gen_bandpassgen_bandpassGenBandpassGenBandpassgen_bandpass（算子）
名称
gen_bandpassgen_bandpassGenBandpassGenBandpassgen_bandpass — 生成理想的带通滤波器。
签名
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)
描述
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.
执行信息
- 多线程类型：可重入（与非独占算子并行运行）。
- 多线程作用域：全局（可从任何线程调用）。
- 未采用并行化处理。
参数
ImageBandpassImageBandpassImageBandpassImageBandpassimageBandpassimage_bandpass (输出对象) image → objectHImageHObjectHImageHobject * (real)
Bandpass filter in the frequency domain.
MinFrequencyMinFrequencyMinFrequencyMinFrequencyminFrequencymin_frequency (输入控制) real → HTuplefloatHTupleHtuple (real) (double) (double) (double)
Minimum frequency.
默认值：
0.1
建议值：
0.0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0
限制：
MinFrequency >= 0
MaxFrequencyMaxFrequencyMaxFrequencyMaxFrequencymaxFrequencymax_frequency (输入控制) real → HTuplefloatHTupleHtuple (real) (double) (double) (double)
Maximum frequency.
默认值：
0.2
建议值：
0.0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0
限制：
MaxFrequency >= 0 && MaxFrequency >= MinFrequency
NormNormNormNormnormnorm (输入控制) string → HTuplestrHTupleHtuple (string) (string) (HString) (char*)
Normalizing factor of the filter.
默认值：
'none'
"none"
"none"
"none"
"none"
"none"
值列表：
'n'"n""n""n""n""n", 'none'"none""none""none""none""none"
ModeModeModeModemodemode (输入控制) string → HTuplestrHTupleHtuple (string) (string) (HString) (char*)
Location of the DC term in the frequency domain.
默认值：
'dc_center'
"dc_center"
"dc_center"
"dc_center"
"dc_center"
"dc_center"
值列表：
'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 (输入控制) integer → HTupleintHTupleHtuple (integer) (int / long) (Hlong) (Hlong)
Width of the image (filter).
默认值：
512
建议值：
128, 160, 192, 256, 320, 384, 512, 640, 768, 1024, 2048, 4096, 8192
HeightHeightHeightHeightheightheight (输入控制) integer → HTupleintHTupleHtuple (integer) (int / long) (Hlong) (Hlong)
Height of the image (filter).
默认值：
512
建议值：
120, 128, 144, 240, 256, 288, 480, 512, 576, 1024, 2048, 4096, 8192
示例（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')
结果
gen_bandpassgen_bandpassGenBandpassGenBandpassGenBandpassgen_bandpass 在所有参数正确时返回 2 ( H_MSG_TRUE )。如有必要，则抛出异常。
可能的后继
convol_fftconvol_fftConvolFftConvolFftConvolFftconvol_fft
另见
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
模块
基础