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IM_FOURFLT(3)                                                    IM_FOURFLT(3)




NAME

       im_freqflt - filters an image with a float filter mask in the frequency
       domain


SYNOPSIS

       #include <vips/vips.h>

       int im_freqflt(in, filtermask, out)
       IMAGE *in, *filtermask, *out;


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 descrip-
       tor 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).


RETURN VALUE

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


BUGS

       The function has not been fully tested.


SEE ALSO

       im_fwfft(3), im_invfft(3), im_create_fmask(3), im_cmultim(3).


COPYRIGHT

       N. Dessipris


AUTHOR

       N. Dessipris - 10/05/1991



                                  10 May 1991                    IM_FOURFLT(3)

im_freqflt 7.14.5 - Generated Sun Sep 7 09:55:25 CDT 2008
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