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gen_bandfiltergen_bandfilterGenBandfiltergen_bandfilterGenBandfilterGenBandfilter (Operator)

Name

gen_bandfiltergen_bandfilterGenBandfiltergen_bandfilterGenBandfilterGenBandfilter — Generate an ideal band filter.

Signature

gen_bandfilter( : ImageFilter : MinFrequency, MaxFrequency, Norm, Mode, Width, Height : )

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

Herror T_gen_bandfilter(Hobject* ImageFilter, const Htuple MinFrequency, const Htuple MaxFrequency, const Htuple Norm, const Htuple Mode, const Htuple Width, const Htuple Height)

Herror gen_bandfilter(Hobject* ImageFilter, const HTuple& MinFrequency, const HTuple& MaxFrequency, const HTuple& Norm, const HTuple& Mode, const HTuple& Width, const HTuple& Height)

HImage HImage::GenBandfilter(const HTuple& MinFrequency, const HTuple& MaxFrequency, const HTuple& Norm, const HTuple& Mode, const HTuple& Width, const HTuple& Height)

void GenBandfilter(HObject* ImageFilter, const HTuple& MinFrequency, const HTuple& MaxFrequency, const HTuple& Norm, const HTuple& Mode, const HTuple& Width, const HTuple& Height)

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

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

void HOperatorSetX.GenBandfilter(
[out] IHUntypedObjectX** ImageFilter, [in] VARIANT MinFrequency, [in] VARIANT MaxFrequency, [in] VARIANT Norm, [in] VARIANT Mode, [in] VARIANT Width, [in] VARIANT Height)

void HImageX.GenBandfilter(
[in] double MinFrequency, [in] double MaxFrequency, [in] BSTR Norm, [in] BSTR Mode, [in] Hlong Width, [in] Hlong Height)

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

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

Description

gen_bandfiltergen_bandfilterGenBandfiltergen_bandfilterGenBandfilterGenBandfilter generates an ideal band filter in the frequency domain. The parameters MinFrequencyMinFrequencyMinFrequencyMinFrequencyMinFrequencyminFrequency and MaxFrequencyMaxFrequencyMaxFrequencyMaxFrequencyMaxFrequencymaxFrequency 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., MinFrequencyMinFrequencyMinFrequencyMinFrequencyMinFrequencyminFrequency and MaxFrequencyMaxFrequencyMaxFrequencyMaxFrequencyMaxFrequencymaxFrequency 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_genericFftGenericfft_genericFftGenericFftGeneric 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_genericFftGenericfft_genericFftGenericFftGeneric is used, 'dc_edge'"dc_edge""dc_edge""dc_edge""dc_edge""dc_edge" can be used to gain efficiency. If fft_imagefft_imageFftImagefft_imageFftImageFftImage and fft_image_invfft_image_invFftImageInvfft_image_invFftImageInvFftImageInv 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_genericRftGenericrft_genericRftGenericRftGeneric is used, ModeModeModeModeModemode = 'rft'"rft""rft""rft""rft""rft" must be used. The resulting image contains an annulus with the value 0, and a value determined by the normalization outside of this annulus.

Parallelization

Parameters

ImageFilterImageFilterImageFilterImageFilterImageFilterimageFilter (output_object)  image → objectHImageHImageHImageHImageXHobject * (real)

Band filter in the frequency domain.

MinFrequencyMinFrequencyMinFrequencyMinFrequencyMinFrequencyminFrequency (input_control)  real → HTupleHTupleHTupleVARIANTHtuple (real) (double) (double) (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

MaxFrequencyMaxFrequencyMaxFrequencyMaxFrequencyMaxFrequencymaxFrequency (input_control)  real → HTupleHTupleHTupleVARIANTHtuple (real) (double) (double) (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 → HTupleHTupleHTupleVARIANTHtuple (string) (string) (HString) (char*) (BSTR) (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 → HTupleHTupleHTupleVARIANTHtuple (string) (string) (HString) (char*) (BSTR) (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 → HTupleHTupleHTupleVARIANTHtuple (integer) (int / long) (Hlong) (Hlong) (Hlong) (Hlong)

Width of the image (filter).

Default value: 512

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

HeightHeightHeightHeightHeightheight (input_control)  integer → HTupleHTupleHTupleVARIANTHtuple (integer) (int / long) (Hlong) (Hlong) (Hlong) (Hlong)

Height of the image (filter).

Default value: 512

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

Result

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

Possible Successors

convol_fftconvol_fftConvolFftconvol_fftConvolFftConvolFft

Alternatives

gen_circlegen_circleGenCirclegen_circleGenCircleGenCircle, paint_regionpaint_regionPaintRegionpaint_regionPaintRegionPaintRegion

See also

gen_highpassgen_highpassGenHighpassgen_highpassGenHighpassGenHighpass, gen_lowpassgen_lowpassGenLowpassgen_lowpassGenLowpassGenLowpass, gen_bandpassgen_bandpassGenBandpassgen_bandpassGenBandpassGenBandpass, gen_gauss_filtergen_gauss_filterGenGaussFiltergen_gauss_filterGenGaussFilterGenGaussFilter, gen_mean_filtergen_mean_filterGenMeanFiltergen_mean_filterGenMeanFilterGenMeanFilter, gen_derivative_filtergen_derivative_filterGenDerivativeFiltergen_derivative_filterGenDerivativeFilterGenDerivativeFilter

Module

Foundation

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