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/* im_scale
*
* Author: John Cupitt
* Written on: 22/4/93
* Modified on:
* 30/6/93 JC
* - adapted for partial v2
* - ANSI
* 31/8/93 JC
* - calculation of offset now includes scale
* 8/5/06
* - set Type on output too
* 16/10/06
* - what? no, don't set Type, useful to be able to scale histograms, for
* example
* 1/2/10
* - gtkdoc
*/
/*
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 <vips/vips.h>
/**
* im_scale:
* @in: input image
* @out: output image
*
* Search the image for the maximum and minimum value, then return the image
* as unsigned 8-bit, scaled so that the maximum value is 255 and the
* minimum is zero.
*
* See also: im_clip2fmt(), im_scaleps().
*
* Returns: 0 on success, -1 on error
*/
int
im_scale( IMAGE *in, IMAGE *out )
{
DOUBLEMASK *stats;
IMAGE *t = im_open_local( out, "im_scale:1", "p" );
double mx, mn;
double scale, offset;
/* Measure min and max, calculate transform.
*/
if( !t || !(stats = im_stats( in )) )
return( -1 );
mn = VIPS_MASK( stats, 0, 0 );
mx = VIPS_MASK( stats, 1, 0 );
im_free_dmask( stats );
if( mn == mx )
/* Range of zero: just return black.
*/
return( im_black( out, in->Xsize, in->Ysize, in->Bands ) );
scale = 255.0 / (mx - mn);
offset = -(mn * scale);
/* Transform!
*/
if( im_lintra( scale, in, offset, t ) ||
im_clip2fmt( t, out, IM_BANDFMT_UCHAR ) )
return( -1 );
return( 0 );
}
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