135 lines
2.9 KiB
C
135 lines
2.9 KiB
C
/* count lines
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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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* 23/10/10
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* - gtk-doc
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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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/**
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* im_cntlines:
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* @im: input #IMAGE
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* @nolines: output average number of lines
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* @flag: 0 horizontal, 1 vertical
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*
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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 one band, 8-bit.
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*
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* See also: im_erode().
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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_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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if( im_incheck( im ) ||
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im_check_uncoded( "im_cntlines", im ) ||
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im_check_mono( "im_cntlines", im ) ||
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im_check_format( "im_cntlines", im, IM_BANDFMT_UCHAR ) )
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return( -1 );
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if( flag != 0 && flag != 1 ) {
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im_error( "im_cntlines", "%s",
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_( "flag should be 0 (horizontal) 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] < 128 && p[1] >= 128 )
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cnt++;
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else if( p[0] >= 128 && p[1] < 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 < 128 && *p2 >= 128 )
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cnt++;
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else if( *p1 >= 128 && *p2 < 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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