136 lines
3.2 KiB
C
136 lines
3.2 KiB
C
/* @(#) Program to calculate the stdev of the differnce image
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* @(#) at a given displacement vector
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*
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* Written : 25/11/1987
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* Author : N. Dessipris
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* Updated : 2/12/1991
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* 22/7/93 JC
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* - im_incheck() added
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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., 51 Franklin Street, Fifth Floor, Boston, MA
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02110-1301 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 <glib/gi18n-lib.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <math.h>
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#include <vips/vips.h>
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#include <vips/vips7compat.h>
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#include <vips/internal.h>
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static int
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im__mean_std_int_buffer( int *buffer, int size,
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double *pmean, double *pstd )
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{
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double mean, std;
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register int i;
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int sumf;
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int temp;
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int *pbuffer;
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int sumf2;
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double correction; /* calulates the correction term for the variance */
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double variance; /* = (sumf2 - correction)/n */
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if (size <= 0) {
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im_error( "im_mean_std_int_buffer", "%s", _( "wrong args") );
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return(-1);
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}
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mean = 0.0; std = 0.0;
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sumf = 0; sumf2 = 0;
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pbuffer = buffer;
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for (i=0; i<size; i++) {
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temp = *pbuffer++;
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sumf += temp;
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sumf2 += (temp*temp);
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}
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correction = ((double)(sumf * sumf))/((double)size);
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mean = ((double)sumf)/((double)size);
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variance = ( sumf2 - correction)/((double)size);
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std = sqrt(variance);
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*pmean = mean;
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*pstd = std;
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return(0);
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}
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int im_dif_std(IMAGE *im, int xpos, int ypos, int xsize, int ysize, int dx, int dy, double *pmean, double *pstd)
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{
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PEL *input, *cpinput;
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double m, s;
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int *buf, *pbuf;
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int x, y;
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int ofst, bufsize;
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if( im_incheck( im ) )
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return( -1 );
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if ((im->Bands != 1)||(im->BandFmt != IM_BANDFMT_UCHAR)) {
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im_error( "im_dif_std", "%s", _( "Unable to accept input") );
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return(-1);}
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if ( (xpos + xsize + dx > im->Xsize)|| (ypos + ysize + dy > im->Ysize) ) {
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im_error( "im_dif_std", "%s", _( "wrong args") );
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return(-1); }
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bufsize = xsize * ysize;
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buf = (int *)calloc( (unsigned)bufsize, sizeof(int) );
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if ( buf == NULL ) {
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im_error( "im_dif_std", "%s", _( "calloc failed") );
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return(-1); }
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input = (PEL*)im->data;
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input += ( ypos * im->Xsize + xpos );
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ofst = dy * im->Xsize + dx;
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pbuf = buf;
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for ( y=0; y<ysize; y++ )
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{
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cpinput = input;
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input += im->Xsize;
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for ( x=0; x<xsize; x++ )
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{
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*pbuf++ = ((int)(*cpinput))-((int)(*(cpinput + ofst)));
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cpinput++;
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}
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}
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m = 0.0; s = 0.0;
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if( im__mean_std_int_buffer( buf, bufsize, &m, &s ) )
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return(-1);
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*pmean = m;
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*pstd = s;
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free((char*)buf);
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return(0);
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}
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