libvips/libsrc/arithmetic/im_maxpos.c

152 lines
3.8 KiB
C

/* @(#) Function to find the maximum of an image. Works for any
* @(#) image type. Returns a double and the location of max.
* @(#)
* @(#) Function im_maxpos() assumes that input
* @(#) is either memory mapped or in a buffer.
* @(#)
* @(#) int im_maxpos(in, xpos, ypos, max)
* @(#) IMAGE *in;
* @(#) int *xpos, *ypos;
* @(#) double *max;
* @(#)
* @(#) Returns 0 on success and -1 on error
*
* Copyright: 1990, J. Cupitt
*
* Author: J. Cupitt
* Written on: 02/05/1990
* Modified on : 18/03/1991, N. Dessipris
* 23/11/92: J.Cupitt - correct result for more than 1 band now.
* 23/7/93 JC
* - im_incheck() call added
* 20/6/95 JC
* - now returns double for value, like im_max()
*/
/*
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 <assert.h>
#include <vips/vips.h>
#ifdef WITH_DMALLOC
#include <dmalloc.h>
#endif /*WITH_DMALLOC*/
/* Useful: Call a macro with the name, type pairs for all VIPS functions.
*/
#define im_for_all_types() \
case IM_BANDFMT_UCHAR: loop(unsigned char); break; \
case IM_BANDFMT_CHAR: loop(signed char); break; \
case IM_BANDFMT_USHORT: loop(unsigned short); break; \
case IM_BANDFMT_SHORT: loop(signed short); break; \
case IM_BANDFMT_UINT: loop(unsigned int); break; \
case IM_BANDFMT_INT: loop(signed int); break; \
case IM_BANDFMT_FLOAT: loop(float); break; \
case IM_BANDFMT_DOUBLE: loop(double); break; \
case IM_BANDFMT_COMPLEX: loopcmplx(float); break; \
case IM_BANDFMT_DPCOMPLEX: loopcmplx(double); break;
/* Find the position of the maximum of an image. Take any format, returns a
* float and its position.
*/
int
im_maxpos( IMAGE *in, int *xpos, int *ypos, double *out )
{
double m;
int xp=0, yp=0;
int os;
/* Check our args. */
if( im_incheck( in ) )
return( -1 );
if( in->Coding != IM_CODING_NONE ) {
im_error( "im_maxpos", "%s", _( "not uncoded" ) );
return( -1 );
}
/* What type? First define the loop we want to perform for all types. */
#define loop(TYPE) \
{ TYPE *p = (TYPE *) in->data; \
int x, y; \
m = (double) *p; \
\
for ( y=0; y<in->Ysize; y++ ) \
for ( x=0; x<os; x++ ) {\
if( (double) *p > m ) {\
m = (double) *p; \
xp = x; yp = y; \
}\
p++ ;\
}\
}
#define loopcmplx(TYPE) \
{ TYPE *p = (TYPE *) in->data; \
double re=(double)*p;\
double im=(double)*(p+1);\
double mod = re * re + im * im;\
int x, y; \
m = mod; \
\
for ( y=0; y<in->Ysize; y++ ) \
for ( x=0; x<os; x++ ) {\
re = (double)*p++; im = (double)*p++; \
mod = re * re + im * im; \
if( mod > m ) {\
m = mod; \
xp = x; yp = y; \
}\
}\
}
/* Now generate code for all types. */
os = in->Xsize * in->Bands;
switch( in->BandFmt ) {
im_for_all_types();
default: {
assert( 0 );
return( -1 );
}
}
/* Return maxima and position of maxima. Nasty: we divide the xpos by
* the number of bands to get the position in pixels.
*/
*out = m;
*xpos = xp / in->Bands;
*ypos = yp;
return( 0 );
}