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