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Resampling Convolution Filters | ![]() |
Functions | |
template<... > | |
void | pyramidExpandBurtFilter (...) |
Two-fold up-sampling for image pyramid reconstruction. | |
template<class Image , class Alloc > | |
void | pyramidExpandBurtLaplacian (ImagePyramid< Image, Alloc > &pyramid, int fromLevel, int toLevel, double centerValue=0.4) |
Reconstruct a Laplacian pyramid. | |
template<... > | |
void | pyramidReduceBurtFilter (...) |
Two-fold down-sampling for image pyramid construction. | |
template<class Image , class Alloc > | |
void | pyramidReduceBurtLaplacian (ImagePyramid< Image, Alloc > &pyramid, int fromLevel, int toLevel, double centerValue=0.4) |
Create a Laplacian pyramid. | |
template<... > | |
void | resamplingConvolveImage (...) |
Apply two separable resampling filters successively, the first in x-direction, the second in y-direction. | |
template<... > | |
void | resamplingConvolveLine (...) |
Performs a 1-dimensional resampling convolution of the source signal using the given set of kernels. | |
template<... > | |
void | resamplingConvolveX (...) |
Apply a resampling filter in the x-direction. | |
template<... > | |
void | resamplingConvolveY (...) |
Apply a resampling filter in the y-direction. |
These functions implement the convolution operation when the source and target images have different sizes. This is realized by accessing a continous kernel at the appropriate non-integer positions. The technique is, for example, described in D. Schumacher: General Filtered Image Rescaling, in: Graphics Gems III, Academic Press, 1992.
void vigra::resamplingConvolveLine | ( | ... | ) |
Performs a 1-dimensional resampling convolution of the source signal using the given set of kernels.
This function is mainly used internally: It is called for each dimension of a higher dimensional array in order to perform a separable resize operation.
Declaration:
#include <vigra/resampling_convolution.hxx>
namespace vigra { template <class SrcIter, class SrcAcc, class DestIter, class DestAcc, class KernelArray, class Functor> void resamplingConvolveLine(SrcIter s, SrcIter send, SrcAcc src, DestIter d, DestIter dend, DestAcc dest, KernelArray const & kernels, Functor mapTargetToSourceCoordinate) }
void vigra::resamplingConvolveX | ( | ... | ) |
Apply a resampling filter in the x-direction.
This function implements a convolution operation in x-direction (i.e. applies a 1D filter to every row) where the width of the source and destination images differ. This is typically used to avoid aliasing if the image is scaled down, or to interpolate smoothly if the image is scaled up. The target coordinates are transformed into source coordinates by
xsource = (xtarget - offset) / samplingRatio
The samplingRatio
and offset
must be given as vigra::Rational in order to avoid rounding errors in this transformation. It is required that for all pixels of the target image, xsource
remains within the range of the source image (i.e. 0 <= xsource <= sourceWidth-1
. Since xsource
is in general not an integer, the kernel
must be a functor that can be accessed at arbitrary (double
) coordinates. It must also provide a member function radius()
which specifies the support (non-zero interval) of the kernel. VIGRA already provides a number of suitable functors, e.g. vigra::Gaussian, vigra::BSpline vigra::CatmullRomSpline, and vigra::CoscotFunction. The function resizeImageSplineInterpolation() is implemented by means resamplingConvolveX() and resamplingConvolveY().
Declarations:
pass arguments explicitly:
namespace vigra { template <class SrcIter, class SrcAcc, class DestIter, class DestAcc, class Kernel> void resamplingConvolveX(SrcIter sul, SrcIter slr, SrcAcc src, DestIter dul, DestIter dlr, DestAcc dest, Kernel const & kernel, Rational<int> const & samplingRatio, Rational<int> const & offset); }
use argument objects in conjunction with Argument Object Factories :
namespace vigra { template <class SrcIter, class SrcAcc, class DestIter, class DestAcc, class Kernel> void resamplingConvolveX(triple<SrcIter, SrcIter, SrcAcc> src, triple<DestIter, DestIter, DestAcc> dest, Kernel const & kernel, Rational<int> const & samplingRatio, Rational<int> const & offset); }
Usage:
#include <vigra/resampling_convolution.hxx>
Rational<int> ratio(2), offset(0); FImage src(w,h), dest(rational_cast<int>(ratio*w), h); float sigma = 2.0; Gaussian<float> smooth(sigma); ... // simpultaneously enlarge and smooth source image resamplingConvolveX(srcImageRange(src), destImageRange(dest), smooth, ratio, offset);
Required Interface:
Kernel kernel; int kernelRadius = kernel.radius(); double x = ...; // must be <= radius() double value = kernel(x);
void vigra::resamplingConvolveY | ( | ... | ) |
Apply a resampling filter in the y-direction.
This function implements a convolution operation in y-direction (i.e. applies a 1D filter to every column) where the height of the source and destination images differ. This is typically used to avoid aliasing if the image is scaled down, or to interpolate smoothly if the image is scaled up. The target coordinates are transformed into source coordinates by
ysource = (ytarget - offset) / samplingRatio
The samplingRatio
and offset
must be given as vigra::Rational in order to avoid rounding errors in this transformation. It is required that for all pixels of the target image, ysource
remains within the range of the source image (i.e. 0 <= ysource <= sourceHeight-1
. Since ysource
is in general not an integer, the kernel
must be a functor that can be accessed at arbitrary (double
) coordinates. It must also provide a member function radius()
which specifies the support (non-zero interval) of the kernel. VIGRA already provides a number of suitable functors, e.g. vigra::Gaussian, vigra::BSpline vigra::CatmullRomSpline, and vigra::CoscotFunction. The function resizeImageSplineInterpolation() is implemented by means resamplingConvolveX() and resamplingConvolveY().
Declarations:
pass arguments explicitly:
namespace vigra { template <class SrcIter, class SrcAcc, class DestIter, class DestAcc, class Kernel> void resamplingConvolveY(SrcIter sul, SrcIter slr, SrcAcc src, DestIter dul, DestIter dlr, DestAcc dest, Kernel const & kernel, Rational<int> const & samplingRatio, Rational<int> const & offset); }
use argument objects in conjunction with Argument Object Factories :
namespace vigra { template <class SrcIter, class SrcAcc, class DestIter, class DestAcc, class Kernel> void resamplingConvolveY(triple<SrcIter, SrcIter, SrcAcc> src, triple<DestIter, DestIter, DestAcc> dest, Kernel const & kernel, Rational<int> const & samplingRatio, Rational<int> const & offset); }
Usage:
#include <vigra/resampling_convolution.hxx>
Rational<int> ratio(2), offset(0); FImage src(w,h), dest(w, rational_cast<int>(ratio*h)); float sigma = 2.0; Gaussian<float> smooth(sigma); ... // simpultaneously enlarge and smooth source image resamplingConvolveY(srcImageRange(src), destImageRange(dest), smooth, ratio, offset);
Required Interface:
Kernel kernel; int kernelRadius = kernel.radius(); double y = ...; // must be <= radius() double value = kernel(y);
void vigra::resamplingConvolveImage | ( | ... | ) |
Apply two separable resampling filters successively, the first in x-direction, the second in y-direction.
This function is a shorthand for the concatenation of a call to resamplingConvolveX() and resamplingConvolveY() with the given kernels. See there for detailed documentation.
Declarations:
pass arguments explicitly:
namespace vigra { template <class SrcIterator, class SrcAccessor, class DestIterator, class DestAccessor, class KernelX, class KernelY> void resamplingConvolveImage(SrcIterator sul,SrcIterator slr, SrcAccessor src, DestIterator dul, DestIterator dlr, DestAccessor dest, KernelX const & kx, Rational<int> const & samplingRatioX, Rational<int> const & offsetX, KernelY const & ky, Rational<int> const & samplingRatioY, Rational<int> const & offsetY); }
use argument objects in conjunction with Argument Object Factories :
namespace vigra { template <class SrcIterator, class SrcAccessor, class DestIterator, class DestAccessor, class KernelX, class KernelY> void resamplingConvolveImage(triple<SrcIterator, SrcIterator, SrcAccessor> src, triple<DestIterator, DestIterator, DestAccessor> dest, KernelX const & kx, Rational<int> const & samplingRatioX, Rational<int> const & offsetX, KernelY const & ky, Rational<int> const & samplingRatioY, Rational<int> const & offsetY); }
Usage:
#include <vigra/resampling_convolution.hxx>
Rational<int> xratio(2), yratio(3), offset(0); FImage src(w,h), dest(rational_cast<int>(xratio*w), rational_cast<int>(yratio*h)); float sigma = 2.0; Gaussian<float> smooth(sigma); ... // simpultaneously enlarge and smooth source image resamplingConvolveImage(srcImageRange(src), destImageRange(dest), smooth, xratio, offset, smooth, yratio, offset);
void vigra::pyramidReduceBurtFilter | ( | ... | ) |
Two-fold down-sampling for image pyramid construction.
Sorry, no detailedDocumentation() available yet.
Declarations:
#include <vigra/resampling_convolution.hxx>
Namespace: vigra
pass arguments explicitly:
namespace vigra { template <class SrcIterator, class SrcAccessor, class DestIterator, class DestAccessor> void pyramidReduceBurtFilter(SrcIterator sul, SrcIterator slr, SrcAccessor src, DestIterator dul, DestIterator dlr, DestAccessor dest, double centerValue = 0.4); }
use argument objects in conjunction with Argument Object Factories :
namespace vigra { template <class SrcIterator, class SrcAccessor, class DestIterator, class DestAccessor> void pyramidReduceBurtFilter(triple<SrcIterator, SrcIterator, SrcAccessor> src, triple<DestIterator, DestIterator, DestAccessor> dest, double centerValue = 0.4); }
use a vigra::ImagePyramid :
namespace vigra { template <class Image, class Alloc> void pyramidReduceBurtFilter(ImagePyramid<Image, Alloc> & pyramid, int fromLevel, int toLevel, double centerValue = 0.4); }
void vigra::pyramidExpandBurtFilter | ( | ... | ) |
Two-fold up-sampling for image pyramid reconstruction.
Sorry, no detailedDocumentation() available yet.
Declarations:
#include <vigra/resampling_convolution.hxx>
Namespace: vigra
pass arguments explicitly:
namespace vigra { template <class SrcIterator, class SrcAccessor, class DestIterator, class DestAccessor> void pyramidExpandBurtFilter(SrcIterator sul, SrcIterator slr, SrcAccessor src, DestIterator dul, DestIterator dlr, DestAccessor dest, double centerValue = 0.4); }
use argument objects in conjunction with Argument Object Factories :
namespace vigra { template <class SrcIterator, class SrcAccessor, class DestIterator, class DestAccessor> void pyramidExpandBurtFilter(triple<SrcIterator, SrcIterator, SrcAccessor> src, triple<DestIterator, DestIterator, DestAccessor> dest, double centerValue = 0.4); }
use a vigra::ImagePyramid :
namespace vigra { template <class Image, class Alloc> void pyramidExpandBurtFilter(ImagePyramid<Image, Alloc> & pyramid, int fromLevel, int toLevel, double centerValue = 0.4); }
void vigra::pyramidReduceBurtLaplacian | ( | ImagePyramid< Image, Alloc > & | pyramid, | |
int | fromLevel, | |||
int | toLevel, | |||
double | centerValue = 0.4 | |||
) |
Create a Laplacian pyramid.
Sorry, no detailedDocumentation() available yet.
#include <vigra/resampling_convolution.hxx>
Namespace: vigra
void vigra::pyramidExpandBurtLaplacian | ( | ImagePyramid< Image, Alloc > & | pyramid, | |
int | fromLevel, | |||
int | toLevel, | |||
double | centerValue = 0.4 | |||
) |
Reconstruct a Laplacian pyramid.
Sorry, no detailedDocumentation() available yet.
#include <vigra/resampling_convolution.hxx>
Namespace: vigra
© Ullrich Köthe (ullrich.koethe@iwr.uni-heidelberg.de) |
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