gen_highpassgen_highpassGenHighpassGenHighpassgen_highpass (Operator)

Name

gen_highpassgen_highpassGenHighpassGenHighpassgen_highpass — Generate an ideal highpass filter.

Signature

gen_highpass( : ImageHighpass : Frequency, Norm, Mode, Width, Height : )

Herror gen_highpass(Hobject* ImageHighpass, double Frequency, const char* Norm, const char* Mode, const Hlong Width, const Hlong Height)

Herror T_gen_highpass(Hobject* ImageHighpass, const Htuple Frequency, const Htuple Norm, const Htuple Mode, const Htuple Width, const Htuple Height)

void GenHighpass(HObject* ImageHighpass, const HTuple& Frequency, const HTuple& Norm, const HTuple& Mode, const HTuple& Width, const HTuple& Height)

void HImage::GenHighpass(double Frequency, const HString& Norm, const HString& Mode, Hlong Width, Hlong Height)

void HImage::GenHighpass(double Frequency, const char* Norm, const char* Mode, Hlong Width, Hlong Height)

void HImage::GenHighpass(double Frequency, const wchar_t* Norm, const wchar_t* Mode, Hlong Width, Hlong Height)   (Windows only)

static void HOperatorSet.GenHighpass(out HObject imageHighpass, HTuple frequency, HTuple norm, HTuple mode, HTuple width, HTuple height)

void HImage.GenHighpass(double frequency, string norm, string mode, int width, int height)

def gen_highpass(frequency: float, norm: str, mode: str, width: int, height: int) -> HObject

Description

gen_highpassgen_highpassGenHighpassGenHighpassGenHighpassgen_highpass generates an ideal highpass filter in the frequency domain. The parameter FrequencyFrequencyFrequencyFrequencyfrequencyfrequency determines the cutoff frequency of the filter as a fraction of the maximum (horizontal and vertical) frequency that can be represented in an image of size WidthWidthWidthWidthwidthwidth x HeightHeightHeightHeightheightheight, i.e., FrequencyFrequencyFrequencyFrequencyfrequencyfrequency should lie between 0 and 1. To achieve a maximum overall efficiency of the filtering operation, the parameter NormNormNormNormnormnorm can be used to specify the normalization factor of the filter. If fft_genericfft_genericFftGenericFftGenericFftGenericfft_generic and NormNormNormNormnormnorm = 'n'"n""n""n""n""n" is used the normalization in the FFT can be avoided. ModeModeModeModemodemode 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_genericFftGenericFftGenericFftGenericfft_generic is used, 'dc_edge'"dc_edge""dc_edge""dc_edge""dc_edge""dc_edge" can be used to gain efficiency. If fft_imagefft_imageFftImageFftImageFftImagefft_image and fft_image_invfft_image_invFftImageInvFftImageInvFftImageInvfft_image_inv are used for filtering, NormNormNormNormnormnorm = 'none'"none""none""none""none""none" and ModeModeModeModemodemode = 'dc_center'"dc_center""dc_center""dc_center""dc_center""dc_center" must be used. If rft_genericrft_genericRftGenericRftGenericRftGenericrft_generic is used, ModeModeModeModemodemode = 'rft'"rft""rft""rft""rft""rft" must be used. The resulting image has an inner part with the value 0, and an outer part with the value determined by the normalization factor.

Execution Information

Parameters

ImageHighpassImageHighpassImageHighpassImageHighpassimageHighpassimage_highpass (output_object)  image objectHImageHObjectHImageHobject * (real)

Highpass filter in the frequency domain.

FrequencyFrequencyFrequencyFrequencyfrequencyfrequency (input_control)  real HTuplefloatHTupleHtuple (real) (double) (double) (double)

Cutoff frequency.

Default value: 0.1

Suggested values: 0.0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0

Restriction: Frequency >= 0

NormNormNormNormnormnorm (input_control)  string HTuplestrHTupleHtuple (string) (string) (HString) (char*)

Normalizing factor of the filter.

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

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

ModeModeModeModemodemode (input_control)  string HTuplestrHTupleHtuple (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" "dc_center"

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

WidthWidthWidthWidthwidthwidth (input_control)  integer HTupleintHTupleHtuple (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

HeightHeightHeightHeightheightheight (input_control)  integer HTupleintHTupleHtuple (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)

* Filtering with maximum efficiency with fft_generic.
gen_highpass(Highpass,0.2,'n','dc_edge',Width,Height)
fft_generic(Image,ImageFFT,'to_freq',-1,'none','dc_edge','complex')
convol_fft(ImageFFT,Highpass,ImageConvol)
fft_generic(ImageConvol,ImageResult,'from_freq',1,'none','dc_edge','byte')

Result

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

Possible Successors

convol_fftconvol_fftConvolFftConvolFftConvolFftconvol_fft

See also

convol_fftconvol_fftConvolFftConvolFftConvolFftconvol_fft, gen_lowpassgen_lowpassGenLowpassGenLowpassGenLowpassgen_lowpass, gen_bandpassgen_bandpassGenBandpassGenBandpassGenBandpassgen_bandpass, gen_bandfiltergen_bandfilterGenBandfilterGenBandfilterGenBandfiltergen_bandfilter, gen_gauss_filtergen_gauss_filterGenGaussFilterGenGaussFilterGenGaussFiltergen_gauss_filter, gen_mean_filtergen_mean_filterGenMeanFilterGenMeanFilterGenMeanFiltergen_mean_filter, gen_derivative_filtergen_derivative_filterGenDerivativeFilterGenDerivativeFilterGenDerivativeFiltergen_derivative_filter

Module

Foundation