|  |  |  | VIPS Reference Manual |  | 
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| Top | Description | ||||
int vips_fwfft (VipsImage *in,VipsImage **out,...); int vips_invfft (VipsImage *in,VipsImage **out,...); int vips_freqmult (VipsImage *in,VipsImage *mask,VipsImage **out,...); int vips_spectrum (VipsImage *in,VipsImage **out,...); int vips_phasecor (VipsImage *in1,VipsImage *in2,VipsImage **out,...);
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().
| 
 | input image | 
| 
 | output image | 
| 
 | NULL-terminated list of optional named arguments | 
| Returns : | 0 on success, -1 on error. | 
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().
| 
 | input image | 
| 
 | output image | 
| 
 | NULL-terminated list of optional named arguments | 
| Returns : | 0 on success, -1 on error. | 
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().
| 
 | input image | 
| 
 | mask image | 
| 
 | output image | 
| 
 | NULL-terminated list of optional named arguments | 
| Returns : | 0 on success, -1 on error. | 
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().
| 
 | input image | 
| 
 | output image | 
| 
 | NULL-terminated list of optional named arguments | 
| Returns : | 0 on success, -1 on error. | 
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(),
| 
 | first input image | 
| 
 | second input image | 
| 
 | output image | 
| 
 | NULL-terminated list of optional named arguments | 
| Returns : | 0 on success, -1 on error. |