fft_image

fft_image_inv ( Image : ImageFFTInv : : )

Compute the inverse fast Fourier transform of an image.

fft_image_inv calculates the inverse Fourier transform of the input image (Image), i.e., it transforms the image back into the spatial domain. This corresponds to the call

     fft_generic(Image,ImageFFT,'from_freq',-1,'sqrt','dc_center') >
     convert_image_type(ImageFFT,ImageFFTInv,'byte') .

The result image is of type 'byte'.

Attention

The filtering is always done on the entire image, i.e., the region of the image is ignored. The images must be quadratic and the width and height must be a power of 2.

Parameters

`Image` (input_object)	image(-array) `->` object : complex
Input image.

`ImageFFTInv` (output_object)	image(-array) `->` object : byte
Inverse-Fourier-transformed image.

Example

fft_image(Image,&FFT);
gen_gabor(&Filter,1.4,0.4,1.0,1.5,512);
convol_gabor(FFT,Filter,&Gabor,&Hilbert);
fft_image_inv(Gabor,&GaborInv);
fft_image_inv(Hilbert,&HilbertInv);
energy_gabor(GaborInv,HilbertInv,&Energy);

Result

fft_image_inv returns 2 (H_MSG_TRUE) if the input image is of correct type and its width and height are a power of 2. If the input is empty the behaviour can be set via set_system(::'no_object_result',<Result>:). If necessary, an exception handling is raised.

Parallelization Information

fft_image_inv is reentrant and automatically parallelized (on tuple level).

Possible Predecessors

convol_fft, convol_gabor, fft_image

Possible Successors

convert_image_type, energy_gabor

Alternatives

fft_generic

Module

Image filters