HALCON Operator reference

HALCON Operator Reference / Filters / FFT
ClassesClasses | | Operators

gen_gauss_filtergen_gauss_filterGenGaussFilterGenGaussFiltergen_gauss_filter (Operator)

gen_gauss_filtergen_gauss_filterGenGaussFilterGenGaussFiltergen_gauss_filter — 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)

def gen_gauss_filter(sigma_1: float, sigma_2: float, phi: float, norm: str, mode: str, width: int, height: int) -> HObject

Description

gen_gauss_filtergen_gauss_filterGenGaussFilterGenGaussFiltergen_gauss_filter 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 Sigma1Sigma1Sigma1sigma1sigma_1 and Sigma2Sigma2Sigma2sigma2sigma_2. Sigma1Sigma1Sigma1sigma1sigma_1 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_genericFftGenericFftGenericfft_generic 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_genericFftGenericFftGenericfft_generic is used, 'dc_edge'"dc_edge""dc_edge""dc_edge""dc_edge" can be used to gain efficiency. If fft_imagefft_imageFftImageFftImagefft_image and fft_image_invfft_image_invFftImageInvFftImageInvfft_image_inv 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_genericRftGenericRftGenericrft_generic is used, ModeModeModemodemode = 'rft'"rft""rft""rft""rft" must be used.

Execution Information

  • Multithreading type: reentrant (runs in parallel with non-exclusive operators).
  • Multithreading scope: global (may be called from any thread).
  • Processed without parallelization.

Parameters

ImageGaussImageGaussImageGaussimageGaussimage_gauss (output_object)  image → objectHImageHObjectHObjectHobject * (real)

Gaussian filter as image in the frequency domain.

Sigma1Sigma1Sigma1sigma1sigma_1 (input_control)  real → HTuplefloatHTupleHtuple (real) (double) (double) (double)

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

Default: 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

Sigma2Sigma2Sigma2sigma2sigma_2 (input_control)  real → HTuplefloatHTupleHtuple (real) (double) (double) (double)

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

Default: 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 → HTuplefloatHTupleHtuple (real) (double) (double) (double)

Principal direction of the filter in the spatial domain.

Default: 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 → HTuplestrHTupleHtuple (string) (string) (HString) (char*)

Normalizing factor of the filter.

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

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

ModeModeModemodemode (input_control)  string → HTuplestrHTupleHtuple (string) (string) (HString) (char*)

Location of the DC term in the frequency domain.

Default: '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 → HTupleintHTupleHtuple (integer) (int / long) (Hlong) (Hlong)

Width of the image (filter).

Default: 512

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

HeightHeightHeightheightheight (input_control)  integer → HTupleintHTupleHtuple (integer) (int / long) (Hlong) (Hlong)

Height of the image (filter).

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

Possible Predecessors

fft_imagefft_imageFftImageFftImagefft_image, fft_genericfft_genericFftGenericFftGenericfft_generic, rft_genericrft_genericRftGenericRftGenericrft_generic

Possible Successors

convol_fftconvol_fftConvolFftConvolFftconvol_fft

See also

fft_image_invfft_image_invFftImageInvFftImageInvfft_image_inv, gen_mean_filtergen_mean_filterGenMeanFilterGenMeanFiltergen_mean_filter, gen_derivative_filtergen_derivative_filterGenDerivativeFilterGenDerivativeFiltergen_derivative_filter, gen_lowpassgen_lowpassGenLowpassGenLowpassgen_lowpass, gen_bandpassgen_bandpassGenBandpassGenBandpassgen_bandpass, gen_bandfiltergen_bandfilterGenBandfilterGenBandfiltergen_bandfilter, gen_highpassgen_highpassGenHighpassGenHighpassgen_highpass

Module

Foundation

ClassesClasses | | Operators