100 lines
2.2 KiB
C
100 lines
2.2 KiB
C
/* im_scaleps
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*
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* Copyright: 1990, N. Dessipris.
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*
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* Author: Nicos Dessipris
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* Written on: 02/05/1990
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* Modified on: 14/03/1991
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* 15/6/93 J.Cupitt
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* - externs fixed
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* - includes fixed
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* 13/2/95 JC
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* - ANSIfied
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* - cleaned up
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* 11/7/02 JC
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* - rewritten ... got rid of the stuff for handling -ves, never used
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* (and was broken anyway)
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* 1/2/10
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* - gtkdoc
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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 <math.h>
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#include <vips/vips.h>
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/**
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* im_scaleps:
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* @in: input image
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* @out: output image
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*
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* Scale a power spectrum. Transform with log10(1.0 + pow(x, 0.25)) + .5,
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* then scale so max == 255.
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*
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* See also: im_scale().
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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_scaleps( IMAGE *in, IMAGE *out )
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{
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IMAGE *t[4];
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double mx;
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double scale;
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if( im_open_local_array( out, t, 4, "im_scaleps-1", "p" ) ||
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im_max( in, &mx ) )
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return( -1 );
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if( mx <= 0.0 )
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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 / log10( 1.0 + pow( mx, .25 ) );
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/* Transform!
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*/
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if( im_powtra( in, t[0], 0.25 ) ||
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im_lintra( 1.0, t[0], 1.0, t[1] ) ||
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im_log10tra( t[1], t[2] ) ||
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im_lintra( scale, t[2], 0.0, t[3] ) ||
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im_clip2fmt( t[3], out, IM_BANDFMT_UCHAR ) )
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return( -1 );
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return( 0 );
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}
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