170 lines
3.9 KiB
C
170 lines
3.9 KiB
C
/* im_invfft
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*
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* Copyright: 1990, N. Dessipris.
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*
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* Author: Nicos Dessipris
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* Written on: 12/04/1990
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* Modified on :
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* 28/6/95 JC
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* - rewritten, based on new im_fwfft() code
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* 10/9/98 JC
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* - frees memory more quickly
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* 2/4/02 JC
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* - fftw code added
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* 13/7/02 JC
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* - Type reset
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* 27/2/03 JC
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* - tiny speed-up ... save 1 copy on write
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* 22/1/04 JC
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* - oops, fix for segv on wider than high fftw transforms
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* 3/11/04
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* - added fftw3 support
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* 7/2/10
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* - gtkdoc
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* 27/1/12
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* - better setting of interpretation
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* - remove own fft fallback code
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*/
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/*
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This file is part of VIPS.
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VIPS is free software; you can redistribute it and/or modify
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it under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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/*
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These files are distributed with VIPS - http://www.vips.ecs.soton.ac.uk
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*/
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#ifdef HAVE_CONFIG_H
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#include <config.h>
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#endif /*HAVE_CONFIG_H*/
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#include <vips/intl.h>
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#include <stdio.h>
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#include <math.h>
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#ifdef HAVE_FFTW
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#include <fftw3.h>
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#endif /*HAVE_FFTW*/
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#include <vips/vips.h>
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#include <vips/internal.h>
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#ifdef HAVE_FFTW
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/* Complex to complex inverse transform.
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*/
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static int
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invfft1( IMAGE *dummy, IMAGE *in, IMAGE *out )
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{
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fftw_plan plan;
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IMAGE *cmplx = im_open_local( out, "invfft1:1", "t" );
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/* We have to have a separate buffer for the planner to work on.
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*/
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double *planner_scratch = IM_ARRAY( dummy,
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VIPS_IMAGE_N_PELS( in ) * 2, double );
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/* Make dp complex image.
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*/
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if( !cmplx || im_pincheck( in ) || im_poutcheck( out ) )
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return( -1 );
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if( in->Coding != IM_CODING_NONE || in->Bands != 1 ) {
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im_error( "im_invfft",
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"%s", _( "one band uncoded only" ) );
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return( -1 );
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}
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if( im_clip2fmt( in, cmplx, IM_BANDFMT_DPCOMPLEX ) )
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return( -1 );
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/* Make the plan for the transform. Yes, they really do use nx for
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* height and ny for width.
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*/
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if( !(plan = fftw_plan_dft_2d( in->Ysize, in->Xsize,
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(fftw_complex *) planner_scratch,
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(fftw_complex *) planner_scratch,
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FFTW_BACKWARD,
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0 )) ) {
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im_error( "im_invfft",
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"%s", _( "unable to create transform plan" ) );
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return( -1 );
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}
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fftw_execute_dft( plan,
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(fftw_complex *) cmplx->data, (fftw_complex *) cmplx->data );
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fftw_destroy_plan( plan );
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cmplx->Type = IM_TYPE_B_W;
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/* Copy to out.
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*/
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if( im_copy( cmplx, out ) )
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return( -1 );
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return( 0 );
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}
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#else
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static int
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invfft1( IMAGE *dummy, IMAGE *in, IMAGE *out )
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{
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im_error( "im_invfft",
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"%s", _( "vips configured without FFT support" ) );
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return( -1 );
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}
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#endif
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/**
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* im_invfft:
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* @in: input image
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* @out: output image
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*
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* Transform an image from Fourier space to real space. The result is complex.
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* If you are OK with a real result, use im_invfftr() instead, it's quicker.
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*
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* VIPS uses the fftw3 or fftw2 Fourier transform libraries if possible. If
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* they were not available when VIPS was built, it falls back to it's own
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* FFT functions which are slow and only work for square images whose sides
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* are a power of two.
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*
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* See also: im_invfftr(), im_fwfft(), im_disp_ps().
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*
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* Returns: 0 on success, -1 on error.
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*/
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int
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im_invfft( IMAGE *in, IMAGE *out )
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{
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IMAGE *dummy = im_open( "im_invfft:1", "p" );
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if( !dummy )
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return( -1 );
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if( im__fftproc( dummy, in, out, invfft1 ) ) {
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im_close( dummy );
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return( -1 );
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}
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im_close( dummy );
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return( 0 );
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}
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