gen_std_bandpass — Generate a bandpass filter with Gaussian or sinusoidal shape.
gen_std_bandpass generates a rotationally invariant bandpass filter with the response being determined by the parameters Frequency and Sigma: Frequency determines the location of the maximum response with respect to the DC term, while Sigma determines the width of the frequency band that passes the filter. Frequency and Sigma are specified as a fraction of the maximum (horizontal and vertical) frequency that can be represented in an image of size Width x Height. Frequency should lie between 0 and 1. For Type = 'gauss', a Gaussian response is generated with Sigma being the standard deviation. For Type = 'sin', a sine function is generated with the maximum at Frequency and the extent Sigma. 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.
Bandpass filter as image in the frequency domain.
Distance of the filter's maximum from the DC term.
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: Frequency >= 0
Bandwidth of the filter (standard deviation).
Default value: 0.01
Suggested values: 0.002, 0.005, 0.01, 0.02, 0.05, 0.1, 0.2, 0.3, 0.4, 0.5, 0.7, 1.0
Restriction: Sigma >= 0
Default value: 'sin'
List of values: 'gauss', 'sin'
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
gen_std_bandpass returns 2 (H_MSG_TRUE) if all parameters are correct. If necessary, an exception is raised.
fft_image, fft_generic, rft_generic
fft_image_inv, gen_gauss_filter, gen_mean_filter, gen_derivative_filter, gen_bandpass, gen_bandfilter, gen_highpass, gen_lowpass