libvips/libsrc/arithmetic/im_bandmean.c

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2007-08-29 18:23:50 +02:00
/* @(#) Average the bands in an image.
* @(#)
* @(#) int
* @(#) im_bandmean(in, out)
* @(#) IMAGE *in, *out;
* @(#)
* @(#) Returns 0 on success and -1 on error
*
* Author: Simon Goodall
* Written on: 17/7/07
* 17/7/07 JC
* - hacked about a bit
*/
/*
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 <assert.h>
#include <vips/vips.h>
#include <vips/internal.h>
#ifdef WITH_DMALLOC
#include <dmalloc.h>
#endif /*WITH_DMALLOC*/
/* Int types. Round, keep sum in a larger variable.
*/
#define ILOOP( TYPE, STYPE ) { \
TYPE *p1 = (TYPE *) p; \
TYPE *q1 = (TYPE *) q; \
\
for( i = 0; i < n; i++ ) { \
STYPE sum; \
\
sum = 0; \
for( j = 0; j < b; j++ ) \
sum += p1[j]; \
*q1++ = sum > 0 ? (sum + b / 2) / b : (sum - b / 2) / b; \
p1 += b; \
} \
}
/* Float loop. No rounding, sum in same container.
*/
#define FLOOP( TYPE ) { \
TYPE *p1 = (TYPE *) p; \
TYPE *q1 = (TYPE *) q; \
\
for( i = 0; i < n; i++ ) { \
TYPE sum; \
\
sum = 0; \
for( j = 0; j < b; j++ ) \
sum += p1[j]; \
*q1++ = sum / b; \
p1 += b; \
} \
}
/* Complex loop. Mean reals and imaginaries separately.
*/
#define CLOOP( TYPE ) { \
TYPE *p1 = (TYPE *) p; \
TYPE *q1 = (TYPE *) q; \
\
for( i = 0; i < n * 2; i += 2 ) { \
TYPE sum; \
\
sum = 0; \
for( j = 0; j < b; j++ ) \
sum += p1[j * 2]; \
q1[0] = sum / b; \
sum = 0; \
for( j = 0; j < b; j++ ) \
sum += p1[j * 2 + 1]; \
q1[1] = sum / b; \
p1 += b; \
q1 += 2; \
} \
}
static void
bandmean_buffer( PEL *p, PEL *q, int n, IMAGE *in )
{
int i, j;
const int b = in->Bands;
switch( in->BandFmt ) {
case IM_BANDFMT_CHAR: ILOOP( signed char, int ); break;
case IM_BANDFMT_UCHAR: ILOOP( unsigned char, unsigned int ); break;
case IM_BANDFMT_SHORT: ILOOP( signed short, int ); break;
case IM_BANDFMT_USHORT: ILOOP( unsigned short, unsigned int ); break;
case IM_BANDFMT_INT: ILOOP( signed int, int ); break;
case IM_BANDFMT_UINT: ILOOP( unsigned int, unsigned int ); break;
case IM_BANDFMT_FLOAT: FLOOP( float ); break;
case IM_BANDFMT_DOUBLE: FLOOP( double ); break;
case IM_BANDFMT_COMPLEX: CLOOP( float ); break;
case IM_BANDFMT_DPCOMPLEX: CLOOP( double ); break;
default:
assert( 0 );
}
}
int
im_bandmean( IMAGE *in, IMAGE *out )
{
/* Check input params
*/
if( in->Bands == 1 )
return( im_copy( in, out ) );
if( in->Coding != IM_CODING_NONE ) {
im_error( "im_bandmean", _( "uncoded multiband only" ) );
return( -1 );
}
/* Prepare output image.
*/
if( im_cp_desc( out, in ) )
return( -1 );
out->Bands = 1;
out->Type = IM_TYPE_B_W;
/* And process!
*/
if( im_wrapone( in, out,
(im_wrapone_fn) bandmean_buffer, in, NULL ) )
return( -1 );
return( 0 );
}