gen_bandpassgen_bandpassGenBandpassGenBandpassgen_bandpass (Operator)

Name

gen_bandpassgen_bandpassGenBandpassGenBandpassgen_bandpass — Generate an ideal bandpass filter.

Signature

gen_bandpass( : ImageBandpass : MinFrequency, MaxFrequency, Norm, Mode, Width, Height : )

Herror gen_bandpass(Hobject* ImageBandpass, double MinFrequency, double MaxFrequency, const char* Norm, const char* Mode, const Hlong Width, const Hlong Height)

Herror T_gen_bandpass(Hobject* ImageBandpass, const Htuple MinFrequency, const Htuple MaxFrequency, const Htuple Norm, const Htuple Mode, const Htuple Width, const Htuple Height)

void GenBandpass(HObject* ImageBandpass, const HTuple& MinFrequency, const HTuple& MaxFrequency, const HTuple& Norm, const HTuple& Mode, const HTuple& Width, const HTuple& Height)

void HImage::GenBandpass(double MinFrequency, double MaxFrequency, const HString& Norm, const HString& Mode, Hlong Width, Hlong Height)

void HImage::GenBandpass(double MinFrequency, double MaxFrequency, const char* Norm, const char* Mode, Hlong Width, Hlong Height)

void HImage::GenBandpass(double MinFrequency, double MaxFrequency, const wchar_t* Norm, const wchar_t* Mode, Hlong Width, Hlong Height)   (Windows only)

static void HOperatorSet.GenBandpass(out HObject imageBandpass, HTuple minFrequency, HTuple maxFrequency, HTuple norm, HTuple mode, HTuple width, HTuple height)

void HImage.GenBandpass(double minFrequency, double maxFrequency, string norm, string mode, int width, int height)

def gen_bandpass(min_frequency: float, max_frequency: float, norm: str, mode: str, width: int, height: int) -> HObject

Description

gen_bandpassgen_bandpassGenBandpassGenBandpassGenBandpassgen_bandpass generates an ideal bandpass filter in the frequency domain. The parameters MinFrequencyMinFrequencyMinFrequencyMinFrequencyminFrequencymin_frequency and MaxFrequencyMaxFrequencyMaxFrequencyMaxFrequencymaxFrequencymax_frequency determine the cutoff frequencies 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., MinFrequencyMinFrequencyMinFrequencyMinFrequencyminFrequencymin_frequency and MaxFrequencyMaxFrequencyMaxFrequencyMaxFrequencymaxFrequencymax_frequency 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 contains an annulus with the value 255, and the value 0 outside of this annulus.

Execution Information

Parameters

ImageBandpassImageBandpassImageBandpassImageBandpassimageBandpassimage_bandpass (output_object)  image objectHImageHObjectHImageHobject * (real)

Bandpass filter in the frequency domain.

MinFrequencyMinFrequencyMinFrequencyMinFrequencyminFrequencymin_frequency (input_control)  real HTuplefloatHTupleHtuple (real) (double) (double) (double)

Minimum 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: MinFrequency >= 0

MaxFrequencyMaxFrequencyMaxFrequencyMaxFrequencymaxFrequencymax_frequency (input_control)  real HTuplefloatHTupleHtuple (real) (double) (double) (double)

Maximum frequency.

Default value: 0.2

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: MaxFrequency >= 0 && MaxFrequency >= MinFrequency

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_bandpass(Bandpass,0.2,0.4,'n','dc_edge',Width,Height)
fft_generic(Image,ImageFFT,'to_freq',-1,'none','dc_edge','complex')
convol_fft(ImageFFT,Bandpass,ImageConvol)
fft_generic(ImageConvol,ImageResult,'from_freq',1,'none','dc_edge','byte')

Result

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

Possible Successors

convol_fftconvol_fftConvolFftConvolFftConvolFftconvol_fft

See also

gen_highpassgen_highpassGenHighpassGenHighpassGenHighpassgen_highpass, gen_lowpassgen_lowpassGenLowpassGenLowpassGenLowpassgen_lowpass, 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