vips_fwfft ()

int
vips_fwfft (VipsImage *in,
            VipsImage **out,
            ...);

Transform an image to Fourier space.

VIPS uses the fftw Fourier Transform library. If this library was not available when VIPS was configured, these functions will fail.

See also: vips_invfft().

vips_invfft ()

int
vips_invfft (VipsImage *in,
             VipsImage **out,
             ...);

Optional arguments:

real : only output the real part

Transform an image from Fourier space to real space. The result is complex. If you are OK with a real result, set real , it's quicker.

VIPS uses the fftw Fourier Transform library. If this library was not available when VIPS was configured, these functions will fail.

See also: vips_fwfft().

vips_freqmult ()

int
vips_freqmult (VipsImage *in,
               VipsImage *mask,
               VipsImage **out,
               ...);

Multiply in by mask in Fourier space.

in is transformed to Fourier space, multipled with mask , then transformed back to real space. If in is already a complex image, just multiply then inverse transform.

See also: vips_invfft(), vips_mask_ideal().

vips_spectrum ()

int
vips_spectrum (VipsImage *in,
               VipsImage **out,
               ...);

Make a displayable (ie. 8-bit unsigned int) power spectrum.

If in is non-complex, it is transformed to Fourier space. Then the absolute value is passed through vips_scale() in log mode, and vips_wrap().

See also: vips_fwfft(), vips_scale(), vips_wrap().

vips_phasecor ()

int
vips_phasecor (VipsImage *in1,
               VipsImage *in2,
               VipsImage **out,
               ...);

Convert the two input images to Fourier space, calculate phase-correlation, back to real space.

See also: vips_fwfft(), vips_cross_phase(),