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/* im_scaleps
*
* Copyright: 1990, N. Dessipris.
*
* Author: Nicos Dessipris
* Written on: 02/05/1990
* Modified on: 14/03/1991
* 15/6/93 J.Cupitt
* - externs fixed
* - includes fixed
* 13/2/95 JC
* - ANSIfied
* - cleaned up
* 11/7/02 JC
* - rewritten ... got rid of the stuff for handling -ves, never used
* (and was broken anyway)
* 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 <math.h>
#include <vips/vips.h>
/**
* im_scaleps:
* @in: input image
* @out: output image
*
* Scale a power spectrum. Transform with log10(1.0 + pow(x, 0.25)) + .5,
* then scale so max == 255.
*
* See also: im_scale().
*
* Returns: 0 on success, -1 on error
*/
int
im_scaleps( IMAGE *in, IMAGE *out )
{
IMAGE *t[4];
double mx;
double scale;
if( im_open_local_array( out, t, 4, "im_scaleps-1", "p" ) ||
im_max( in, &mx ) )
return( -1 );
if( mx <= 0.0 )
/* Range of zero: just return black.
*/
return( im_black( out, in->Xsize, in->Ysize, in->Bands ) );
scale = 255.0 / log10( 1.0 + pow( mx, .25 ) );
/* Transform!
*/
if( im_powtra( in, t[0], 0.25 ) ||
im_lintra( 1.0, t[0], 1.0, t[1] ) ||
im_log10tra( t[1], t[2] ) ||
im_lintra( scale, t[2], 0.0, t[3] ) ||
im_clip2fmt( t[3], out, IM_BANDFMT_UCHAR ) )
return( -1 );
return( 0 );
}
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