192 lines
4.6 KiB
C
192 lines
4.6 KiB
C
/* Raise an image to a gamma factor
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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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* 1/8/13
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* - redone as a class
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* 11/11/13
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* - any format
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* - calculate pow(1/exp) rather than pow(exp) to be consistent with
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* other packages
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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 <glib/gi18n-lib.h>
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#include <math.h>
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#include <vips/vips.h>
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#include "pconversion.h"
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typedef struct _VipsGamma {
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VipsConversion parent_instance;
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VipsImage *in;
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double exponent;
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} VipsGamma;
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typedef VipsConversionClass VipsGammaClass;
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G_DEFINE_TYPE( VipsGamma, vips_gamma, VIPS_TYPE_CONVERSION );
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/* For each input format, what we normalise the pow() about.
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*/
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static double vips_gamma_maxval[10] = {
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/* UC */ UCHAR_MAX,
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/* C */ SCHAR_MAX,
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/* US */ USHRT_MAX,
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/* S */ SHRT_MAX,
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/* UI */ UINT_MAX,
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/* I */ INT_MAX,
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/* F */ 1.0,
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/* X */ 1.0,
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/* D */ 1.0,
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/* DX */ 1.0
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};
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static int
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vips_gamma_build( VipsObject *object )
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{
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VipsConversion *conversion = VIPS_CONVERSION( object );
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VipsGamma *gamma = (VipsGamma *) object;
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VipsImage **t = (VipsImage **) vips_object_local_array( object, 5 );
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VipsImage *in = gamma->in;
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double scale;
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if( VIPS_OBJECT_CLASS( vips_gamma_parent_class )->
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build( object ) )
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return( -1 );
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scale = pow( vips_gamma_maxval[in->BandFmt],
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1.0 / gamma->exponent ) /
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vips_gamma_maxval[in->BandFmt];
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if( in->BandFmt == VIPS_FORMAT_UCHAR ||
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in->BandFmt == VIPS_FORMAT_USHORT ) {
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if( vips_identity( &t[0],
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"ushort", in->BandFmt == VIPS_FORMAT_USHORT,
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NULL ) ||
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vips_pow_const1( t[0], &t[1],
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1.0 / gamma->exponent, NULL ) ||
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vips_linear1( t[1], &t[2], 1.0 / scale, 0, NULL ) ||
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vips_cast( t[2], &t[3], in->BandFmt, NULL ) ||
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vips_maplut( in, &t[4], t[3], NULL ) ||
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vips_image_write( t[4], conversion->out ) )
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return( -1 );
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}
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else {
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if( vips_pow_const1( in, &t[1],
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1.0 / gamma->exponent, NULL ) ||
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vips_linear1( t[1], &t[2], 1.0 / scale, 0, NULL ) ||
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vips_cast( t[2], &t[3], in->BandFmt, NULL ) ||
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vips_image_write( t[3], conversion->out ) )
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return( -1 );
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}
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return( 0 );
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}
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static void
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vips_gamma_class_init( VipsGammaClass *class )
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{
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GObjectClass *gobject_class = G_OBJECT_CLASS( class );
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VipsObjectClass *vobject_class = VIPS_OBJECT_CLASS( class );
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VipsOperationClass *operation_class = VIPS_OPERATION_CLASS( class );
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gobject_class->set_property = vips_object_set_property;
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gobject_class->get_property = vips_object_get_property;
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vobject_class->nickname = "gamma";
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vobject_class->description = _( "gamma an image" );
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vobject_class->build = vips_gamma_build;
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operation_class->flags = VIPS_OPERATION_SEQUENTIAL;
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VIPS_ARG_IMAGE( class, "in", 1,
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_( "Input" ),
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_( "Input image" ),
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VIPS_ARGUMENT_REQUIRED_INPUT,
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G_STRUCT_OFFSET( VipsGamma, in ) );
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VIPS_ARG_DOUBLE( class, "exponent", 2,
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_( "Exponent" ),
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_( "Gamma factor" ),
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VIPS_ARGUMENT_OPTIONAL_INPUT,
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G_STRUCT_OFFSET( VipsGamma, exponent ),
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0.000001, 1000.0, 2.4 );
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}
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static void
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vips_gamma_init( VipsGamma *gamma )
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{
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gamma->exponent = 1.0 / 2.4;
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}
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/**
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* vips_gamma: (method)
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* @in: input image
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* @out: (out): output image
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* @...: %NULL-terminated list of optional named arguments
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*
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* Optional arguments:
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*
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* * @exponent: gamma, default 1.0 / 2.4
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*
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* Calculate @in ** (1 / @exponent), normalising to the maximum range of the
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* input type. For float types use 1.0 as the maximum.
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*
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* See also: vips_identity(), vips_pow_const1(), vips_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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vips_gamma( VipsImage *in, VipsImage **out, ... )
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{
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va_list ap;
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int result;
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va_start( ap, out );
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result = vips_call_split( "gamma", ap, in, out );
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va_end( ap );
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return( result );
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}
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