gen_bandpassgen_bandpassGenBandpassGenBandpass (Operator)
Name
gen_bandpassgen_bandpassGenBandpassGenBandpass — Generate an ideal bandpass filter.
Signature
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)
Description
gen_bandpassgen_bandpassGenBandpassGenBandpassGenBandpass generates an ideal bandpass filter in the
frequency domain. The parameters MinFrequencyMinFrequencyMinFrequencyMinFrequencyminFrequency and
MaxFrequencyMaxFrequencyMaxFrequencyMaxFrequencymaxFrequency 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 WidthWidthWidthWidthwidth
x HeightHeightHeightHeightheight, i.e., MinFrequencyMinFrequencyMinFrequencyMinFrequencyminFrequency and
MaxFrequencyMaxFrequencyMaxFrequencyMaxFrequencymaxFrequency should lie between 0 and 1. 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. The resulting
image contains an annulus with the value 255, and the value 0
outside of this annulus.
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
ImageBandpassImageBandpassImageBandpassImageBandpassimageBandpass (output_object) image → objectHImageHImageHobject * (real)
Bandpass filter in the frequency domain.
MinFrequencyMinFrequencyMinFrequencyMinFrequencyminFrequency (input_control) real → HTupleHTupleHtuple (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
MaxFrequencyMaxFrequencyMaxFrequencyMaxFrequencymaxFrequency (input_control) real → HTupleHTupleHtuple (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
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)
* 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_bandpassGenBandpassGenBandpassGenBandpass returns 2 (H_MSG_TRUE) if all parameters are correct.
If necessary, an exception is raised.
Possible Successors
convol_fftconvol_fftConvolFftConvolFftConvolFft
See also
gen_highpassgen_highpassGenHighpassGenHighpassGenHighpass,
gen_lowpassgen_lowpassGenLowpassGenLowpassGenLowpass,
gen_bandfiltergen_bandfilterGenBandfilterGenBandfilterGenBandfilter,
gen_gauss_filtergen_gauss_filterGenGaussFilterGenGaussFilterGenGaussFilter,
gen_mean_filtergen_mean_filterGenMeanFilterGenMeanFilterGenMeanFilter,
gen_derivative_filtergen_derivative_filterGenDerivativeFilterGenDerivativeFilterGenDerivativeFilter
Module
Foundation