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/* histogram normalisation
*
* Author: N. Dessipris
* Written on: 02/08/1990
* 24/5/95 JC
* - tidied up and ANSIfied
* 20/7/95 JC
* - smartened up again
* - now works for hists >256 elements
* 3/3/01 JC
* - broken into norm and norm ... helps im_histspec()
* - better behaviour for >8 bit hists
* 31/10/05 JC
* - was broken for vertical histograms, gah
* - neater im_histnorm()
* 23/7/07
* - eek, off by 1 for more than 1 band hists
* 12/5/08
* - histnorm works for signed hists now as well
* 24/3/10
* - gtkdoc
* - small cleanups
* 12/8/13
* - redone im_histnorm() as a class, vips_hist_norm()
*/
/*
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 _VipsHistNorm {
VipsOperation parent_instance;
VipsImage *in;
VipsImage *out;
} VipsHistNorm;
typedef VipsOperationClass VipsHistNormClass;
G_DEFINE_TYPE( VipsHistNorm, vips_hist_norm, VIPS_TYPE_OPERATION );
static int
vips_hist_norm_build( VipsObject *object )
{
VipsHistNorm *norm = (VipsHistNorm *) object;
VipsImage **t = (VipsImage **) vips_object_local_array( object, 3 );
guint64 new_max;
int bands;
double *a, *b;
int y;
VipsBandFormat fmt;
g_object_set( object, "out", vips_image_new(), NULL );
if( VIPS_OBJECT_CLASS( vips_hist_norm_parent_class )->build( object ) )
return( -1 );
/* Need max for each channel.
*/
if( vips_stats( norm->in, &t[0], NULL ) )
return( -1 );
/* Scale each channel by px / channel max
*/
new_max = VIPS_IMAGE_N_PELS( norm->in ) - 1;
bands = norm->in->Bands;
if( !(a = VIPS_ARRAY( object, bands, double )) ||
!(b = VIPS_ARRAY( object, bands, double )) )
return( -1 );
for( y = 0; y < bands; y++ ) {
a[y] = new_max / *VIPS_MATRIX( t[0], 1, y + 1 );
b[y] = 0;
}
if( vips_linear( norm->in, &t[1], a, b, bands, NULL ) )
return( -1 );
/* Make output format as small as we can.
*/
if( new_max <= 255 )
fmt = VIPS_FORMAT_UCHAR;
else if( new_max <= 65535 )
fmt = VIPS_FORMAT_USHORT;
else
fmt = VIPS_FORMAT_UINT;
if( vips_cast( t[1], &t[2], fmt, NULL ) ||
vips_image_write( t[2], norm->out ) )
return( -1 );
return( 0 );
}
static void
vips_hist_norm_class_init( VipsHistNormClass *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_norm";
object_class->description = _( "normalise histogram" );
object_class->build = vips_hist_norm_build;
VIPS_ARG_IMAGE( class, "in", 1,
_( "Input" ),
_( "Input image" ),
VIPS_ARGUMENT_REQUIRED_INPUT,
G_STRUCT_OFFSET( VipsHistNorm, in ) );
VIPS_ARG_IMAGE( class, "out", 2,
_( "Output" ),
_( "Output image" ),
VIPS_ARGUMENT_REQUIRED_OUTPUT,
G_STRUCT_OFFSET( VipsHistNorm, out ) );
}
static void
vips_hist_norm_init( VipsHistNorm *hist_norm )
{
}
/**
* vips_hist_norm: (method)
* @in: input image
* @out: (out): output image
* @...: %NULL-terminated list of optional named arguments
*
* Normalise histogram. The maximum of each band becomes equal to the maximum
* index, so for example the max for a uchar image becomes 255.
* Normalise each band separately.
*
* See also: vips_hist_cum().
*
* Returns: 0 on success, -1 on error
*/
int
vips_hist_norm( VipsImage *in, VipsImage **out, ... )
{
va_list ap;
int result;
va_start( ap, out );
result = vips_call_split( "hist_norm", ap, in, out );
va_end( ap );
return( result );
}
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