gen_sin_bandpass ( : ImageFilter : Frequency, Size : )

Generate a bandpass filter with sinusoidal shape.

gen_sin_bandpass generates a rotationally invariant bandpass filter with the response being a sinusoidal function in the frequency domain. The maximum of the sine (255) is determined by Frequency (distance from the DC term in pixels). The filter is always zero for the DC term, rises with the sine function up to Frequency, and drops for higher frequencies accordingly. The range of the sine used is from 0 to pi. All other points are set to zero.


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

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


Result

gen_sin_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_std_bandpass, gen_bandpass, gen_bandfilter, gen_highpass, gen_lowpass


See also

fft_inv__



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