gen_derivative_filtergen_derivative_filterGenDerivativeFilterGenDerivativeFiltergen_derivative_filter (Operator)

Name

gen_derivative_filtergen_derivative_filterGenDerivativeFilterGenDerivativeFiltergen_derivative_filter — Generate a derivative filter in the frequency domain.

Signature

gen_derivative_filter( : ImageDerivative : Derivative, Exponent, Norm, Mode, Width, Height : )

Herror gen_derivative_filter(Hobject* ImageDerivative, const char* Derivative, const Hlong Exponent, const char* Norm, const char* Mode, const Hlong Width, const Hlong Height)

Herror T_gen_derivative_filter(Hobject* ImageDerivative, const Htuple Derivative, const Htuple Exponent, const Htuple Norm, const Htuple Mode, const Htuple Width, const Htuple Height)

void GenDerivativeFilter(HObject* ImageDerivative, const HTuple& Derivative, const HTuple& Exponent, const HTuple& Norm, const HTuple& Mode, const HTuple& Width, const HTuple& Height)

void HImage::GenDerivativeFilter(const HString& Derivative, Hlong Exponent, const HString& Norm, const HString& Mode, Hlong Width, Hlong Height)

void HImage::GenDerivativeFilter(const char* Derivative, Hlong Exponent, const char* Norm, const char* Mode, Hlong Width, Hlong Height)

void HImage::GenDerivativeFilter(const wchar_t* Derivative, Hlong Exponent, const wchar_t* Norm, const wchar_t* Mode, Hlong Width, Hlong Height)   (Windows only)

static void HOperatorSet.GenDerivativeFilter(out HObject imageDerivative, HTuple derivative, HTuple exponent, HTuple norm, HTuple mode, HTuple width, HTuple height)

void HImage.GenDerivativeFilter(string derivative, int exponent, string norm, string mode, int width, int height)

def gen_derivative_filter(derivative: str, exponent: int, norm: str, mode: str, width: int, height: int) -> HObject

Description

gen_derivative_filtergen_derivative_filterGenDerivativeFilterGenDerivativeFilterGenDerivativeFiltergen_derivative_filter generates a derivative filter in the frequency domain. The derivative to be computed is determined by DerivativeDerivativeDerivativeDerivativederivativederivative. ExponentExponentExponentExponentexponentexponent specifies the exponent used in the reverse transform. It must be set to the same value that is used in fft_genericfft_genericFftGenericFftGenericFftGenericfft_generic. If fft_image_invfft_image_invFftImageInvFftImageInvFftImageInvfft_image_inv is used in the reverse transform, ExponentExponentExponentExponentexponentexponent = 1 must be used. However, since the derivative image typically contains negative values, fft_genericfft_genericFftGenericFftGenericFftGenericfft_generic should always be used for the reverse transform. To achieve a maximum overall efficiency of the filtering operation, the parameter NormNormNormNormnormnorm can be used to specify the normalization factor of the filter. If fft_genericfft_genericFftGenericFftGenericFftGenericfft_generic and NormNormNormNormnormnorm = 'n'"n""n""n""n""n" is used the normalization in the FFT can be avoided. ModeModeModeModemodemode 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_genericFftGenericFftGenericFftGenericfft_generic is used, 'dc_edge'"dc_edge""dc_edge""dc_edge""dc_edge""dc_edge" can be used to gain efficiency. If fft_imagefft_imageFftImageFftImageFftImagefft_image and fft_image_invfft_image_invFftImageInvFftImageInvFftImageInvfft_image_inv are used for filtering, NormNormNormNormnormnorm = 'none'"none""none""none""none""none" and ModeModeModeModemodemode = 'dc_center'"dc_center""dc_center""dc_center""dc_center""dc_center" must be used. If rft_genericrft_genericRftGenericRftGenericRftGenericrft_generic is used, ModeModeModeModemodemode = 'rft'"rft""rft""rft""rft""rft" must be used.

Execution Information

Parameters

ImageDerivativeImageDerivativeImageDerivativeImageDerivativeimageDerivativeimage_derivative (output_object)  image objectHImageHObjectHImageHobject * (complex)

Derivative filter as image in the frequency domain.

DerivativeDerivativeDerivativeDerivativederivativederivative (input_control)  string HTuplestrHTupleHtuple (string) (string) (HString) (char*)

Derivative to be computed.

Default value: 'x' "x" "x" "x" "x" "x"

Suggested values: 'x'"x""x""x""x""x", 'y'"y""y""y""y""y", 'xx'"xx""xx""xx""xx""xx", 'xy'"xy""xy""xy""xy""xy", 'yy'"yy""yy""yy""yy""yy", 'xxx'"xxx""xxx""xxx""xxx""xxx", 'xxy'"xxy""xxy""xxy""xxy""xxy", 'xyy'"xyy""xyy""xyy""xyy""xyy", 'yyy'"yyy""yyy""yyy""yyy""yyy"

ExponentExponentExponentExponentexponentexponent (input_control)  integer HTupleintHTupleHtuple (integer) (int / long) (Hlong) (Hlong)

Exponent used in the reverse transform.

Default value: 1

Suggested values: -1, 1

NormNormNormNormnormnorm (input_control)  string HTuplestrHTupleHtuple (string) (string) (HString) (char*)

Normalizing factor of the filter.

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

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

ModeModeModeModemodemode (input_control)  string HTuplestrHTupleHtuple (string) (string) (HString) (char*)

Location of the DC term in the frequency domain.

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

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

WidthWidthWidthWidthwidthwidth (input_control)  integer HTupleintHTupleHtuple (integer) (int / long) (Hlong) (Hlong)

Width of the image (filter).

Default value: 512

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

HeightHeightHeightHeightheightheight (input_control)  integer HTupleintHTupleHtuple (integer) (int / long) (Hlong) (Hlong)

Height of the image (filter).

Default value: 512

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

Example (HDevelop)

* Generate a smoothed derivative filter.
gen_gauss_filter (ImageGauss, Sigma, Sigma, 0, 'n', 'dc_edge', 512, 512)
convert_image_type (ImageGauss, ImageGaussComplex, 'complex')
gen_derivative_filter (ImageDerivX, 'x', 1, 'none', 'dc_edge', 512, 512)
mult_image (ImageGaussComplex, ImageDerivX, ImageDerivXGauss, 1, 0)
* Filter an image with the smoothed derivative filter.
fft_generic (Image, ImageFFT, 'to_freq', -1, 'none', 'dc_edge', 'complex')
convol_fft (ImageFFT, ImageDerivXGauss, Filtered)
fft_generic (Filtered, ImageX, 'from_freq', 1, 'none', 'dc_edge', 'real')

Result

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

Possible Predecessors

fft_imagefft_imageFftImageFftImageFftImagefft_image, fft_genericfft_genericFftGenericFftGenericFftGenericfft_generic, rft_genericrft_genericRftGenericRftGenericRftGenericrft_generic

Possible Successors

convol_fftconvol_fftConvolFftConvolFftConvolFftconvol_fft

See also

fft_image_invfft_image_invFftImageInvFftImageInvFftImageInvfft_image_inv, gen_gauss_filtergen_gauss_filterGenGaussFilterGenGaussFilterGenGaussFiltergen_gauss_filter, gen_mean_filtergen_mean_filterGenMeanFilterGenMeanFilterGenMeanFiltergen_mean_filter, gen_lowpassgen_lowpassGenLowpassGenLowpassGenLowpassgen_lowpass, gen_bandpassgen_bandpassGenBandpassGenBandpassGenBandpassgen_bandpass, gen_bandfiltergen_bandfilterGenBandfilterGenBandfilterGenBandfiltergen_bandfilter, gen_highpassgen_highpassGenHighpassGenHighpassGenHighpassgen_highpass

Module

Foundation