gen_std_bandpass ( : ImageFilter : Frequency, Sigma, Size, Mode : )

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. For Mode = 'gauss', a Gaussian response is generated with Sigma being the standard deviation. For Mode = 'sin', a sine function is generated with the maximum at Frequency and the extent Sigma.


Parameters

ImageFilter (output_object)
image(-array) -> object : byte
Bandpass filter as image in the frequency domain.

Frequency (input_control)
real -> real
Distance of the filter's maximum from the DC term.
Default value: 20
Suggested values: 0.0, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 80, 100, 150, 200
Range of values: 0.0 <= Frequency <= 1000
Minimum increment: 1
Recommended increment: 2

Sigma (input_control)
real -> real
Bandwidth of the filter (standard deviation).
Default value: 1.0
Suggested values: 0.1, 0.3, 0.7, 1.0, 1.5, 2.0, 3.0, 5.0, 7.0, 10.0, 15.0, 20.0, 30.0, 50.0
Range of values: 0.05 <= Sigma <= 100.0
Minimum increment: 0.001
Recommended increment: 0.1

Size (input_control)
integer -> integer
Size (dimension) of the image (filter).
Default value: 512
List of values: 8, 16, 32, 64, 128, 256, 512, 1024, 2048, 4096, 8192

Mode (input_control)
string -> string
Filter type.
Default value: 'sin'
List of values: 'sin', 'gauss'


Result

gen_std_bandpass returns TRUE if all parameters are correct. If necessary, an exception is raised.


Possible Predecessors

fft__, fft_generic


Possible Successors

convol_fft__


Alternatives

gen_sin_bandpass, gen_bandpass, gen_bandfilter, gen_highpass, gen_lowpass


See also

fft_inv__



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