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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 itkParabolicUtils_h
#define itkParabolicUtils_h
#include <itkArray.h>
#include "itkProgressReporter.h"
namespace itk
{
template <typename LineBufferType, typename RealType, typename TInputPixel, bool doDilate>
void
DoLine(LineBufferType & LineBuf, LineBufferType & tmpLineBuf, const RealType magnitude)
{
static constexpr RealType extreme =
doDilate ? NumericTraits<TInputPixel>::NonpositiveMin() : NumericTraits<TInputPixel>::max();
// contact point algorithm
long koffset = 0, newcontact = 0; // how far away the search starts.
const long LineLength = LineBuf.size();
// negative half of the parabola
for (long pos = 0; pos < LineLength; ++pos)
{
RealType BaseVal = extreme; // the base value for comparison
for (long krange = koffset; krange <= 0; ++krange)
{
// difference needs to be paramaterised
RealType T = LineBuf[pos + krange] - magnitude * krange * krange;
// switch on template parameter - hopefully gets optimized away.
if (doDilate ? (T >= BaseVal) : (T <= BaseVal))
{
BaseVal = T;
newcontact = krange;
}
}
tmpLineBuf[pos] = BaseVal;
koffset = newcontact - 1;
}
// positive half of parabola
koffset = newcontact = 0;
for (long pos = LineLength - 1; pos >= 0; pos--)
{
RealType BaseVal = extreme; // the base value for comparison
for (long krange = koffset; krange >= 0; krange--)
{
RealType T = tmpLineBuf[pos + krange] - magnitude * krange * krange;
if (doDilate ? (T >= BaseVal) : (T <= BaseVal))
{
BaseVal = T;
newcontact = krange;
}
}
LineBuf[pos] = BaseVal;
koffset = newcontact + 1;
}
}
template <typename TInIter,
typename TOutIter,
typename RealType,
typename TInputPixel,
typename OutputPixelType,
bool doDilate>
void
doOneDimension(TInIter & inputIterator,
TOutIter & outputIterator,
ProgressReporter & progress,
const long LineLength,
const unsigned direction,
const bool m_UseImageSpacing,
const RealType image_scale,
const RealType Sigma)
{
// using LineBufferType = typename std::vector<RealType>;
// message from M.Starring suggested performance gain using Array
// instead of std::vector.
using LineBufferType = typename itk::Array<RealType>;
RealType iscale = 1.0;
if (m_UseImageSpacing)
{
iscale = image_scale;
}
constexpr int magnitudeSign = doDilate ? 1 : -1;
const RealType magnitude = magnitudeSign * 1.0 / (2.0 * Sigma / (iscale * iscale));
LineBufferType LineBuf(LineLength);
LineBufferType tmpLineBuf(LineLength);
inputIterator.SetDirection(direction);
outputIterator.SetDirection(direction);
inputIterator.GoToBegin();
outputIterator.GoToBegin();
while (!inputIterator.IsAtEnd() && !outputIterator.IsAtEnd())
{
// process this direction
// fetch the line into the buffer - this methodology is like
// the gaussian filters
unsigned int i = 0;
while (!inputIterator.IsAtEndOfLine())
{
LineBuf[i++] = static_cast<RealType>(inputIterator.Get());
++inputIterator;
}
DoLine<LineBufferType, RealType, TInputPixel, doDilate>(LineBuf, tmpLineBuf, magnitude);
// copy the line back
unsigned int j = 0;
while (!outputIterator.IsAtEndOfLine())
{
outputIterator.Set(static_cast<OutputPixelType>(LineBuf[j++]));
++outputIterator;
}
// now onto the next line
inputIterator.NextLine();
outputIterator.NextLine();
progress.CompletedPixel();
}
}
} // namespace itk
#endif
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