128 lines
3.5 KiB
C
128 lines
3.5 KiB
C
/* @(#) 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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* @(#) int im_maxpos_vec(
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* @(#) IMAGE *im,
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* @(#) double x,
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* @(#) double y,
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* @(#) int band,
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* @(#) double *val
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* @(#) );
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* @(#)
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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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/*
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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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 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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/** HEADERS **/
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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 <vips/intl.h>
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#include <vips/vips.h>
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#include <vips/r_access.h>
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#ifdef WITH_DMALLOC
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#include <dmalloc.h>
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#endif /*WITH_DMALLOC */
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/** EXPORTED FUNCTION **/
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int im_point_bilinear( IMAGE *im, double x, double y, int band, double *val ){
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#define FUNCTION_NAME "im_point_bilinear"
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double x_frac= x - (int) x;
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double y_frac= y - (int) y;
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Rect need= { x, y, ( x_frac ? 2 : 1 ), ( y_frac ? 2 : 1 ) };
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REGION *reg;
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if( im_pincheck( im ) )
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return -1;
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if( im-> Coding ){
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im_error( FUNCTION_NAME, "%s", _("uncoded images only") );
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return -1;
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}
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if( !( im_isint( im ) || im_isfloat( im ) ) ){
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im_error( FUNCTION_NAME, "%s", _("scalar images only") );
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return -1;
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}
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if( band >= im-> Bands || x < 0.0 || y < 0.0 || x > im-> Xsize || y > im-> Ysize ){
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im_error( FUNCTION_NAME, "%s", _("coords outside image") );
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return -1;
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}
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if( ! val ){
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im_error( FUNCTION_NAME, "%s", _("invalid arguments") );
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return -1;
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}
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reg= im_region_create( im );
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if( ! reg || im_prepare( reg, &need ) )
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return -1;
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if( ! im_rect_includesrect( ®-> valid, &need ) ){
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im_error( FUNCTION_NAME, "%s", _("coords outside image") );
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im_region_free( reg );
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return -1;
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}
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if( x_frac )
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if( y_frac )
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*val= x_frac * y_frac * (double) IM_REGION_VALUE( reg, ((int)x + 1), ((int)y + 1), band )
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+ x_frac * ( 1.0 - y_frac ) * (double) IM_REGION_VALUE( reg, ((int)x + 1), (int)y , band )
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+ ( 1.0 - x_frac ) * y_frac * (double) IM_REGION_VALUE( reg, (int)x, ((int)y + 1), band )
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+ ( 1.0 - x_frac ) * ( 1.0 - y_frac ) * (double) IM_REGION_VALUE( reg, (int)x, (int)y , band );
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else
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*val= x_frac * IM_REGION_VALUE( reg, ((int)x + 1), (int)y, band )
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+ ( 1.0 - x_frac ) * IM_REGION_VALUE( reg, (int)x, (int)y, band );
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else
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if( y_frac )
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*val= y_frac * IM_REGION_VALUE( reg, (int)x, ((int)y + 1), band )
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+ ( 1.0 - y_frac ) * IM_REGION_VALUE( reg, (int)x, (int)y , band );
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else
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*val= IM_REGION_VALUE( reg, (int)x, (int)y, band );
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im_region_free( reg );
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return 0;
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#undef FUNCTION_NAME
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}
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