Random Selection of Pixels From Region#

Synopsis#

Randomly select pixels from a region of an image.

Results#

Output:

[4, 2]
[1, 1]
[1, 3]
[4, 0]
[3, 0]
[4, 3]
[1, 0]
[1, 1]
[4, 2]
[4, 2]
[1, 2]
[2, 1]
[1, 2]
[2, 3]
[2, 3]
[4, 1]
[4, 2]
[3, 1]
[2, 2]
[2, 2]
[1, 1]
[2, 2]
[1, 1]
[1, 1]
[1, 0]
[3, 1]
[2, 1]
[4, 0]
[2, 2]
[4, 1]
[0, 2]
[2, 1]
[0, 2]
[1, 0]
[1, 0]
[2, 3]
[1, 1]
[1, 3]
[0, 1]
[3, 0]
[4, 2]
[4, 0]
[3, 1]
[0, 1]
[0, 3]
[0, 0]
[1, 2]
[3, 2]
[2, 0]
[2, 2]
[1, 1]
[3, 2]
[1, 1]
[2, 1]
[2, 1]
[4, 2]
[1, 3]
[4, 1]
[0, 3]
[1, 2]
[4, 3]
[0, 0]
[2, 1]
[1, 0]
[4, 3]
[4, 3]
[2, 3]
[2, 3]
[0, 3]
[1, 2]
[1, 3]
[2, 0]
[1, 0]
[2, 3]
[3, 3]
[3, 2]
[0, 0]
[3, 3]
[1, 2]
[1, 0]
[3, 0]
[3, 3]
[4, 0]
[1, 2]
[0, 2]
[1, 3]
[3, 3]
[1, 1]
[0, 3]
[0, 0]
[0, 2]
[0, 2]
[2, 2]
[2, 2]
[4, 1]
[2, 2]
[1, 1]
[1, 0]
[4, 1]
[1, 0]
[3, 1]
[4, 3]
[0, 0]
[3, 2]
[1, 2]
[1, 2]
[2, 3]
[4, 2]
[2, 2]
[3, 0]
[0, 3]
[2, 2]
[1, 1]
[2, 3]
[4, 0]
[0, 3]
[4, 2]
[3, 2]
[3, 3]
[1, 2]
[4, 3]
[0, 0]
[1, 3]
[0, 0]
[4, 2]
[0, 2]
[0, 2]
[0, 3]
[4, 2]
[4, 2]
[4, 2]
[3, 2]
[4, 0]
[0, 0]
[0, 1]
[3, 0]
[0, 0]
[0, 0]
[0, 0]
[0, 0]
[4, 2]
[1, 2]
[0, 3]
[3, 3]
[4, 2]
[2, 2]
[2, 2]
[3, 3]
[1, 2]
[2, 1]
[0, 2]
[1, 2]
[4, 0]
[4, 3]
[3, 3]
[1, 2]
[0, 1]
[3, 2]
[0, 2]
[4, 1]
[1, 2]
[3, 0]
[4, 3]
[1, 2]
[2, 2]
[2, 3]
[0, 0]
[2, 3]
[4, 1]
[4, 2]
[4, 2]
[1, 2]
[3, 3]
[1, 3]
[0, 2]
[3, 2]
[3, 0]
[2, 3]
[4, 2]
[2, 3]
[4, 2]
[4, 0]
[2, 0]
[1, 0]
[1, 2]
[1, 0]
[3, 2]
[0, 0]
[3, 1]
[4, 3]
[0, 3]
[0, 2]
[2, 0]
[4, 2]
[3, 2]
[1, 0]
[1, 0]
[4, 0]
[1, 2]
[0, 2]

Code#

C++#

#include "itkImage.h"
#include "itkImageRandomConstIteratorWithIndex.h"

int
main()
{
  using ImageType = itk::Image<unsigned char, 2>;
  auto image = ImageType::New();

  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);

  image->SetRegions(region);
  image->Allocate();
  image->FillBuffer(0);

  itk::ImageRandomConstIteratorWithIndex<ImageType> imageIterator(image, image->GetLargestPossibleRegion());
  imageIterator.SetNumberOfSamples(200);
  imageIterator.GoToBegin();

  while (!imageIterator.IsAtEnd())
  {
    std::cout << imageIterator.GetIndex() << std::endl;

    ++imageIterator;
  }

  return EXIT_SUCCESS;
}

Classes demonstrated#

template<typename TImage> class ImageRandomConstIteratorWithIndex : public itk::ImageConstIteratorWithIndex<TImage>

A multi-dimensional image iterator that visits a random set of pixels within an image region.

ImageRandomConstIteratorWithIndex is a multi-dimensional iterator class that is templated over image type. ImageRandomConstIteratorWithIndex is constrained to walk only within the specified region. It samples random pixel positions at each increment or decrement.

ImageRandomConstIteratorWithIndex 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.

The operator++ method provides a simple syntax for walking around a region of a multidimensional image. operator++ performs a jump to a random position within the specified image region. This is designed to facilitate the extraction of random samples from the image.

This is the typical use of this iterator in a loop:

ImageRandomConstIteratorWithIndex<ImageType> it( image, image->GetRequestedRegion() );

it.SetNumberOfSamples(200);
it.GoToBegin();
while( !it.IsAtEnd() )
{
  it.Get();
  ++it;  // here it jumps to another random position inside the region
 }

or

ImageRandomConstIteratorWithIndex<ImageType> it( image, image->GetRequestedRegion() );

it.SetNumberOfSamples(200);
it.GoToEnd();
while( !it.IsAtBegin() )
{
  it.Get();
  --it;  // here it jumps to another random position inside the region
 }

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

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: