rft_genericrft_genericRftGenericRftGenericrft_generic（算子）

名称

rft_genericrft_genericRftGenericRftGenericrft_generic — 计算图像的实值快速傅里叶变换。

签名

描述

rft_genericrft_genericRftGenericRftGenericRftGenericrft_generic computes the fast Fourier transform of the input image ImageImageImageImageimageimage. In contrast to fft_genericfft_genericFftGenericFftGenericFftGenericfft_generic, fft_imagefft_imageFftImageFftImageFftImagefft_image, and fft_image_invfft_image_invFftImageInvFftImageInvFftImageInvfft_image_inv, the fact that the input image in the forward transform is a real-valued image (i.e., not a complex image) is used. In this case, the complex output image has a redundancy. The values in the right half of the image are the complex conjugates of the corresponding values in the left half of the image. Consequently, runtime and memory can be saved by only computing and storing the left half of the complex image.

The parameter ResultTypeResultTypeResultTypeResultTyperesultTyperesult_type can be used to specify the result image type of the reverse transform (DirectionDirectionDirectionDirectiondirectiondirection = 'from_freq'"from_freq""from_freq""from_freq""from_freq""from_freq"). In the forward transform (DirectionDirectionDirectionDirectiondirectiondirection = 'to_freq'"to_freq""to_freq""to_freq""to_freq""to_freq"), ResultTypeResultTypeResultTypeResultTyperesultTyperesult_type must be set to 'complex'"complex""complex""complex""complex""complex".

The parameter direction determines whether the transform should be performed to the frequency domain or back into the spatial domain. For DirectionDirectionDirectionDirectiondirectiondirection = 'to_freq'"to_freq""to_freq""to_freq""to_freq""to_freq" the input image must have a real-valued type, i.e., a complex image may not be used as input. All image types that can be converted into an image of type real are supported. In this case, the output is a complex image of dimension (w/2+1)*h, where w and h are the width and height of the input image. In this mode, the exponent -1 is used in the transform (see fft_genericfft_genericFftGenericFftGenericFftGenericfft_generic). For DirectionDirectionDirectionDirectiondirectiondirection = 'from_freq'"from_freq""from_freq""from_freq""from_freq""from_freq", the input image must be complex. In this case, the size of the input image is insufficient to determine the size of the output image. This must be done by setting WidthWidthWidthWidthwidthwidth to a valid value, i.e., to 2*w-2 or 2*w-1, where w is the width of the complex image. In this mode, the exponent 1 is used in the transform.

The normalizing factor can be set with NormNormNormNormnormnorm, and can take on the values 'none'"none""none""none""none""none", 'sqrt'"sqrt""sqrt""sqrt""sqrt""sqrt" and 'n'"n""n""n""n""n". The user must ensure the consistent use of the parameters. This means that the normalizing factors used for the forward and backward transform must yield w*h when multiplied.

注意

The transformation is always performed for the entire image, i.e., the domain of the image is ignored.

执行信息

• 多线程类型：可重入（与非独占算子并行运行）。
• 多线程作用域：全局（可从任何线程调用）。
• 在元组级别上自动并行化。
• 在通道级别上自动并行化。
• 在内部数据级别上自动并行化。

参数

结果

rft_genericrft_genericRftGenericRftGenericRftGenericrft_generic 在所有参数正确时返回 2 ( H_MSG_TRUE )。当输入为空时，可设置行为通过算子 set_system(::'no_object_result',<Result>:)set_system("no_object_result",<Result>)SetSystem("no_object_result",<Result>)SetSystem("no_object_result",<Result>)SetSystem("no_object_result",<Result>)set_system("no_object_result",<Result>)。如有必要，则抛出异常。

可能的前趋

optimize_rft_speedoptimize_rft_speedOptimizeRftSpeedOptimizeRftSpeedOptimizeRftSpeedoptimize_rft_speed, read_fft_optimization_dataread_fft_optimization_dataReadFftOptimizationDataReadFftOptimizationDataReadFftOptimizationDataread_fft_optimization_data

可能的后继

convol_fftconvol_fftConvolFftConvolFftConvolFftconvol_fft, correlation_fftcorrelation_fftCorrelationFftCorrelationFftCorrelationFftcorrelation_fft, phase_correlation_fftphase_correlation_fftPhaseCorrelationFftPhaseCorrelationFftPhaseCorrelationFftphase_correlation_fft, convert_image_typeconvert_image_typeConvertImageTypeConvertImageTypeConvertImageTypeconvert_image_type, power_bytepower_bytePowerBytePowerBytePowerBytepower_byte, power_realpower_realPowerRealPowerRealPowerRealpower_real, power_lnpower_lnPowerLnPowerLnPowerLnpower_ln, phase_degphase_degPhaseDegPhaseDegPhaseDegphase_deg, phase_radphase_radPhaseRadPhaseRadPhaseRadphase_rad

替代

fft_genericfft_genericFftGenericFftGenericFftGenericfft_generic, fft_imagefft_imageFftImageFftImageFftImagefft_image, fft_image_invfft_image_invFftImageInvFftImageInvFftImageInvfft_image_inv

模块

基础