gen_lowpassGenLowpassGenLowpassgen_lowpassgen_lowpass

HALCON ScriptCpp++.NETPythonC

Short description

gen_lowpassGenLowpassGenLowpassgen_lowpassgen_lowpass — Generate an ideal lowpass filter.

Signature

gen_lowpass( out image ImageLowpass, real Frequency, string Norm, string Mode, integer Width, integer Height )void GenLowpass( HObject* ImageLowpass, const HTuple& Frequency, const HTuple& Norm, const HTuple& Mode, const HTuple& Width, const HTuple& Height )static void HOperatorSet.GenLowpass( out HObject imageLowpass, HTuple frequency, HTuple norm, HTuple mode, HTuple width, HTuple height )def gen_lowpass( frequency: float, norm: str, mode: str, width: int, height: int ) -> HObject

Herror gen_lowpass( Hobject* ImageLowpass, double Frequency, const char* Norm, const char* Mode, const Hlong Width, const Hlong Height )

Herror T_gen_lowpass( Hobject* ImageLowpass, const Htuple Frequency, const Htuple Norm, const Htuple Mode, const Htuple Width, const Htuple Height )

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

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

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

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

Description

gen_lowpassGenLowpass generates an ideal lowpass filter in the frequency domain. The parameter Frequencyfrequencyfrequency 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 Widthwidthwidth x Heightheightheight, i.e., Frequencyfrequencyfrequency should lie between 0 and 1. To achieve a maximum overall efficiency of the filtering operation, the parameter Normnormnorm can be used to specify the normalization factor of the filter. If fft_genericFftGeneric and Normnormnorm \(=\) 'n'"n" is used the normalization in the FFT can be avoided. Modemodemode 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_genericFftGeneric is used, 'dc_edge'"dc_edge" can be used to gain efficiency. If fft_imageFftImage and fft_image_invFftImageInv are used for filtering, Normnormnorm \(=\) 'none'"none" and Modemodemode \(=\) 'dc_center'"dc_center" must be used. If rft_genericRftGeneric is used, Modemodemode \(=\) 'rft'"rft" must be used. The resulting image has an inner part with the value set to the normalization factor, and an outer part with the value 0.

Execution information

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

ImageLowpassimageLowpassimage_lowpass (output_object) image → object (real)HObject (real)HImage (real)HObject (real)Hobject * (real)

Lowpass filter in the frequency domain.

Frequencyfrequencyfrequency (input_control) real → (real)HTuple (double)HTuple (double)floatHtuple (double)

Cutoff frequency.

Default: 0.10.1
Suggested values: 0.0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.00.0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0
Restriction: Frequency >= 0

Normnormnorm (input_control) string → (string)HTuple (HString)HTuple (string)strHtuple (char*)

Normalizing factor of the filter.

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

Modemodemode (input_control) string → (string)HTuple (HString)HTuple (string)strHtuple (char*)

Location of the DC term in the frequency domain.

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

Widthwidthwidth (input_control) integer → (integer)HTuple (Hlong)HTuple (int / long)intHtuple (Hlong)

Width of the image (filter).

Default: 512512
Suggested values: 128, 160, 192, 256, 320, 384, 512, 640, 768, 1024, 2048, 4096, 8192128, 160, 192, 256, 320, 384, 512, 640, 768, 1024, 2048, 4096, 8192

Heightheightheight (input_control) integer → (integer)HTuple (Hlong)HTuple (int / long)intHtuple (Hlong)

Height of the image (filter).

Default: 512512
Suggested values: 120, 128, 144, 240, 256, 288, 480, 512, 576, 1024, 2048, 4096, 8192120, 128, 144, 240, 256, 288, 480, 512, 576, 1024, 2048, 4096, 8192

Example

(HDevelop)

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

Result

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

Combinations with other operators

Combinations

Possible successors

convol_fftConvolFft

See also

gen_highpassGenHighpass, gen_bandpassGenBandpass, gen_bandfilterGenBandfilter, gen_gauss_filterGenGaussFilter, gen_mean_filterGenMeanFilter, gen_derivative_filterGenDerivativeFilter

Module

Foundation