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