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