132 lines
3.0 KiB
C
132 lines
3.0 KiB
C
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/* @(#) Function which calculates the number of transitions
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* @(#) between black and white for the horizontal or the vertical
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* @(#) direction of an image. black<128 , white>=128
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* @(#) The function calculates the number of transitions for all
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* @(#) Xsize or Ysize and returns the mean of the result
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* @(#) Input should be binary one channel
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* @(#)
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* @(#) int im_cntlines(im, nolines, flag)
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* @(#) IMAGE *im;
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* @(#) float *nolines;
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* @(#) int flag; 0 to cnt horizontal and 1 to count vertical lines
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* @(#)
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* @(#) Returns 0 on success and -1 on error
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*
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* Copyright: 1990, N. Dessipris.
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*
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* Author: Nicos Dessipris
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* Written on: 02/05/1990
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* Modified on :
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*
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* 19/9/95 JC
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* - tidied up
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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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 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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#ifdef WITH_DMALLOC
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#include <dmalloc.h>
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#endif /*WITH_DMALLOC*/
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int
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im_cntlines( IMAGE *im, double *nolines, int flag )
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{
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int x, y;
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PEL *line;
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int cnt;
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/* Is im valid?
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*/
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if( im_incheck( im ) )
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return( -1 );
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if( im->Coding != IM_CODING_NONE || im->BandFmt != IM_BANDFMT_UCHAR ||
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im->Bands != 1 ) {
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im_errormsg( "im_cntlines: 1-band uchar uncoded only" );
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return( -1 );
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}
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if( flag != 0 && flag != 1 ) {
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im_errormsg( "im_cntlines: flag should be 0 (horizontal) "
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"or 1 (vertical)" );
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return( -1 );
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}
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line = (PEL *) im->data;
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if( flag == 1 ) {
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/* Count vertical lines.
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*/
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for( cnt = 0, y = 0; y < im->Ysize; y++ ) {
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PEL *p = line;
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for( x = 0; x < im->Xsize - 1; x++ ) {
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if( p[0] < (PEL)128 && p[1] >= (PEL)128 )
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cnt++;
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else if( p[0] >= (PEL)128 && p[1] < (PEL)128 )
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cnt++;
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p++;
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}
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line += im->Xsize;
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}
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*nolines = (float) cnt / (2.0 * im->Ysize);
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}
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else {
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/* Count horizontal lines.
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*/
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for( cnt = 0, y = 0; y < im->Ysize - 1; y++ ) {
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PEL *p1 = line;
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PEL *p2 = line + im->Xsize;
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for( x = 0; x < im->Xsize; x++ ) {
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if( *p1 < (PEL)128 && *p2 >= (PEL)128 )
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cnt++;
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else if( *p1 >= (PEL)128 && *p2 < (PEL)128 )
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cnt++;
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p1++;
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p2++;
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}
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line += im->Xsize;
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}
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*nolines = (float)cnt / (2.0 * im->Xsize);
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}
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return( 0 );
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}
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