gen_derivative_filtergen_derivative_filterGenDerivativeFilterGenDerivativeFilter (Operator)
Name
gen_derivative_filtergen_derivative_filterGenDerivativeFilterGenDerivativeFilter — Generate a derivative filter in the frequency domain.
Signature
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)
Description
gen_derivative_filtergen_derivative_filterGenDerivativeFilterGenDerivativeFilterGenDerivativeFilter generates a derivative filter in the
frequency domain. The derivative to be computed is determined by
DerivativeDerivativeDerivativeDerivativederivative. ExponentExponentExponentExponentexponent specifies the exponent used
in the reverse transform. It must be set to the same value that is
used in fft_genericfft_genericFftGenericFftGenericFftGeneric. If fft_image_invfft_image_invFftImageInvFftImageInvFftImageInv is used in
the reverse transform, ExponentExponentExponentExponentexponent = 1 must be
used. However, since the derivative image typically contains
negative values, fft_genericfft_genericFftGenericFftGenericFftGeneric should always be used for the
reverse transform. 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.
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
ImageDerivativeImageDerivativeImageDerivativeImageDerivativeimageDerivative (output_object) image → objectHImageHImageHobject * (complex)
Derivative filter as image in the frequency domain.
DerivativeDerivativeDerivativeDerivativederivative (input_control) string → HTupleHTupleHtuple (string) (string) (HString) (char*)
Derivative to be computed.
Default value:
'x'
"x"
"x"
"x"
"x"
Suggested values: 'x'"x""x""x""x", 'y'"y""y""y""y", 'xx'"xx""xx""xx""xx", 'xy'"xy""xy""xy""xy", 'yy'"yy""yy""yy""yy", 'xxx'"xxx""xxx""xxx""xxx", 'xxy'"xxy""xxy""xxy""xxy", 'xyy'"xyy""xyy""xyy""xyy", 'yyy'"yyy""yyy""yyy""yyy"
ExponentExponentExponentExponentexponent (input_control) integer → HTupleHTupleHtuple (integer) (int / long) (Hlong) (Hlong)
Exponent used in the reverse transform.
Default value: 1
Suggested values: -1, 1
NormNormNormNormnorm (input_control) string → HTupleHTupleHtuple (string) (string) (HString) (char*)
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 → HTupleHTupleHtuple (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"
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 → HTupleHTupleHtuple (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
HeightHeightHeightHeightheight (input_control) integer → HTupleHTupleHtuple (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_filterGenDerivativeFilterGenDerivativeFilterGenDerivativeFilter returns 2 (H_MSG_TRUE) if all parameters are
correct. If necessary, an exception is raised.
Possible Predecessors
fft_imagefft_imageFftImageFftImageFftImage,
fft_genericfft_genericFftGenericFftGenericFftGeneric,
rft_genericrft_genericRftGenericRftGenericRftGeneric
Possible Successors
convol_fftconvol_fftConvolFftConvolFftConvolFft
See also
fft_image_invfft_image_invFftImageInvFftImageInvFftImageInv,
gen_gauss_filtergen_gauss_filterGenGaussFilterGenGaussFilterGenGaussFilter,
gen_mean_filtergen_mean_filterGenMeanFilterGenMeanFilterGenMeanFilter,
gen_lowpassgen_lowpassGenLowpassGenLowpassGenLowpass,
gen_bandpassgen_bandpassGenBandpassGenBandpassGenBandpass,
gen_bandfiltergen_bandfilterGenBandfilterGenBandfilterGenBandfilter,
gen_highpassgen_highpassGenHighpassGenHighpassGenHighpass
Module
Foundation