99 lines
2.3 KiB
C
99 lines
2.3 KiB
C
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/* @(#) Scale an image so that min(im) maps to 0 and max(im) maps to 255. If
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* @(#) min(im)==max(im), then we return black. Any non-complex type.
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* @(#)
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* @(#) int
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* @(#) im_scale( in, out )
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* @(#) IMAGE *in, *out;
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* @(#)
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* @(#) Returns 0 on success and -1 on error
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* @(#)
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*
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* Author: John Cupitt
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* Written on: 22/4/93
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* Modified on:
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* 30/6/93 JC
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* - adapted for partial v2
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* - ANSI
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* 31/8/93 JC
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* - calculation of offset now includes scale
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* 8/5/06
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* - set Type on output too
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* 16/10/06
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* - what? no, don't set Type, useful to be able to scale histograms, for
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* example
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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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#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 <stdio.h>
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#include <stdlib.h>
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#include <vips/vips.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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/* Scale, as noted above.
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*/
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int
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im_scale( IMAGE *in, IMAGE *out )
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{
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DOUBLEMASK *stats;
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IMAGE *t = im_open_local( out, "im_scale:1", "p" );
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double mx, mn;
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double scale, offset;
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/* Measure min and max, calculate transform.
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*/
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if( !t || !(stats = im_stats( in )) )
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return( -1 );
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mn = stats->coeff[0];
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mx = stats->coeff[1];
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im_free_dmask( stats );
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if( mn == mx )
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/* Range of zero: just return black.
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*/
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return( im_black( out, in->Xsize, in->Ysize, in->Bands ) );
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scale = 255.0 / (mx - mn);
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offset = -(mn * scale);
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/* Transform!
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*/
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if( im_lintra( scale, in, offset, t ) ||
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im_clip( t, out ) )
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return( -1 );
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return( 0 );
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}
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