libvips/libsrc/conversion/im_c2amph.c
2007-08-29 16:23:50 +00:00

143 lines
3.2 KiB
C

/* @(#) Functions which transforms the real and the imaginary parts of
* @(#) a complex image into amplitude and phase.
* @(#) Input image is either memory mapped or in a buffer.
* @(#) Used to display an inverse complex Fourier transform
* @(#)
* @(#) int im_c2amph(in, out)
* @(#) IMAGE *in, *out;
* @(#)
* @(#) All functions return 0 on success and -1 on error
* @(#)
*
* Copyright: 1990, N. Dessipris.
*
* Author: Nicos Dessipris
* Written on: 12/02/1990
* Modified on : 09/05/1990
* 15/6/93 JC
* - stupid stupid includes and externs fixed
* - I have been editing for 1 1/2 hours and I'm still drowning in
* rubbish extetrnshh
* 13/12/94 JC
* - modernised
* 9/7/02 JC
* - degree output, for consistency
* - slightly better behaviour in edge cases
*/
/*
This file is part of VIPS.
VIPS is free software; you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
/*
These files are distributed with VIPS - http://www.vips.ecs.soton.ac.uk
*/
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif /*HAVE_CONFIG_H*/
#include <vips/intl.h>
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <vips/vips.h>
#ifdef WITH_DMALLOC
#include <dmalloc.h>
#endif /*WITH_DMALLOC*/
#define loop(TYPE) \
{\
TYPE *p = (TYPE *) in;\
TYPE *q = (TYPE *) out;\
int x;\
\
for( x = 0; x < n; x++ ) {\
double re = p[0];\
double im = p[1];\
double am, ph;\
\
am = sqrt( re * re + im * im );\
\
if( re == 0 ) { \
if( im < 0.0 ) \
ph = 270; \
else if( im == 0.0 ) \
ph = 0; \
else \
ph = 90; \
} \
else { \
double t = atan( im / re ); \
\
if( re > 0.0 ) \
if( im < 0.0 ) \
ph = IM_DEG( t + IM_PI * 2.0 ); \
else \
ph = IM_DEG( t ); \
else \
ph = IM_DEG( t + IM_PI ); \
} \
\
q[0] = am; \
q[1] = ph; \
\
p += 2; \
q += 2; \
}\
}
/* c2amph buffer processor.
*/
static void
buffer_c2amph( void *in, void *out, int w, IMAGE *im )
{
int n = w * im->Bands;
switch( im->BandFmt ) {
case IM_BANDFMT_DPCOMPLEX: loop(double); break;
case IM_BANDFMT_COMPLEX: loop(float); break;
default:
error_exit( "buffer_c2amph: internal error" );
}
}
int
im_c2amph( IMAGE *in, IMAGE *out )
{
if( in->Coding != IM_CODING_NONE || !im_iscomplex( in ) ) {
im_errormsg( "im_c2amph: input should be uncoded complex" );
return( -1 );
}
if( im_cp_desc( out, in ) )
return( -1 );
/* Do the processing.
*/
if( im_wrapone( in, out,
(im_wrapone_fn) buffer_c2amph, in, NULL ) )
return( -1 );
return( 0 );
}