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/* Histogram-equalise an image.
*
* Copyright: 1991, N. Dessipris.
*
* Author: Nicos Dessipris
* Written on: 27/03/1991
* Modified on :
* 16/6/93 J.Cupitt
* - im_ioflag() changed to im_iocheck()
* 24/5/95 JC
* - ANSIfied and tidied up
* 3/3/01 JC
* - more cleanup
* 23/3/10
* - gtkdoc
* 12/8/13
* - redone as a class
* 19/6/17
* - make output format always == input format, thanks Simon
*/
/*
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., 51 Franklin Street, Fifth Floor, Boston, MA
02110-1301 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 <glib/gi18n-lib.h>
#include <stdio.h>
#include <vips/vips.h>
typedef struct _VipsHistEqual {
VipsOperation parent_instance;
VipsImage *in;
VipsImage *out;
/* -1 for all bands, or the band we scan.
*/
int which;
} VipsHistEqual;
typedef VipsOperationClass VipsHistEqualClass;
G_DEFINE_TYPE( VipsHistEqual, vips_hist_equal, VIPS_TYPE_OPERATION );
static int
vips_hist_equal_build( VipsObject *object )
{
VipsHistEqual *equal = (VipsHistEqual *) object;
VipsImage **t = (VipsImage **) vips_object_local_array( object, 5 );
g_object_set( equal, "out", vips_image_new(), NULL );
if( VIPS_OBJECT_CLASS( vips_hist_equal_parent_class )->build( object ) )
return( -1 );
/* norm can return a uchar output for a ushort input if the range is
* small, so make sure we cast back to the input type again.
*/
if( vips_hist_find( equal->in, &t[0],
"band", equal->which,
NULL ) ||
vips_hist_cum( t[0], &t[1], NULL ) ||
vips_hist_norm( t[1], &t[2], NULL ) ||
vips_cast( t[2], &t[3], equal->in->BandFmt, NULL ) ||
vips_maplut( equal->in, &t[4], t[3], NULL ) ||
vips_image_write( t[4], equal->out ) )
return( -1 );
return( 0 );
}
static void
vips_hist_equal_class_init( VipsHistEqualClass *class )
{
GObjectClass *gobject_class = G_OBJECT_CLASS( class );
VipsObjectClass *object_class = (VipsObjectClass *) class;
gobject_class->set_property = vips_object_set_property;
gobject_class->get_property = vips_object_get_property;
object_class->nickname = "hist_equal";
object_class->description = _( "histogram equalisation" );
object_class->build = vips_hist_equal_build;
VIPS_ARG_IMAGE( class, "in", 1,
_( "Input" ),
_( "Input image" ),
VIPS_ARGUMENT_REQUIRED_INPUT,
G_STRUCT_OFFSET( VipsHistEqual, in ) );
VIPS_ARG_IMAGE( class, "out", 2,
_( "Output" ),
_( "Output image" ),
VIPS_ARGUMENT_REQUIRED_OUTPUT,
G_STRUCT_OFFSET( VipsHistEqual, out ) );
VIPS_ARG_INT( class, "band", 110,
_( "Band" ),
_( "Equalise with this band" ),
VIPS_ARGUMENT_OPTIONAL_INPUT,
G_STRUCT_OFFSET( VipsHistEqual, which ),
-1, 100000, -1 );
}
static void
vips_hist_equal_init( VipsHistEqual *equal )
{
equal->which = -1;
}
/**
* vips_hist_equal: (method)
* @in: input image
* @out: (out): output image
* @...: %NULL-terminated list of optional named arguments
*
* Optional arguments:
*
* * @band: band to equalise
*
* Histogram-equalise @in. Equalise using band @bandno, or if @bandno is -1,
* equalise bands independently. The output format is always the same as the
* input format.
*
* See also:
*
* Returns: 0 on success, -1 on error
*/
int
vips_hist_equal( VipsImage *in, VipsImage **out, ... )
{
va_list ap;
int result;
va_start( ap, out );
result = vips_call_split( "hist_equal", ap, in, out );
va_end( ap );
return( result );
}
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