| Operators |
gen_bandpass — Generate an ideal bandpass filter.
gen_bandpass( : ImageBandpass : MinFrequency, MaxFrequency, Norm, Mode, Width, Height : )
gen_bandpass generates an ideal bandpass filter in the frequency domain. The parameters MinFrequency and MaxFrequency 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 Width x Height, i.e., MinFrequency and MaxFrequency should lie between 0 and 1. To achieve a maximum overall efficiency of the filtering operation, the parameter Norm can be used to specify the normalization factor of the filter. If fft_generic and Norm = 'n' is used the normalization in the FFT can be avoided. Mode 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_generic is used, 'dc_edge' can be used to gain efficiency. If fft_image and fft_image_inv are used for filtering, Norm = 'none' and Mode = 'dc_center' must be used. If rft_generic is used, Mode = 'rft' must be used. The resulting image contains an annulus with the value 255, and the value 0 outside of this annulus.
Bandpass filter in the frequency domain.
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
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
Normalizing factor of the filter.
Default value: 'none'
List of values: 'n', 'none'
Location of the DC term in the frequency domain.
Default value: 'dc_center'
List of values: 'dc_center', 'dc_edge', 'rft'
Width of the image (filter).
Default value: 512
Suggested values: 128, 160, 192, 256, 320, 384, 512, 640, 768, 1024, 2048, 4096, 8192
Height of the image (filter).
Default value: 512
Suggested values: 120, 128, 144, 240, 256, 288, 480, 512, 576, 1024, 2048, 4096, 8192
* 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')
gen_bandpass returns 2 (H_MSG_TRUE) if all parameters are correct. If necessary, an exception is raised.
gen_highpass, gen_lowpass, gen_bandfilter, gen_gauss_filter, gen_mean_filter, gen_derivative_filter
Foundation
| Operators |