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/* im_point_bilinear.c
*
* Copyright: 2006, The Nottingham Trent University
*
* Author: Tom Vajzovic
*
* Written on: 2006-09-26
*
* 9/9/09
* - rewrite in terms of im_affinei() and im_avg()
*/
/*
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., 51 Franklin Street, Fifth Floor, Boston, MA
02110-1301 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 <math.h>
#include <vips/vips.h>
/**
* im_point:
* @im: image to read from
* @interpolate: interpolator to sample points with
* @x: x position to interpolate
* @y: y position to interpolate
* @band: band to read
* @out: return interpolated value
*
* Find the value at (@x, @y) in given band of image.
* Non-integral values are calculated using the supplied @interpolate.
*
* See also: im_avg(), #VipsInterpolate
*
* Returns: 0 on success, -1 on error
*/
int
im_point( IMAGE *im, VipsInterpolate *interpolate,
double x, double y, int band, double *out )
{
IMAGE *mem;
IMAGE *t[2];
if( band >= im->Bands ||
x < 0.0 || y < 0.0 ||
x > im->Xsize || y > im->Ysize ) {
im_error( "im_point_bilinear", "%s",
_( "coords outside image" ) );
return( -1 );
}
if( !(mem = im_open( "im_point", "p" )) )
return( -1 );
if( im_open_local_array( mem, t, 2, "im_point", "p" ) ||
im_extract_band( im, t[0], band ) ||
im_affinei( t[0], t[1],
interpolate,
1, 0, 0, 1,
floor( x ) - x, floor( y ) - y,
floor( x ), floor( y ), 1, 1 ) ||
im_avg( t[1], out ) ) {
im_close( mem );
return( -1 );
}
im_close( mem );
return( 0 );
}
/**
* im_point_bilinear:
* @im: image to read from
* @x: x position to interpolate
* @y: y position to interpolate
* @band: band to read
* @out: return interpolated value
*
* Find the value at (@x,@y) in given band of image.
* Use bilinear interpolation if @x or @y are non-integral.
*
* See also: im_avg(), im_point().
*
* Returns: 0 on success, -1 on error
*/
int
im_point_bilinear( IMAGE *im, double x, double y, int band, double *out )
{
return( im_point( im, vips_interpolate_bilinear_static(),
x, y, band, out ) );
}
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