331 lines
7.8 KiB
C
331 lines
7.8 KiB
C
/* @(#) Functions which calculates the correlation coefficient between two
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* @(#) images.
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* @(#)
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* @(#) int im_spcor( IMAGE *in, IMAGE *ref, IMAGE *out )
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* @(#)
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* @(#) We calculate:
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* @(#)
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* @(#) sumij (ref(i,j)-mean(ref))(inkl(i,j)-mean(inkl))
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* @(#) c(k,l) = ------------------------------------------------
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* @(#) sqrt(sumij (ref(i,j)-mean(ref))^2) *
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* @(#) sqrt(sumij (inkl(i,j)-mean(inkl))^2)
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* @(#)
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* @(#) where inkl is the area of in centred at position (k,l).
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* @(#)
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* @(#) Writes float to out. in and ref must be 1 band uchar, or 1 band
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* @(#) ushort.
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* @(#)
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* @(#) Returns 0 on sucess and -1 on error.
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*
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* Copyright: 1990, N. Dessipris; 2006, 2007 Nottingham Trent University.
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*
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*
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* Author: Nicos Dessipris
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* Written on: 02/05/1990
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* Modified on :
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* 20/2/95 JC
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* - updated
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* - ANSIfied, a little
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* 21/2/95 JC
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* - rewritten
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* - partialed
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* - speed-ups
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* - new correlation coefficient (see above), from Niblack "An
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* Introduction to Digital Image Processing", Prentice/Hall, pp 138.
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* 4/9/97 JC
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* - now does short/ushort as well
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* 13/2/03 JC
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* - oops, could segv for short images
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* 14/4/04 JC
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* - sets Xoffset / Yoffset
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* 8/3/06 JC
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* - use im_embed() with edge stretching on the input, not the output
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*
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* 2006-10-24 tcv
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* - add im_spcor2
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*
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* 2007-11-12 tcv
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* - make im_spcor a wrapper selecting either im__spcor or im__spcor2
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* 2008-09-09 JC
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* - roll back the windowed version for now, it has some tile edge effects
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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 <stdlib.h>
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#include <string.h>
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#include <stdio.h>
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#include <math.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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/* Hold per-call state here.
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*/
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typedef struct {
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IMAGE *ref; /* Image we are searching for */
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double rmean; /* Mean of search window */
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double c1; /* sqrt(sumij (ref(i,j)-mean(ref))^2) */
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} Spcor;
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#define LOOP(IN) { \
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IN *a = (IN *) p; \
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IN *b = (IN *) ref->data; \
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int in_lsk = lsk / sizeof( IN ); \
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IN *a1, *b1; \
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\
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/* For each pel in or, loop over ref. First, \
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* calculate mean of area in ir corresponding to ref. \
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*/ \
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for( a1 = a, sum1 = 0, j = 0; j < ref->Ysize; j++, a1 += in_lsk ) \
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for( i = 0; i < ref->Xsize; i++ ) \
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sum1 += a1[i]; \
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imean = (double) sum1 / (ref->Xsize * ref->Ysize); \
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\
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/* Loop over ir again, this time calculating \
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* sum-of-squares-of-differences for this window on \
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* ir, and also sum-of-products-of-differences from mean. \
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*/ \
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for( a1 = a, b1 = b, sum2 = 0.0, sum3 = 0.0, j = 0; \
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j < ref->Ysize; j++, a1 += in_lsk, b1 += ref->Xsize ) { \
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for( i = 0; i < ref->Xsize; i++ ) { \
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/* Reference pel, and input pel. \
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*/ \
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IN rp = b1[i]; \
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IN ip = a1[i]; \
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\
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/* Accumulate sum-of-squares-of- \
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* differences for input image. \
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*/ \
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double t = ip - imean; \
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sum2 += t * t; \
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\
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/* Accumulate product-of-difference from mean. \
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*/ \
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sum3 += (rp - spcor->rmean) * (ip - imean); \
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} \
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} \
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}
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/* spcor generate function.
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*/
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static int
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spcor_gen( REGION *or, void *vseq, void *a, void *b )
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{
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REGION *ir = (REGION *) vseq;
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Spcor *spcor = (Spcor *) b;
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IMAGE *ref = spcor->ref;
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Rect irect;
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Rect *r = &or->valid;
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int le = r->left;
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int to = r->top;
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int bo = IM_RECT_BOTTOM(r);
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int ri = IM_RECT_RIGHT(r);
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int x, y, i, j;
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int lsk;
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double imean;
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double sum1;
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double sum2, sum3;
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double c2, cc;
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/* What part of ir do we need?
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*/
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irect.left = or->valid.left;
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irect.top = or->valid.top;
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irect.width = or->valid.width + ref->Xsize - 1;
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irect.height = or->valid.height + ref->Ysize - 1;
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if( im_prepare( ir, &irect ) )
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return( -1 );
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lsk = IM_REGION_LSKIP( ir );
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/* Loop over or.
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*/
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for( y = to; y < bo; y++ ) {
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float *q = (float *) IM_REGION_ADDR( or, le, y );
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for( x = le; x < ri; x++ ) {
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PEL *p = (PEL *) IM_REGION_ADDR( ir, x, y );
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/* Find sums for this position.
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*/
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switch( ref->BandFmt ) {
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case IM_BANDFMT_UCHAR: LOOP(unsigned 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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default:
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error_exit( "im_spcor: internal error #7934" );
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/* Keep gcc -Wall happy.
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*/
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return( -1 );
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}
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/* Now: calculate correlation coefficient!
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*/
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c2 = sqrt( sum2 );
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cc = sum3 / (spcor->c1 * c2);
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*q++ = cc;
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}
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}
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return( 0 );
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}
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/* Pre-calculate stuff for our reference image.
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*/
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static Spcor *
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spcor_new( IMAGE *out, IMAGE *ref )
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{
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Spcor *spcor;
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int sz = ref->Xsize * ref->Ysize;
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PEL *p = (PEL *) ref->data;
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double s;
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int i;
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if( !(spcor = IM_NEW( out, Spcor )) )
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return( NULL );
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/* Pre-calculate stuff on our reference image.
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*/
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spcor->ref = ref;
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if( im_avg( spcor->ref, &spcor->rmean ) )
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return( NULL );
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/* Find sqrt-of-sum-of-squares-of-differences.
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*/
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for( s = 0.0, i = 0; i < sz; i++ ) {
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double t = (int) p[i] - spcor->rmean;
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s += t * t;
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}
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spcor->c1 = sqrt( s );
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return( spcor );
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}
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int
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im_spcor_raw( IMAGE *in, IMAGE *ref, IMAGE *out )
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{
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Spcor *spcor;
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/* PIO between in and out; WIO from ref, since it's probably tiny.
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*/
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if( im_piocheck( in, out ) ||
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im_incheck( ref ) )
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return( -1 );
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/* Check sizes.
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*/
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if( in->Xsize < ref->Xsize ||
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in->Ysize < ref->Ysize ) {
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im_error( "im_spcor_raw", _( "ref not smaller than in" ) );
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return( -1 );
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}
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/* Check types.
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*/
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if( in->Coding != IM_CODING_NONE ||
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in->Bands != 1 ||
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ref->Coding != IM_CODING_NONE ||
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ref->Bands != 1 ||
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in->BandFmt != ref->BandFmt ) {
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im_error( "im_spcor_raw", _( "input not uncoded 1 band" ) );
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return( -1 );
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}
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if( in->BandFmt != IM_BANDFMT_UCHAR &&
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in->BandFmt != IM_BANDFMT_CHAR &&
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in->BandFmt != IM_BANDFMT_SHORT &&
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in->BandFmt != IM_BANDFMT_USHORT ) {
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im_error( "im_spcor_raw", _( "input not char/uchar/short/ushort" ) );
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return( -1 );
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}
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/* Prepare the output image.
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*/
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if( im_cp_descv( out, in, ref, NULL ) )
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return( -1 );
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out->Bbits = IM_BBITS_FLOAT;
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out->BandFmt = IM_BANDFMT_FLOAT;
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out->Xsize = in->Xsize - ref->Xsize + 1;
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out->Ysize = in->Ysize - ref->Ysize + 1;
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/* Pre-calculate some stuff.
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*/
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if( !(spcor = spcor_new( out, ref )) )
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return( -1 );
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/* Set demand hints. FATSTRIP is good for us, as THINSTRIP will cause
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* too many recalculations on overlaps.
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*/
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if( im_demand_hint( out, IM_FATSTRIP, in, NULL ) )
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return( -1 );
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/* Write the correlation.
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*/
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if( im_generate( out,
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im_start_one, spcor_gen, im_stop_one, in, spcor ) )
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return( -1 );
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out->Xoffset = -ref->Xsize / 2;
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out->Yoffset = -ref->Ysize / 2;
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return( 0 );
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}
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/* The above, with the input expanded to make out the same size as in.
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*/
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int
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im_spcor( IMAGE *in, IMAGE *ref, IMAGE *out )
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{
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IMAGE *t1 = im_open_local( out, "im_spcor intermediate", "p" );
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if( !t1 ||
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im_embed( in, t1, 1,
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ref->Xsize / 2, ref->Ysize / 2,
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in->Xsize + ref->Xsize - 1,
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in->Ysize + ref->Ysize - 1 ) ||
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im_spcor_raw( t1, ref, out ) )
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return( -1 );
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out->Xoffset = 0;
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out->Yoffset = 0;
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return( 0 );
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}
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