libvips/libsrc/histograms_lut/im_stdif.c

263 lines
6.2 KiB
C

/* @(#) Functions which calculates statistical differenciating according to
* @(#) the formula given in page 45 of the book "An intro to digital image
* @(#) processing" by Wayne Niblack
* @(#)
* @(#) At point (i,j) the output is given by the eqn:
* @(#)
* @(#) vout(i,j) = a*m0 +(1-a)*meanv +
* @(#) (vin(i,j) - meanv) * beta*sigma0/(sigma0+beta*stdv)
* @(#)
* @(#) Values a, m0, beta and sigma0 are entered
* @(#) meanv and stdv are the values calculated over a moving window
* @(#) xwin and ywin are the sizes of the used window
* @(#) The resultant coefficients are written as floats
* @(#) in out which has a size of in
* @(#)
* @(#) int im_stdif(in, im, alpha, mean0, beta, sigma0, xwin, ywin)
* @(#) IMAGE *in, *out;
* @(#) int xwin, ywin;
* @(#) double alpha, mean0, beta, sigma0;
* @(#)
* @(#) Returns 0 on sucess and -1 on error.
*
* Copyright: 1990, N. Dessipris.
*
* Author: Nicos Dessipris
* Written on: 02/05/1990
* Modified on :
* 6/8/93 JC
* - now works for odd window sizes
* - ANSIfication
* 25/5/95 JC
* - new IM_ARRAY() macro
* 25/1/96 JC
* - im_lhisteq() adapted to make new im_stdif()
* - now partial, plus rolling window
* - 5x faster, amazingly
* - works
* 7/4/04
* - now uses im_embed() with edge stretching on the input, not
* the output
*/
/*
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>
#ifdef WITH_DMALLOC
#include <dmalloc.h>
#endif /*WITH_DMALLOC*/
/* Hold global stuff here.
*/
typedef struct {
int xwin, ywin; /* Parameters */
double a, m0, b, s0;
} StdifInfo;
/* stdif generate function.
*/
static int
stdif_gen( REGION *or, void *seq, void *a, void *b )
{
REGION *ir = (REGION *) seq;
StdifInfo *inf = (StdifInfo *) b;
Rect irect;
Rect *r = &or->valid;
int le = r->left;
int to = r->top;
int bo = IM_RECT_BOTTOM(r);
int ri = IM_RECT_RIGHT(r);
int x, y, i, j;
int lsk;
int coff; /* Offset to move to centre of window */
int npel = inf->xwin * inf->ywin;
/* What part of ir do we need?
*/
irect.left = or->valid.left;
irect.top = or->valid.top;
irect.width = or->valid.width + inf->xwin;
irect.height = or->valid.height + inf->ywin;
if( im_prepare( ir, &irect ) )
return( -1 );
lsk = IM_REGION_LSKIP( ir );
coff = lsk * (inf->ywin/2) + inf->xwin/2;
for( y = to; y < bo; y++ ) {
/* Get input and output pointers for this line.
*/
PEL *p = (PEL *) IM_REGION_ADDR( ir, le, y );
PEL *q = (PEL *) IM_REGION_ADDR( or, le, y );
PEL *p1, *p2;
int sum = 0;
int sum2 = 0;
/* Precompute some factors.
*/
double f1 = inf->a * inf->m0;
double f2 = 1.0 - inf->a;
double f3 = inf->b * inf->s0;
/* Find sum, sum of squares for the start of this line.
*/
for( p1 = p, j = 0; j < inf->ywin; j++, p1 += lsk )
for( p2 = p1, i = 0; i < inf->xwin; i++, p2++ ) {
int t = *p2;
sum += t;
sum2 += t * t;
}
/* Loop for output pels.
*/
for( x = le; x < ri; x++, p++ ) {
/* Find stats.
*/
double mean = (double)sum / npel;
double var = (double)sum2 / npel - (mean * mean);
double sig = sqrt( var );
/* Transform.
*/
double res = f1 + f2*mean + ((double) p[coff] - mean) *
(f3 / (inf->s0 + inf->b*sig));
/* And write.
*/
if( res < 0.0 )
*q++ = 0;
else if( res >= 256.0 )
*q++ = 255;
else
*q++ = res + 0.5;
/* Adapt sums - remove the pels from the left hand
* column, add in pels for a new right-hand column.
*/
for( p1 = p, j = 0; j < inf->ywin; j++, p1 += lsk ) {
int t1 = p1[0];
int t2 = p1[inf->xwin];
sum -= t1;
sum2 -= t1 * t1;
sum += t2;
sum2 += t2 * t2;
}
}
}
return( 0 );
}
int
im_stdif_raw( IMAGE *in, IMAGE *out,
double a, double m0, double b, double s0,
int xwin, int ywin )
{
StdifInfo *inf;
if( m0 < 0 || m0 > 255 || a < 0 || a > 1.0 || b < 0 || b > 2 ||
s0 < 0 || s0 > 255 ) {
im_errormsg( "im_stdif: parameters out of range" );
return( -1 );
}
if( im_piocheck( in, out ) )
return( -1 );
if( in->Bbits != IM_BBITS_BYTE || in->BandFmt != IM_BANDFMT_UCHAR ||
in->Bands != 1 || in->Coding != IM_CODING_NONE ) {
im_errormsg( "im_stdif: one band uchar uncoded only" );
return( -1 );
}
if( xwin > in->Xsize || ywin > in->Ysize ) {
im_errormsg( "im_stdif: window too large" );
return( -1 );
}
if( im_cp_desc( out, in ) )
return( -1 );
out->Xsize -= xwin;
out->Ysize -= ywin;
/* Save parameters.
*/
if( !(inf = IM_NEW( out, StdifInfo )) )
return( -1 );
inf->xwin = xwin;
inf->ywin = ywin;
inf->a = a;
inf->m0 = m0;
inf->b = b;
inf->s0 = s0;
/* Set demand hints. FATSTRIP is good for us, as THINSTRIP will cause
* too many recalculations on overlaps.
*/
if( im_demand_hint( out, IM_FATSTRIP, in, NULL ) )
return( -1 );
/* Write the hist.
*/
if( im_generate( out,
im_start_one, stdif_gen, im_stop_one, in, inf ) )
return( -1 );
return( 0 );
}
/* The above, with a border to make out the same size as in.
*/
int
im_stdif( IMAGE *in, IMAGE *out,
double a, double m0, double b, double s0,
int xwin, int ywin )
{
IMAGE *t1 = im_open_local( out, "im_stdif:1", "p" );
if( !t1 ||
im_embed( in, t1, 1, xwin / 2, ywin / 2,
in->Xsize + xwin - 1,
in->Ysize + ywin - 1 ) ||
im_stdif_raw( t1, out, a, m0, b, s0, xwin, ywin ) )
return( -1 );
return( 0 );
}