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/*=========================================================================
*
* Copyright Insight Software Consortium
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0.txt
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
*=========================================================================*/
#ifndef itkDifferenceOfGaussiansGradientImageFilter_hxx
#define itkDifferenceOfGaussiansGradientImageFilter_hxx
#include <cmath>
#include "itkProgressReporter.h"
#include "itkDifferenceOfGaussiansGradientImageFilter.h"
#include "itkImageRegionIterator.h"
namespace itk
{
template< typename TInputImage, typename TDataType >
DifferenceOfGaussiansGradientImageFilter< TInputImage, TDataType >
::DifferenceOfGaussiansGradientImageFilter()
{
itkDebugMacro(<< "DifferenceOfGaussiansGradientImageFilter::DifferenceOfGaussiansGradientImageFilter() called");
m_Width = 2;
}
template< typename TInputImage, typename TDataType >
void
DifferenceOfGaussiansGradientImageFilter< TInputImage, TDataType >
::GenerateData()
{
itkDebugMacro(<< "DifferenceOfGaussiansGradientImageFilter::GenerateData() called");
// Get the input and output pointers
typename Superclass::InputImagePointer inputPtr =
const_cast< TInputImage * >( this->GetInput(0) );
typename Superclass::OutputImagePointer outputPtr = this->GetOutput(0);
// Make sure we're getting everything
inputPtr->SetRequestedRegionToLargestPossibleRegion();
// How big is the input image?
typename TInputImage::SizeType size = inputPtr->GetLargestPossibleRegion().GetSize();
// Create a region object native to the output image type
OutputImageRegionType outputRegion;
// Resize the output region
outputRegion.SetSize(size);
// Set the largest legal region size (i.e. the size of the whole image)
// to what we just defined
outputPtr->SetBufferedRegion(outputRegion);
outputPtr->Allocate();
// Create a progress reporter
ProgressReporter progress( this, 0, outputPtr->GetRequestedRegion().GetNumberOfPixels() );
// Create an iterator that will walk the output region
typedef ImageRegionIterator< TOutputImage > OutputIterator;
OutputIterator outIt = OutputIterator( outputPtr,
outputPtr->GetRequestedRegion() );
// Define a few indices that will be used to translate from an input pixel
// to an output pixel
typename TOutputImage::IndexType outputIndex;
typename TOutputImage::IndexType upperIndex;
typename TOutputImage::IndexType lowerIndex;
// walk the output image, and sample the input image
for (; !outIt.IsAtEnd(); ++outIt )
{
// determine the index of the output pixel
outputIndex = outIt.GetIndex();
// is the current index an acceptable distance from the edges
// of the image?
bool isValidGrad = true;
for ( unsigned int i = 0; i < NDimensions; ++i )
{
const int width = static_cast< int >( m_Width );
const int sizeDifference =
static_cast< int >( size.m_Size[i] ) - width;
if ( !( ( outputIndex[i] < sizeDifference )
&& ( outputIndex[i] >= width ) ) )
{
isValidGrad = false;
}
}
if ( isValidGrad )
{
// We're in a safe position, so calculate the gradient for
// each dimension
for ( unsigned int i = 0; i < NDimensions; i++ )
{
// Build the indices for each pixel
for ( unsigned int j = 0; j < NDimensions; j++ )
{
if ( j == i )
{
upperIndex[j] = outputIndex[j] + static_cast< IndexValueType >( m_Width );
lowerIndex[j] = outputIndex[j] - static_cast< IndexValueType >( m_Width );
}
else
{
upperIndex[j] = outputIndex[j];
lowerIndex[j] = outputIndex[j];
}
}
// Remember, output type is a covariant vector of TDataType
outputPtr->GetPixel(outputIndex)[i] =
inputPtr->GetPixel(upperIndex) - inputPtr->GetPixel(lowerIndex);
}
}
else // We're not in a safe position, gradient is zero
{
for ( unsigned int i = 0; i < NDimensions; ++i )
{
outputPtr->GetPixel(outputIndex)[i] = 0.0;
}
}
progress.CompletedPixel();
}
itkDebugMacro(<< "DifferenceOfGaussiansGradientImageFilter::GenerateData() finished");
}
template< typename TInputImage, typename TDataType >
void
DifferenceOfGaussiansGradientImageFilter< TInputImage, TDataType >
::PrintSelf(std::ostream & os, Indent indent) const
{
Superclass::PrintSelf(os, indent);
os << indent << "Width is " << m_Width << std::endl;
}
} // end namespace
#endif
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