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/* im_compass
*
* Author: N. Dessipris (Copyright, N. Dessipris 1991)
* Written on: 08/05/1991
* Modified on:
* 11/3/01 JC
* - rewritten, calling im_conv() and im_maxvalue()
* 3/2/10
* - gtkdoc
*/
/*
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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 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 <vips/intl.h>
#include <vips/vips.h>
/**
* im_compass:
* @in: input image
* @out: output image
* @mask: convolution mask
*
* @in is convolved 8 times with @mask, each time @mask is rotated by 45
* degrees. Each output pixel is the largest absolute value of the 8
* convolutions.
*
* See also: im_lindetect(), im_gradient(), im_conv().
*
* Returns: 0 on success, -1 on error
*/
int
im_compass( IMAGE *in, IMAGE *out, INTMASK *mask )
{
IMAGE *filtered[8];
IMAGE *absed[8];
int i;
if( im_open_local_array( out, filtered, 8, "im_compass:1", "p" ) ||
im_open_local_array( out, absed, 8, "im_compass:2", "p" ) )
return( -1 );
for( i = 0; i < 8; i++ ) {
if( im_conv( in, filtered[i], mask ) ||
!(mask = im_local_imask( out,
im_rotate_imask45( mask, mask->filename ) )) )
return( -1 );
}
for( i = 0; i < 8; i++ )
if( im_abs( filtered[i], absed[i] ) )
return( -1 );
return( im_maxvalue( absed, out, 8 ) );
}
/**
* im_lindetect:
* @in: input image
* @out: output image
* @mask: convolution mask
*
* @in is convolved four times with @mask, each time @mask is rotated by 45
* degrees. Each output pixel is the largest absolute value of the four
* convolutions.
*
* See also: im_compass(), im_gradient(), im_conv().
*
* Returns: 0 on success, -1 on error
*/
int
im_lindetect( IMAGE *in, IMAGE *out, INTMASK *mask )
{
IMAGE *filtered[4];
IMAGE *absed[4];
int i;
if( im_open_local_array( out, filtered, 4, "im_lindetect:1", "p" ) ||
im_open_local_array( out, absed, 4, "im_lindetect:2", "p" ) )
return( -1 );
for( i = 0; i < 4; i++ ) {
if( im_conv( in, filtered[i], mask ) ||
!(mask = im_local_imask( out,
im_rotate_imask45( mask, mask->filename ) )) )
return( -1 );
}
for( i = 0; i < 4; i++ )
if( im_abs( filtered[i], absed[i] ) )
return( -1 );
return( im_maxvalue( absed, out, 4 ) );
}
/**
* im_gradient:
* @in: input image
* @out: output image
* @mask: convolution mask
*
* @in is convolved with @mask and with @mask after a 90 degree rotation. The
* result is the sum of the absolute value of the two convolutions.
*
* See also: im_lindetect(), im_gradient(), im_conv().
*
* Returns: 0 on success, -1 on error
*/
int
im_gradient( IMAGE *in, IMAGE *out, INTMASK *mask )
{
IMAGE *t[4];
INTMASK *rmask;
if( im_open_local_array( out, t, 4, "im_gradient", "p" ) )
return( -1 );
if( !(rmask = im_local_imask( out,
im_rotate_imask90( mask, mask->filename ) )) )
return( -1 );
if( im_conv( in, t[0], mask ) ||
im_conv( in, t[1], rmask ) ||
im_abs( t[0], t[2] ) ||
im_abs( t[1], t[3] ) ||
im_add( t[2], t[3], out ) )
return( -1 );
return( 0 );
}
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