**NAME**

im_disp_ps - creates a displayable power spectrum of an one band image

**SYNOPSIS**

**#include** **<vips/vips.h>**
**int** **im_disp_ps(in,** **out)**
**IMAGE** ***in,** ***out;**

**DESCRIPTION**

im_disp_ps() creates a displayable power spectrum of the image held by
the image descriptor in. The resultant unsigned char image is written
on the image descriptor out. Input should be one band image of any
non-complex type.
The function finds the fourier transform of the input (if in is not
complex) and then the amplitude power spectrum is created (im_c2ps(3)).
The power spectrum is passed through a non-linear transformation
(im_scaleps(3)). The final image has the four quadrants rotated in
such a way that the coordinate (0,0) is near the centre of the image
(im_rotquad(3)).
Input should be a square image with size power of 2. The maximum size
of the input image is dictated by the available RAM.

**RETURN** **VALUE**

The function returns 0 on success and -1 on error.

**SEE ALSO**

im_fwfft(3), im_c2ps(3), im_scaleps(3), im_rotquad(3).

**COPYRIGHT**

N. Dessipris

**AUTHOR**

N. Dessipris - 23/05/1991
23 May 1991