.TH IM_ROTQUAD 3 "07 July 1990"
.SH NAME
im_rotquad \- rotates the four quadrants of an image
.SH SYNOPSIS
.B #include <vips/vips.h>

.B int im_rotquad(in, out)
.br
.B IMAGE *in, *out;
.SH DESCRIPTION
im_rotquad rotates the four quadrants of the image held by the image
descriptor in and writes the result on the image descriptor out.

The function is used primarily to rotate a fourier transform in such a way
that the coordinate (0,0) is near the centre of the image, the so-called
optical transform.

The function operates on any input;
output has the same format, sizes and bands as input.
.SH RETURN VALUE
The function returns 0 on success and -1 on error.
.SH SEE ALSO
im_fwfft(3), im_invfft(3), im_scaleps(3).
.SH COPYRIGHT
.br
N. Dessipris
.SH AUTHOR
N. Dessipris \- 06/07/1990