correlation_fftcorrelation_fftcorrelation_fftCorrelationFftCorrelationFft (Operator)

Name

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

Signature

Description

correlation_fftcorrelation_fftcorrelation_fftCorrelationFftCorrelationFft calculates the correlation of the Fourier-transformed input images in the frequency domain. The correlation is calculated by multiplying ImageFFT1ImageFFT1ImageFFT1ImageFFT1imageFFT1 with the complex conjugate of ImageFFT2ImageFFT2ImageFFT2ImageFFT2imageFFT2. It should be noted that in order to achieve a correct scaling of the correlation in the spatial domain, the operators fft_genericfft_genericfft_genericFftGenericFftGeneric or rft_genericrft_genericrft_genericRftGenericRftGeneric with Norm = 'none'"none""none""none""none" must be used for the forward transform and fft_genericfft_genericfft_genericFftGenericFftGeneric or rft_genericrft_genericrft_genericRftGenericRftGeneric with Norm = 'n'"n""n""n""n" for the reverse transform. If ImageFFT1ImageFFT1ImageFFT1ImageFFT1imageFFT1 and ImageFFT2ImageFFT2ImageFFT2ImageFFT2imageFFT2 contain the same number of images, the corresponding images are correlated pairwise. Otherwise, ImageFFT2ImageFFT2ImageFFT2ImageFFT2imageFFT2 must contain only one single image. In this case, the correlation is performed for each image of ImageFFT1ImageFFT1ImageFFT1ImageFFT1imageFFT1 with ImageFFT2ImageFFT2ImageFFT2ImageFFT2imageFFT2 .

Attention

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

Parallelization

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

Parameters

Example (HDevelop)

* Compute the auto-correlation of an image.
get_image_pointer1(Image,Pointer,Type,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

convol_fftconvol_fftconvol_fftConvolFftConvolFft 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>)set_system("no_object_result",<Result>)SetSystem("no_object_result",<Result>)SetSystem("no_object_result",<Result>). If necessary, an exception is raised.

Possible Predecessors

fft_genericfft_genericfft_genericFftGenericFftGeneric, fft_imagefft_imagefft_imageFftImageFftImage, rft_genericrft_genericrft_genericRftGenericRftGeneric

Possible Successors

fft_genericfft_genericfft_genericFftGenericFftGeneric, fft_image_invfft_image_invfft_image_invFftImageInvFftImageInv, rft_genericrft_genericrft_genericRftGenericRftGeneric

Module

Foundation