121 lines
2.9 KiB
C
121 lines
2.9 KiB
C
/* im_point_bilinear.c
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*
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* Copyright: 2006, The Nottingham Trent University
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*
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* Author: Tom Vajzovic
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*
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* Written on: 2006-09-26
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*
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* 9/9/09
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* - rewrite in terms of im_affinei() and im_avg()
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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., 51 Franklin Street, Fifth Floor, Boston, MA
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02110-1301 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 <glib/gi18n-lib.h>
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#include <math.h>
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#include <vips/vips.h>
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#include <vips/vips7compat.h>
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/**
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* im_point:
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* @im: image to read from
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* @interpolate: interpolator to sample points with
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* @x: x position to interpolate
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* @y: y position to interpolate
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* @band: band to read
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* @out: return interpolated value
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*
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* Find the value at (@x, @y) in given band of image.
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* Non-integral values are calculated using the supplied @interpolate.
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*
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* See also: im_avg(), #VipsInterpolate
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*
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* Returns: 0 on success, -1 on error
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*/
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int
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im_point( IMAGE *im, VipsInterpolate *interpolate,
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double x, double y, int band, double *out )
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{
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IMAGE *mem;
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IMAGE *t[2];
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if( band >= im->Bands ||
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x < 0.0 || y < 0.0 ||
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x > im->Xsize || y > im->Ysize ) {
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im_error( "im_point_bilinear", "%s",
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_( "coords outside image" ) );
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return( -1 );
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}
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if( !(mem = im_open( "im_point", "p" )) )
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return( -1 );
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if( im_open_local_array( mem, t, 2, "im_point", "p" ) ||
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im_extract_band( im, t[0], band ) ||
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im_affinei( t[0], t[1],
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interpolate,
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1, 0, 0, 1,
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floor( x ) - x, floor( y ) - y,
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floor( x ), floor( y ), 1, 1 ) ||
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im_avg( t[1], out ) ) {
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im_close( mem );
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return( -1 );
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}
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im_close( mem );
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return( 0 );
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}
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/**
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* im_point_bilinear:
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* @im: image to read from
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* @x: x position to interpolate
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* @y: y position to interpolate
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* @band: band to read
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* @out: return interpolated value
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*
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* Find the value at (@x,@y) in given band of image.
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* Use bilinear interpolation if @x or @y are non-integral.
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*
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* See also: im_avg(), im_point().
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*
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* Returns: 0 on success, -1 on error
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*/
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int
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im_point_bilinear( IMAGE *im, double x, double y, int band, double *out )
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{
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return( im_point( im, vips_interpolate_bilinear_static(),
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x, y, band, out ) );
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}
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