230 lines
5.1 KiB
C
230 lines
5.1 KiB
C
/* histogram normalisation and cumulativisation
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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 cum 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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* - histcum 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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*/
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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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#define ACCUMULATE( ITYPE, OTYPE ) { \
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for( b = 0; b < nb; b++ ) { \
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ITYPE *p = (ITYPE *) in->data; \
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OTYPE *q = (OTYPE *) outbuf; \
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OTYPE total; \
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\
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total = 0; \
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for( x = b; x < mx; x += nb ) { \
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total += p[x]; \
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q[x] = total; \
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} \
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} \
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}
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/**
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* im_histcum:
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* @in: input image
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* @out: output image
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*
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* Form cumulative histogram.
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*
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* See also: im_histnorm().
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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_histcum( IMAGE *in, IMAGE *out )
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{
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const guint64 px = VIPS_IMAGE_N_PELS( in );
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const int nb = vips_bandfmt_iscomplex( in->BandFmt ) ?
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in->Bands * 2 : in->Bands;
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const guint64 mx = px * nb;
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VipsPel *outbuf;
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guint64 b, x;
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if( im_check_uncoded( "im_histcum", in ) ||
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im_check_hist( "im_histcum", in ) ||
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im_iocheck( in, out ) )
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return( -1 );
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if( im_cp_desc( out, in ) )
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return( -1 );
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out->Xsize = px;
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out->Ysize = 1;
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if( vips_bandfmt_isuint( in->BandFmt ) )
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out->BandFmt = IM_BANDFMT_UINT;
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else if( vips_bandfmt_isint( in->BandFmt ) )
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out->BandFmt = IM_BANDFMT_INT;
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if( im_setupout( out ) )
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return( -1 );
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if( !(outbuf = im_malloc( out, IM_IMAGE_SIZEOF_LINE( out ))) )
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return( -1 );
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switch( in->BandFmt ) {
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case IM_BANDFMT_CHAR:
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ACCUMULATE( signed char, signed int ); break;
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case IM_BANDFMT_UCHAR:
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ACCUMULATE( unsigned char, unsigned int ); break;
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case IM_BANDFMT_SHORT:
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ACCUMULATE( signed short, signed int ); break;
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case IM_BANDFMT_USHORT:
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ACCUMULATE( unsigned short, unsigned int ); break;
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case IM_BANDFMT_INT:
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ACCUMULATE( signed int, signed int ); break;
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case IM_BANDFMT_UINT:
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ACCUMULATE( unsigned int, unsigned int ); break;
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case IM_BANDFMT_FLOAT:
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case IM_BANDFMT_COMPLEX:
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ACCUMULATE( float, float ); break;
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case IM_BANDFMT_DOUBLE:
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case IM_BANDFMT_DPCOMPLEX:
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ACCUMULATE( double, double ); break;
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default:
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g_assert( 0 );
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}
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if( im_writeline( 0, out, outbuf ) )
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return( -1 );
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return( 0 );
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}
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/**
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* im_histnorm:
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* @in: input image
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* @out: output image
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*
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* Normalise histogram ... normalise range to make it square (ie. max ==
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* number of elements). Normalise each band separately.
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*
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* See also: im_histcum().
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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_histnorm( IMAGE *in, IMAGE *out )
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{
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const guint64 px = VIPS_IMAGE_N_PELS( in );
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DOUBLEMASK *stats;
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double *a, *b;
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int y;
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IMAGE *t1;
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int fmt;
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/* Need max for each channel.
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*/
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if( !(a = IM_ARRAY( out, in->Bands, double )) ||
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!(b = IM_ARRAY( out, in->Bands, double )) ||
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!(stats = im_stats( in )) )
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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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for( y = 0; y < in->Bands; y++ ) {
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a[y] = px / VIPS_MASK( stats, 1, y + 1 );
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b[y] = 0;
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}
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im_free_dmask( stats );
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if( !(t1 = im_open_local( out, "im_histnorm:2", "p" )) ||
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im_lintra_vec( in->Bands, a, in, b, t1 ) )
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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( px <= 256 )
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fmt = IM_BANDFMT_UCHAR;
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else if( px <= 65536 )
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fmt = IM_BANDFMT_USHORT;
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else
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fmt = IM_BANDFMT_UINT;
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if( im_clip2fmt( t1, out, fmt ) )
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return( -1 );
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return( 0 );
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}
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/**
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* im_histeq:
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* @in: input image
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* @out: output image
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*
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* Histogram equalisation: normalised cumulative histogram.
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*
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* See also: im_heq().
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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_histeq( IMAGE *in, IMAGE *out )
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{
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IMAGE *t1;
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/* Normalised cumulative.
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*/
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if( !(t1 = im_open_local( out, "im_histeq", "p" )) ||
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im_histcum( in, t1 ) ||
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im_histnorm( t1, out ) )
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return( -1 );
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return( 0 );
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}
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