Create Forward Difference Kernel

Synopsis

Create a forward difference kernel.

Results

Output:

Size: [3, 3]
Neighborhood:
Radius:[1, 1]
Size:[3, 3]
DataBuffer:NeighborhoodAllocator { this = 0x7ffee23339e0, begin = 0x7fd6921a8f60, size=9 }
[-1, -1] 0
[0, -1] 0
[1, -1] 0
[-1, 0] 0
[0, 0] -1
[1, 0] 1
[-1, 1] 0
[0, 1] 0
[1, 1] 0

Code

C++

#include <itkForwardDifferenceOperator.h>

int
main(int, char *[])
{
  using ForwardDifferenceOperatorType = itk::ForwardDifferenceOperator<float, 2>;
  ForwardDifferenceOperatorType forwardDifferenceOperator;
  forwardDifferenceOperator.SetDirection(0); // Create the operator for the X axis derivative
  itk::Size<2> radius;
  radius.Fill(1);
  forwardDifferenceOperator.CreateToRadius(radius);

  std::cout << "Size: " << forwardDifferenceOperator.GetSize() << std::endl;

  std::cout << forwardDifferenceOperator << std::endl;

  for (unsigned int i = 0; i < 9; i++)
  {
    std::cout << forwardDifferenceOperator.GetOffset(i) << " " << forwardDifferenceOperator.GetElement(i) << std::endl;
  }
  return EXIT_SUCCESS;
}

Python

#!/usr/bin/env python

import itk

forwardDifferenceOperator = itk.ForwardDifferenceOperator[itk.F, 2]()
forwardDifferenceOperator.SetDirection(0)  # Create the operator for the X axis derivative
radius = itk.Size[2]()
radius.Fill(1)
forwardDifferenceOperator.CreateToRadius(radius)

print("Size: " + str(forwardDifferenceOperator.GetSize()))

print(forwardDifferenceOperator)

for i in range(9):
    print(str(forwardDifferenceOperator.GetOffset(i)) + " " + str(forwardDifferenceOperator.GetElement(i)))

Classes demonstrated

template<typename TPixel, unsigned int VDimension = 2, typename TAllocator = NeighborhoodAllocator<TPixel>>
class ForwardDifferenceOperator : public itk::NeighborhoodOperator<TPixel, VDimension, TAllocator>

Operator whose inner product with a neighborhood returns a “half” derivative at the center of the neighborhood.

ForwardDifferenceOperator uses forward differences i.e. F(x+1) - F(x) to calculate a “half” derivative useful, among other things, in solving differential equations. It is a directional NeighborhoodOperator that should be applied to a Neighborhood using the inner product.

Note

ForwardDifferenceOperator does not have any user-declared “special member function”, following the C++ Rule of Zero: the compiler will generate them if necessary.

ITK Sphinx Examples:

See itk::ForwardDifferenceOperator for additional documentation.