libvips/libsrc/mosaicing/im_chkpair.c

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2007-08-29 18:23:50 +02:00
/* @(#) Functions which improve the selection of two ttie points pairs in two
* @(#) images, by estimating the correlation coefficient given in page 426
* @(#) 2nd edn of the book Digital Image processing Gonzalez and Wintz
* @(#) The function works as follows:
* @(#) It expects to receive nopoints pairs (coordinates) of points
* @(#) corresponding to ref and sec.
* @(#) The coordinates of the pairs are in arrays x1,y1 and x2,y2
* @(#) After that the program reads a region of 2*halfcorsize +1 pels centered
* @(#) at point (x1, y1) and looks around
* @(#) an area 2*halfareasize+1 centered at point (x2, y2).
* @(#) For each point in this 2*halfareasize+1,
* @(#) the program reads the corresponding
* @(#) image2 values in a region of 2*halfcorsize+1 pels centered at this point
* @(#) and calculates the corresponding correlation coefficients.
* @(#) The result is stored in a the array
* @(#) corcoef[(2*halfareasize+1)(2*halfareasize+1)]. Within this window, the
* @(#) max correlation coefficient is estimated and its corresponding
* @(#) (x, y) coordinates are returned in (x2, y2).
* @(#) The purpose of this function is to improve the selection of
* @(#) control points entered in (x1, y1)
* @(#) Both input images should are either memory mapped or in a buffer.
* @(#) The variable bandno should be between 1 and ref->Bands
* @(#) The program fills the dx[] and dy[] arrays before returning.
* @(#)
* @(#) int im__chkpair( ref, sec, bandno, points )
* @(#) IMAGE *ref, *sec;
* @(#) int bandno;
* @(#) TIE_POINTS *points;
* @(#)
* @(#) Returns 0 on sucess and -1 on error.
*
* Copyright: 1990, N. Dessipris.
*
* Author: Nicos Dessipris
* Written on: 02/05/1990
* Modified on : 18/04/1991
* 8/7/93 JC
* - allows IM_CODING_LABQ coding
* - now calls im_incheck()
* 13/7/95 JC
* - rewritten
* - now uses im_spcor()
* 13/8/96 JC
* - order of args changed to help C++ API
*/
/*
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 "mosaic.h"
#ifdef WITH_DMALLOC
#include <dmalloc.h>
#endif /*WITH_DMALLOC*/
/* Find position of sec within ref. Search around point xsec, ysec for the
* best match for the area around xref, yref. Search an area of size
* hsearchsize for an of size hwindowsize.
*
* Return a new value for xsec, ysec and the correlation at that point.
*
* Also used by im_match_linear(), im_match_linear_search(), etc.
*/
int
im_correl( IMAGE *ref, IMAGE *sec,
int xref, int yref, int xsec, int ysec,
int hwindowsize, int hsearchsize,
double *correlation, int *x, int *y )
{
IMAGE *surface = im_open( "surface", "t" );
IMAGE *t1, *t2, *t3, *t4;
Rect refr, secr;
Rect winr, srhr;
Rect wincr, srhcr;
if( !surface ||
!(t1 = im_open_local( surface, "correlate:1", "p" )) ||
!(t2 = im_open_local( surface, "correlate:1", "p" )) ||
!(t3 = im_open_local( surface, "correlate:1", "p" )) ||
!(t4 = im_open_local( surface, "correlate:1", "p" )) )
return( -1 );
/* Find position of window and search area, and clip against image
* size.
*/
refr.left = 0;
refr.top = 0;
refr.width = ref->Xsize;
refr.height = ref->Ysize;
winr.left = xref - hwindowsize;
winr.top = yref - hwindowsize;
winr.width = hwindowsize*2 + 1;
winr.height = hwindowsize*2 + 1;
im_rect_intersectrect( &refr, &winr, &wincr );
secr.left = 0;
secr.top = 0;
secr.width = sec->Xsize;
secr.height = sec->Ysize;
srhr.left = xsec - hsearchsize;
srhr.top = ysec - hsearchsize;
srhr.width = hsearchsize*2 + 1;
srhr.height = hsearchsize*2 + 1;
im_rect_intersectrect( &secr, &srhr, &srhcr );
/* Extract window and search area.
*/
if( im_extract_area( ref, t1,
wincr.left, wincr.top, wincr.width, wincr.height ) ||
im_extract_area( sec, t2,
srhcr.left, srhcr.top, srhcr.width, srhcr.height ) ) {
im_close( surface );
return( -1 );
}
/* Make sure we have just one band. From im_*mosaic() we will, but
* from im_match_linear_search() etc. we may not.
*/
if( t1->Bands != 1 ) {
if( im_extract_band( t1, t3, 0 ) ) {
im_close( surface );
return( -1 );
}
t1 = t3;
}
if( t2->Bands != 1 ) {
if( im_extract_band( t2, t4, 0 ) ) {
im_close( surface );
return( -1 );
}
t2 = t4;
}
/* Search!
*/
if( im_spcor( t2, t1, surface ) ) {
im_close( surface );
return( -1 );
}
/* Find maximum of correlation surface.
*/
if( im_maxpos( surface, x, y, correlation ) ) {
im_close( surface );
return( -1 );
}
im_close( surface );
/* Translate back to position within sec.
*/
*x += srhcr.left;
*y += srhcr.top;
return( 0 );
}
int
im__chkpair( IMAGE *ref, IMAGE *sec, TIE_POINTS *points )
{
int i;
int x, y;
double correlation;
const int hcor = points->halfcorsize;
const int harea = points->halfareasize;
/* Check images.
*/
if( im_incheck( ref ) || im_incheck( sec ) )
return( -1 );
if( ref->Bands != sec->Bands || ref->BandFmt != sec->BandFmt ||
ref->Coding != sec->Coding ) {
im_errormsg( "im_chkpair: inputs incompatible");
return( -1 );
}
if( ref->Bands != 1 || ref->BandFmt != IM_BANDFMT_UCHAR ) {
im_errormsg( "im_chkpair: help!" );
return( -1 );
}
for( i = 0; i < points->nopoints; i++ ) {
/* Find correlation point.
*/
if( im_correl( ref, sec,
points->x_reference[i], points->y_reference[i],
points->x_reference[i], points->y_reference[i],
hcor, harea,
&correlation, &x, &y ) )
return( -1 );
/* And note in x_secondary.
*/
points->x_secondary[i] = x;
points->y_secondary[i] = y;
points->correlation[i] = correlation;
/* Note each dx, dy too.
*/
points->dx[i] =
points->x_secondary[i] - points->x_reference[i];
points->dy[i] =
points->y_secondary[i] - points->y_reference[i];
}
return( 0 );
}