.TH IM_FOURFLT 3 "10 May 1991"
.SH NAME
im_freqflt \- filters an image with a float filter mask in the frequency domain
.SH SYNOPSIS
.B #include <vips/vips.h>

.B int im_freqflt(in, filtermask, out)
.br
IMAGE *in, *filtermask, *out;
.SH DESCRIPTION
im_freqflt() performs filtering in the frequency domain of the input image
held by the image descriptor in with a mask held by the descriptor filtermask
and writes the result on the image descriptor out.

Image sizes should be power of two and less or equal to 512.  All images
should be one channel square images.  Image filtermask is a non-complex one
channel image created by im_create_fmask().  Input image can be any type.  If
input is complex, in and filtermask are multiplied using the function
im_cmultim(3).

If input is not complex then it is transformed into the frequency domain and
then it is multiplied with the filtermask.  In the latter case the result is
inverse fourier transformed and clipped to the input image format using the
function im_clip2fmt(3).
.SH RETURN VALUE
The function returns 0 on success and -1 on error.
.SH BUGS
The function has not been fully tested.
.SH SEE\ ALSO
im_fwfft(3), im_invfft(3), im_create_fmask(3), im_cmultim(3).
.SH COPYRIGHT
.br
N. Dessipris
.SH AUTHOR
N. Dessipris \- 10/05/1991