correlation_fftcorrelation_fftCorrelationFftCorrelationFftcorrelation_fft (Operator)

Name

correlation_fftcorrelation_fftCorrelationFftCorrelationFftcorrelation_fft — Compute the correlation of two images in the frequency domain.

Signature

correlation_fft(ImageFFT1, ImageFFT2 : ImageCorrelation : : )

Description

correlation_fftcorrelation_fftCorrelationFftCorrelationFftCorrelationFftcorrelation_fft calculates the correlation of the Fourier-transformed input images in the frequency domain. The correlation is calculated by multiplying ImageFFT1ImageFFT1ImageFFT1ImageFFT1imageFFT1image_fft1 with the complex conjugate of ImageFFT2ImageFFT2ImageFFT2ImageFFT2imageFFT2image_fft2. It should be noted that in order to achieve a correct scaling of the correlation in the spatial domain, the operators fft_genericfft_genericFftGenericFftGenericFftGenericfft_generic or rft_genericrft_genericRftGenericRftGenericRftGenericrft_generic with NormNormNormNormnormnorm = 'none'"none""none""none""none""none" must be used for the forward transform and fft_genericfft_genericFftGenericFftGenericFftGenericfft_generic or rft_genericrft_genericRftGenericRftGenericRftGenericrft_generic with NormNormNormNormnormnorm = 'n'"n""n""n""n""n" for the reverse transform. If ImageFFT1ImageFFT1ImageFFT1ImageFFT1imageFFT1image_fft1 and ImageFFT2ImageFFT2ImageFFT2ImageFFT2imageFFT2image_fft2 contain the same number of images, the corresponding images are correlated pairwise. Otherwise, ImageFFT2ImageFFT2ImageFFT2ImageFFT2imageFFT2image_fft2 must contain only one single image. In this case, the correlation is performed for each image of ImageFFT1ImageFFT1ImageFFT1ImageFFT1imageFFT1image_fft1 with ImageFFT2ImageFFT2ImageFFT2ImageFFT2imageFFT2image_fft2 .

Attention

The filtering is always performed on the entire image, i.e., the domain of the image is ignored.

Execution Information

Multithreading type: reentrant (runs in parallel with non-exclusive operators).
Multithreading scope: global (may be called from any thread).
Automatically parallelized on tuple level.
Automatically parallelized on channel level.

Parameters

ImageFFT1ImageFFT1ImageFFT1ImageFFT1imageFFT1image_fft1 (input_object) (multichannel-)image(-array) → object (complex)

Fourier-transformed input image 1.

ImageFFT2ImageFFT2ImageFFT2ImageFFT2imageFFT2image_fft2 (input_object) (multichannel-)image(-array) → object (complex)

Fourier-transformed input image 2.

Number of elements: ImageFFT2 == ImageFFT1 || ImageFFT2 == 1

ImageCorrelationImageCorrelationImageCorrelationImageCorrelationimageCorrelationimage_correlation (output_object) image(-array) → object (complex)

Correlation of the input images in the frequency domain.

Example (HDevelop)

* Compute the auto-correlation of an image.
get_image_size(Image,Width,Height)
rft_generic(Image,ImageFFT,'to_freq','none','complex',Width)
correlation_fft(ImageFFT,ImageFFT,Correlation)
rft_generic(Correlation,AutoCorrelation,'from_freq','n','real',Width)

Result

correlation_fftcorrelation_fftCorrelationFftCorrelationFftCorrelationFftcorrelation_fft returns 2 (H_MSG_TRUE) if all parameters are correct. If the input is empty the behavior can be set via 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>). If necessary, an exception is raised.

Possible Predecessors

fft_genericfft_genericFftGenericFftGenericFftGenericfft_generic, fft_imagefft_imageFftImageFftImageFftImagefft_image, rft_genericrft_genericRftGenericRftGenericRftGenericrft_generic

Possible Successors

fft_genericfft_genericFftGenericFftGenericFftGenericfft_generic, fft_image_invfft_image_invFftImageInvFftImageInvFftImageInvfft_image_inv, rft_genericrft_genericRftGenericRftGenericRftGenericrft_generic

Alternatives

phase_correlation_fftphase_correlation_fftPhaseCorrelationFftPhaseCorrelationFftPhaseCorrelationFftphase_correlation_fft

Module

Foundation

Operators