libvips/libsrc/convolution/im_resize_linear.c

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2007-08-29 18:23:50 +02:00
/* im_lowpass()
* History:
* 27/10/94 JC
* - IM_ARRAY modified to use local allocation
* - im_iscomplex() call added
* 17/2/95 JC
* - modernised a little
* 18/8/95 JC
* - name changed to reflect function more closely
* 2/6/04
* - was detecting edges incorrectly, segv for some images (thanks Javi)
*/
/*
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*/
/* What we do for each pel.
*/
#define LOOP( TYPE ) \
if( Xint >= 0 && Yint >=0 && \
Xint < in->Xsize-1 && Yint < in->Ysize-1 ) \
for( bb = 0; bb < in->Bands; bb++ ) { \
TYPE s1 = *((TYPE *) p); \
TYPE s2 = *((TYPE *) (p + ips)); \
TYPE s3 = *((TYPE *) (p + ils)); \
TYPE s4 = *((TYPE *) (p + ips + ils)); \
TYPE *t = (TYPE *) q; \
\
*t = (1-dx)*(1-dy)*s1 + dx*(1-dy)*s2 + \
dy*(1-dx)*s3 + dx*dy*s4; \
\
p += ies; \
q += oes; \
} \
else if( Xint == in->Xsize-1 && Yint >= 0 && Yint < in->Ysize - 1 ) \
for( bb = 0; bb < in->Bands; bb++ ) { \
TYPE s1 = *((TYPE *) p); \
TYPE s3 = *((TYPE *) (p + ils)); \
TYPE *t = (TYPE *) q; \
\
*t = (1-dy)*s1 + dy*s3; \
\
p += ies; \
q += oes; \
} \
else if( Yint == in->Ysize-1 && Xint >= 0 && Xint < in->Xsize - 1 ) \
for( bb = 0; bb < in->Bands; bb++ ) { \
TYPE s1 = *((TYPE *) p); \
TYPE s2 = *((TYPE *) (p + ips)); \
TYPE *t = (TYPE *) q; \
\
*t = (1-dx)*s1 + dx*s2; \
\
p += ies; \
q += oes; \
} \
else \
for( bb = 0; bb < in->Bands; bb++ ) { \
unsigned char s1 = *((unsigned char *) p); \
TYPE *t = (TYPE *) q; \
\
*t = s1; \
\
p += ies; \
q += oes; \
}
int
im_resize_linear( IMAGE *in, IMAGE *out, int X, int Y )
{
double dx, dy, xscale, yscale;
double Xnew, Ynew; /* inv. coord. of the interpolated pt */
int x, y;
int Xint, Yint;
int bb;
PEL *input, *opline;
PEL *q, *p;
int ils, ips, ies; /* Input and output line, pel and */
int ols, ops, oes; /* element sizes */
if( im_iocheck( in, out ) )
return( -1 );
if( im_iscomplex( in ) ) {
im_errormsg( "im_lowpass: non-complex input only" );
return( -1 );
}
if( in->Coding != IM_CODING_NONE ) {
im_errormsg("im_lowpass: input should be uncoded");
return( -1 );
}
if( im_cp_desc( out, in ) )
return( -1 );
out->Xsize = X;
out->Ysize = Y;
if( im_setupout( out ) )
return( -1 );
ils = IM_IMAGE_SIZEOF_LINE( in );
ips = IM_IMAGE_SIZEOF_PEL( in );
ies = IM_IMAGE_SIZEOF_ELEMENT( in );
ols = IM_IMAGE_SIZEOF_LINE( out );
ops = IM_IMAGE_SIZEOF_PEL( out );
oes = IM_IMAGE_SIZEOF_ELEMENT( out );
/* buffer lines
***************/
if( !(opline = IM_ARRAY( out, ols, PEL )) )
return( -1 );
/* Resampling
*************/
input = (PEL*) in->data;
xscale = ((double)in->Xsize-1)/(X-1);
yscale = ((double)in->Ysize-1)/(Y-1);
for (y=0; y<Y; y++)
{
q = opline;
for (x=0; x<X; x++)
{
Xnew = x*xscale;
Ynew = y*yscale;
Xint = floor(Xnew);
Yint = floor(Ynew);
dx = Xnew - Xint;
dy = Ynew - Yint;
p = input + Xint*ips + Yint*ils;
switch( in->BandFmt ) {
case IM_BANDFMT_UCHAR: LOOP( unsigned char); break;
case IM_BANDFMT_USHORT: LOOP( unsigned short ); break;
case IM_BANDFMT_UINT: LOOP( unsigned int ); break;
case IM_BANDFMT_CHAR: LOOP( signed char ); break;
case IM_BANDFMT_SHORT: LOOP( signed short ); break;
case IM_BANDFMT_INT: LOOP( signed int ); break;
case IM_BANDFMT_FLOAT: LOOP( float ); break;
case IM_BANDFMT_DOUBLE: LOOP( double ); break;
default:
im_errormsg( "im_lowpass: unsupported image type" );
return( -1 );
/*NOTREACHED*/
}
}
if (im_writeline(y, out, opline) )
return(-1);
}
return(0);
}