gen_gauss_filtergen_gauss_filterGenGaussFilterGenGaussFilter (Operator)

Name

gen_gauss_filtergen_gauss_filterGenGaussFilterGenGaussFilter — Generate a Gaussian filter in the frequency domain.

Signature

gen_gauss_filter( : ImageGauss : Sigma1, Sigma2, Phi, Norm, Mode, Width, Height : )

Herror gen_gauss_filter(Hobject* ImageGauss, double Sigma1, double Sigma2, double Phi, const char* Norm, const char* Mode, const Hlong Width, const Hlong Height)

Herror T_gen_gauss_filter(Hobject* ImageGauss, const Htuple Sigma1, const Htuple Sigma2, const Htuple Phi, const Htuple Norm, const Htuple Mode, const Htuple Width, const Htuple Height)

void GenGaussFilter(HObject* ImageGauss, const HTuple& Sigma1, const HTuple& Sigma2, const HTuple& Phi, const HTuple& Norm, const HTuple& Mode, const HTuple& Width, const HTuple& Height)

void HImage::GenGaussFilter(double Sigma1, double Sigma2, double Phi, const HString& Norm, const HString& Mode, Hlong Width, Hlong Height)

void HImage::GenGaussFilter(double Sigma1, double Sigma2, double Phi, const char* Norm, const char* Mode, Hlong Width, Hlong Height)

void HImage::GenGaussFilter(double Sigma1, double Sigma2, double Phi, const wchar_t* Norm, const wchar_t* Mode, Hlong Width, Hlong Height)   (Windows only)

static void HOperatorSet.GenGaussFilter(out HObject imageGauss, HTuple sigma1, HTuple sigma2, HTuple phi, HTuple norm, HTuple mode, HTuple width, HTuple height)

void HImage.GenGaussFilter(double sigma1, double sigma2, double phi, string norm, string mode, int width, int height)

Description

gen_gauss_filtergen_gauss_filterGenGaussFilterGenGaussFilterGenGaussFilter generates a (possibly anisotropic) Gaussian filter in the frequency domain. The standard deviations (i.e., the amount of smoothing) of the Gaussian in the spatial domain are determined by Sigma1Sigma1Sigma1Sigma1sigma1 and Sigma2Sigma2Sigma2Sigma2sigma2. Sigma1Sigma1Sigma1Sigma1sigma1 is the standard deviation in the principal direction of the filter in the spatial domain determined by the angle PhiPhiPhiPhiphi. To achieve a maximum overall efficiency of the filtering operation, the parameter NormNormNormNormnorm can be used to specify the normalization factor of the filter. If fft_genericfft_genericFftGenericFftGenericFftGeneric and NormNormNormNormnorm = 'n'"n""n""n""n" is used the normalization in the FFT can be avoided. ModeModeModeModemode can be used to determine where the DC term of the filter lies or whether the filter should be used in the real-valued FFT. If fft_genericfft_genericFftGenericFftGenericFftGeneric is used, 'dc_edge'"dc_edge""dc_edge""dc_edge""dc_edge" can be used to gain efficiency. If fft_imagefft_imageFftImageFftImageFftImage and fft_image_invfft_image_invFftImageInvFftImageInvFftImageInv are used for filtering, NormNormNormNormnorm = 'none'"none""none""none""none" and ModeModeModeModemode = 'dc_center'"dc_center""dc_center""dc_center""dc_center" must be used. If rft_genericrft_genericRftGenericRftGenericRftGeneric is used, ModeModeModeModemode = 'rft'"rft""rft""rft""rft" must be used.

Execution Information

Parameters

ImageGaussImageGaussImageGaussImageGaussimageGauss (output_object)  image objectHImageHImageHobject * (real)

Gaussian filter as image in the frequency domain.

Sigma1Sigma1Sigma1Sigma1sigma1 (input_control)  real HTupleHTupleHtuple (real) (double) (double) (double)

Standard deviation of the Gaussian in the principal direction of the filter in the spatial domain.

Default value: 1.0

Suggested values: 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.5, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, 10.0

Restriction: Sigma1 >= 0

Sigma2Sigma2Sigma2Sigma2sigma2 (input_control)  real HTupleHTupleHtuple (real) (double) (double) (double)

Standard deviation of the Gaussian perpendicular to the principal direction of the filter in the spatial domain.

Default value: 1.0

Suggested values: 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.5, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, 10.0

Restriction: Sigma2 >= 0

PhiPhiPhiPhiphi (input_control)  angle.rad HTupleHTupleHtuple (real) (double) (double) (double)

Principal direction of the filter in the spatial domain.

Default value: 0.0

Suggested values: 0.0, 0.523599, 0.785398, 1.047198, 1.570796, 2.094395, 2.356194, 2.617994, 3.141593

NormNormNormNormnorm (input_control)  string HTupleHTupleHtuple (string) (string) (HString) (char*)

Normalizing factor of the filter.

Default value: 'none' "none" "none" "none" "none"

List of values: 'n'"n""n""n""n", 'none'"none""none""none""none"

ModeModeModeModemode (input_control)  string HTupleHTupleHtuple (string) (string) (HString) (char*)

Location of the DC term in the frequency domain.

Default value: 'dc_center' "dc_center" "dc_center" "dc_center" "dc_center"

List of values: 'dc_center'"dc_center""dc_center""dc_center""dc_center", 'dc_edge'"dc_edge""dc_edge""dc_edge""dc_edge", 'rft'"rft""rft""rft""rft"

WidthWidthWidthWidthwidth (input_control)  integer HTupleHTupleHtuple (integer) (int / long) (Hlong) (Hlong)

Width of the image (filter).

Default value: 512

Suggested values: 128, 160, 192, 256, 320, 384, 512, 640, 768, 1024, 2048, 4096, 8192

HeightHeightHeightHeightheight (input_control)  integer HTupleHTupleHtuple (integer) (int / long) (Hlong) (Hlong)

Height of the image (filter).

Default value: 512

Suggested values: 120, 128, 144, 240, 256, 288, 480, 512, 576, 1024, 2048, 4096, 8192

Example (HDevelop)

* Generate a smoothed derivative filter.
gen_gauss_filter (ImageGauss, Sigma, Sigma, 0, 'n', 'dc_edge', 512, 512)
convert_image_type (ImageGauss, ImageGaussComplex, 'complex')
gen_derivative_filter (ImageDerivX, 'x', 1, 'none', 'dc_edge', 512, 512)
mult_image (ImageGaussComplex, ImageDerivX, ImageDerivXGauss, 1, 0)
* Filter an image with the smoothed derivative filter.
fft_generic (Image, ImageFFT, 'to_freq', -1, 'none', 'dc_edge', 'complex')
convol_fft (ImageFFT, ImageDerivXGauss, Filtered)
fft_generic (Filtered, ImageX, 'from_freq', 1, 'none', 'dc_edge', 'real')

Result

gen_gauss_filtergen_gauss_filterGenGaussFilterGenGaussFilterGenGaussFilter returns 2 (H_MSG_TRUE) if all parameters are correct. If necessary, an exception is raised.

Possible Predecessors

fft_imagefft_imageFftImageFftImageFftImage, fft_genericfft_genericFftGenericFftGenericFftGeneric, rft_genericrft_genericRftGenericRftGenericRftGeneric

Possible Successors

convol_fftconvol_fftConvolFftConvolFftConvolFft

See also

fft_image_invfft_image_invFftImageInvFftImageInvFftImageInv, gen_mean_filtergen_mean_filterGenMeanFilterGenMeanFilterGenMeanFilter, gen_derivative_filtergen_derivative_filterGenDerivativeFilterGenDerivativeFilterGenDerivativeFilter, gen_lowpassgen_lowpassGenLowpassGenLowpassGenLowpass, gen_bandpassgen_bandpassGenBandpassGenBandpassGenBandpass, gen_bandfiltergen_bandfilterGenBandfilterGenBandfilterGenBandfilter, gen_highpassgen_highpassGenHighpassGenHighpassGenHighpass

Module

Foundation