char val = imageIterator.Get();
std::cout << (int)val << std::endl;
++imageIterator;
}
return EXIT_SUCCESS;
}
Classes demonstrated#
-
template<typename TImage>
class ImageRegionConstIterator : public itk::ImageConstIterator<TImage> A multi-dimensional iterator templated over image type that walks a region of pixels.
The itk::ImageRegionConstIterator is optimized for iteration speed and is the first choice for iterative, pixel-wise operations on an image. ImageRegionIterator is the least specialized of the ITK image iterator classes. ImageRegionConstIterator is templated over the image type, and is constrained to walk only within the specified region and along a line parallel to one of the coordinate axes, “wrapping” to the next line as it reaches the boundary of the image. To walk the entire image, specify the region to be
image->GetRequestedRegion().ImageRegionConstIterator provides read-only access to image data. It is the base class for the read/write access ImageRegionIterator.
ImageRegionConstIterator is a multi-dimensional iterator, requiring more information be specified before the iterator can be used than conventional iterators. Whereas the std::vector::iterator from the STL only needs to be passed a pointer to establish the iterator, the multi-dimensional image iterator needs a pointer, the size of the buffer, the size of the region, the start index of the buffer, and the start index of the region. To gain access to this information, ImageRegionConstIterator holds a reference to the image over which it is traversing.
ImageRegionConstIterator assumes a particular layout of the image data. The is arranged in a 1D array as if it were [][][][slice][row][col] with Index[0] = col, Index[1] = row, Index[2] = slice, etc.
operator++ provides a simple syntax for walking around a region of a multidimensional image. operator++ iterates across a row, constraining the movement to within a region of image. When the iterator reaches the boundary of the region along a row, the iterator automatically wraps to the next row, starting at the first pixel in the row that is part of the region. This allows for simple processing loops of the form:
it = it.Begin(); for (; !it.IsAtEnd(); ++it) { *it += 100.0; }
See also
ImageConstIterator
See also
ConditionalConstIterator
See also
ConstNeighborhoodIterator
See also
ConstShapedNeighborhoodIterator
See also
ConstSliceIterator
See also
CorrespondenceDataStructureIterator
See also
FloodFilledFunctionConditionalConstIterator
See also
FloodFilledImageFunctionConditionalConstIterator
See also
FloodFilledImageFunctionConditionalIterator
See also
FloodFilledSpatialFunctionConditionalConstIterator
See also
FloodFilledSpatialFunctionConditionalIterator
See also
ImageConstIterator
See also
ImageConstIteratorWithIndex
See also
ImageIterator
See also
ImageIteratorWithIndex
See also
ImageLinearConstIteratorWithIndex
See also
ImageLinearIteratorWithIndex
See also
ImageRandomConstIteratorWithIndex
See also
ImageRandomIteratorWithIndex
See also
ImageRegionConstIterator
See also
ImageRegionConstIteratorWithIndex
See also
ImageRegionExclusionConstIteratorWithIndex
See also
ImageRegionExclusionIteratorWithIndex
See also
ImageRegionIterator
See also
ImageRegionIteratorWithIndex
See also
ImageRegionReverseConstIterator
See also
ImageRegionReverseIterator
See also
ImageReverseConstIterator
See also
ImageReverseIterator
See also
ImageSliceConstIteratorWithIndex
See also
ImageSliceIteratorWithIndex
See also
NeighborhoodIterator
See also
PathConstIterator
See also
PathIterator
See also
ShapedNeighborhoodIterator
See also
SliceIterator
See also
ImageConstIteratorWithIndex
See also
ImageRegionRange
See also
ImageRegionIndexRange
- MORE INFORMATION
For a complete description of the ITK Image Iterators and their API, please see the Iterators chapter in the ITK Software Guide. The ITK Software Guide is available in print and as a free .pdf download from https://www.itk.org.
- ITK Sphinx Examples:
Subclassed by itk::ImageRegionIterator< TOutputImage >, itk::ImageRegionIterator< OutputImageType >, itk::ImageRegionIterator< PosteriorsImageType >, itk::ImageRegionIterator< TClassifiedImage >, itk::ImageRegionIterator< LabelImageType >, itk::ImageRegionIterator< LabelStatusImageType >, itk::ImageRegionIterator< TImage >
