gen_sin_bandpassgen_sin_bandpassGenSinBandpassGenSinBandpass (Operator)

Name

gen_sin_bandpassgen_sin_bandpassGenSinBandpassGenSinBandpass — Generate a bandpass filter with sinusoidal shape.

Signature

gen_sin_bandpass( : ImageFilter : Frequency, Norm, Mode, Width, Height : )

gen_sin_bandpassgen_sin_bandpassGenSinBandpassGenSinBandpassGenSinBandpass generates a rotationally invariant bandpass filter with the response being a sinusoidal function in the frequency domain. The maximum of the sine is determined by FrequencyFrequencyFrequencyFrequencyfrequency, which is given as a fraction of the maximum (horizontal and vertical) frequency that can be represented in an image of size WidthWidthWidthWidthwidth x HeightHeightHeightHeightheight, i.e., FrequencyFrequencyFrequencyFrequencyfrequency should lie between 0 and 1. To achieve a maximum overall efficiency of the filtering operation, the parameter NormNormNormNormnorm can be used to specify the normalization factor of the filter. If fft_genericfft_genericFftGenericFftGenericFftGeneric and NormNormNormNormnorm = 'n'"n""n""n""n" is used the normalization in the FFT can be avoided. ModeModeModeModemode 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_genericFftGenericFftGenericFftGeneric is used, 'dc_edge'"dc_edge""dc_edge""dc_edge""dc_edge" can be used to gain efficiency. If fft_imagefft_imageFftImageFftImageFftImage and fft_image_invfft_image_invFftImageInvFftImageInvFftImageInv are used for filtering, NormNormNormNormnorm = 'none'"none""none""none""none" and ModeModeModeModemode = 'dc_center'"dc_center""dc_center""dc_center""dc_center" must be used. If rft_genericrft_genericRftGenericRftGenericRftGeneric is used, ModeModeModeModemode = 'rft'"rft""rft""rft""rft" must be used. The filter is always zero for the DC term, rises with the sine function up to FrequencyFrequencyFrequencyFrequencyfrequency, and drops for higher frequencies accordingly. The range of the sine used is from 0 to . All other points are set to zero.

Execution Information

Multithreading type: reentrant (runs in parallel with non-exclusive operators).
Multithreading scope: global (may be called from any thread).
Processed without parallelization.

Parameters

ImageFilterImageFilterImageFilterImageFilterimageFilter (output_object) image → object (real)

Bandpass filter as image in the frequency domain.

FrequencyFrequencyFrequencyFrequencyfrequency (input_control) real → (real)

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

NormNormNormNormnorm (input_control) string → (string)

Normalizing factor of the filter.

Default value: 'none' "none" "none" "none" "none"

List of values: 'n'"n""n""n""n", 'none'"none""none""none""none"

ModeModeModeModemode (input_control) string → (string)

Location of the DC term in the frequency domain.

Default value: 'dc_center' "dc_center" "dc_center" "dc_center" "dc_center"

List of values: 'dc_center'"dc_center""dc_center""dc_center""dc_center", 'dc_edge'"dc_edge""dc_edge""dc_edge""dc_edge", 'rft'"rft""rft""rft""rft"

WidthWidthWidthWidthwidth (input_control) integer → (integer)

Width of the image (filter).

Default value: 512

Suggested values: 128, 160, 192, 256, 320, 384, 512, 640, 768, 1024, 2048, 4096, 8192

HeightHeightHeightHeightheight (input_control) integer → (integer)

Height of the image (filter).

Default value: 512

Suggested values: 120, 128, 144, 240, 256, 288, 480, 512, 576, 1024, 2048, 4096, 8192

Result

gen_sin_bandpassgen_sin_bandpassGenSinBandpassGenSinBandpassGenSinBandpass returns 2 (H_MSG_TRUE) if all parameters are correct. If necessary, an exception is raised.