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/* im_cross_phase.c
*
* Copyright: 2008, Nottingham Trent University
*
* Author: Tom Vajzovic
* Written on: 2008-01-09
*
* 2008-02-04 tcv:
* - exp( i.th ) == cos(th)+i.sin(th) NOT sin(th)+i.cos(th)
* - add quadratic version (ifdef'd out ATM - still using trigonometric one)
* 2/9/09
* - gtk-doc comment
*/
/*
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 <stdlib.h>
#include <math.h>
#include <vips/vips.h>
/* There doesn't seem to be much difference in speed between these two methods (on an Athlon64),
* so I use the modulus argument version, since atan2() is in c89 but hypot() is c99.
*
* If you think that it might be faster on your platform, uncomment the following:
*/
#define USE_MODARG_DIV
#ifdef USE_MODARG_DIV
#define COMPLEX_PHASE_FN( TYPE, ABS ) \
static void \
complex_phase_ ## TYPE ( void *in1, void *in2, void *out, int n, void *im, void *unrequired ){ \
\
TYPE *X= (TYPE*) in1; \
TYPE *Y= (TYPE*) in2; \
TYPE *Z= (TYPE*) out; \
TYPE *Z_stop= Z + 2 * n * ((IMAGE*)im)-> Bands; \
\
for( ; Z < Z_stop; X+= 2, Y+= 2 ){ \
double arg= atan2( X[1], X[0] ) - atan2( Y[1], Y[0] ); \
*Z++= cos( arg ); \
*Z++= sin( arg ); \
} \
}
#else /* USE_MODARG_DIV */
#define COMPLEX_PHASE_FN( TYPE, ABS ) \
static void \
complex_phase_ ## TYPE ( void *in1, void *in2, void *out, int n, void *im, void *unrequired ){ \
\
TYPE *X= (TYPE*) in1; \
TYPE *Y= (TYPE*) in2; \
TYPE *Z= (TYPE*) out; \
TYPE *Z_stop= Z + 2 * n * ((IMAGE*)im)-> Bands; \
\
for( ; Z < Z_stop; X+= 2, Y+= 2 ) \
\
if( ABS( Y[0] ) > ABS( Y[1] )){ \
double a= Y[1] / Y[0]; \
double b= Y[0] + Y[1] * a; \
double re= ( X[0] + X[1] * a ) / b; \
double im= ( X[1] - X[0] * a ) / b; \
double mod= im__hypot( re, im ); \
*Z++= re / mod; \
*Z++= im / mod; \
} \
else { \
double a= Y[0] / Y[1]; \
double b= Y[1] + Y[0] * a; \
double re= ( X[0] * a + X[1] ) / b; \
double im= ( X[1] * a - X[0] ) / b; \
double mod= im__hypot( re, im ); \
*Z++= re / mod; \
*Z++= im / mod; \
} \
}
#endif /* USE_MODARG_DIV */
COMPLEX_PHASE_FN( float, fabsf )
COMPLEX_PHASE_FN( double, fabs )
/**
* im_cross_phase:
* @a: input #IMAGE 1
* @b: input #IMAGE 2
* @out: output #IMAGE
*
* Find the phase of the cross power spectrum of two complex images,
* expressed as a complex image where the modulus of each pixel is
* one.
*
* I.E. find (a.b*)/|a.b*| where
* . represents complex multiplication
* * represents the complex conjugate
* || represents the complex modulus
*
* See also: im_multiply(), im_sign().
*
* Returns: 0 on success, -1 on error
*/
int im_cross_phase( IMAGE *a, IMAGE *b, IMAGE *out ){
#define FUNCTION_NAME "im_phase"
if( im_pincheck( a ) || im_pincheck( b ) || im_poutcheck( out ))
return -1;
if( im_check_size_same( FUNCTION_NAME, a, b ) ||
im_check_bands_same( FUNCTION_NAME, a, b ) ||
im_check_format_same( FUNCTION_NAME, a, b ) ||
im_check_uncoded( FUNCTION_NAME, a ) ||
im_check_uncoded( FUNCTION_NAME, b ) ||
im_check_complex( FUNCTION_NAME, a ) ||
im_check_complex( FUNCTION_NAME, b ) )
return -1;
return im_cp_descv( out, a, b, NULL ) || im_wraptwo( a, b, out,
IM_BANDFMT_COMPLEX == a-> BandFmt ? complex_phase_float : complex_phase_double, a, NULL );
}
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