85 lines
2.1 KiB
C
85 lines
2.1 KiB
C
/* Gamma-correct image with factor gammafactor.
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*
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* Copyright: 1990, N. Dessipris.
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*
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* Written on: 19/07/1990
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* Modified on:
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* 19/6/95 JC
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* - redone as library function
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* 23/3/10
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* - gtkdoc
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* - 16 bit as well
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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., 51 Franklin Street, Fifth Floor, Boston, MA
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02110-1301 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 <vips/vips.h>
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/**
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* im_gammacorrect:
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* @in: input image
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* @out: output image
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* @exponent: gamma factor
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*
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* Gamma-correct an 8- or 16-bit unsigned image with a lookup table. The
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* output format is the same as the input format.
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*
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* See also: im_identity(), im_powtra(), im_maplut()
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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_gammacorrect( IMAGE *in, IMAGE *out, double exponent )
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{
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IMAGE *t[4];
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double mx1, mx2;
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if( im_open_local_array( out, t, 4, "im_gammacorrect", "p" ) ||
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im_check_u8or16( "im_gammacorrect", in ) ||
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im_piocheck( in, out ) ||
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(in->BandFmt == IM_BANDFMT_UCHAR ?
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im_identity( t[0], 1 ) :
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im_identity_ushort( t[0], 1, 65536 )) ||
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im_powtra( t[0], t[1], exponent ) ||
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im_max( t[0], &mx1 ) ||
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im_max( t[1], &mx2 ) ||
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im_lintra( mx1 / mx2, t[1], 0, t[2] ) ||
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im_clip2fmt( t[2], t[3], in->BandFmt ) ||
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im_maplut( in, out, t[3] ) )
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return( -1 );
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return( 0 );
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}
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