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/* hough transform for lines
*
* 7/3/14
* - from hist_find.c
*/
/*
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., 51 Franklin Street, Fifth Floor, Boston, MA
02110-1301 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 <string.h>
#include <math.h>
#include <vips/vips.h>
#include "statistic.h"
#include "hough.h"
typedef struct _VipsHoughLine {
VipsHough parent_instance;
/* Size of parameter space.
*/
int width;
int height;
/* LUT for this transform.
*/
double *sin;
} VipsHoughLine;
typedef VipsHoughClass VipsHoughLineClass;
G_DEFINE_TYPE( VipsHoughLine, vips_hough_line, VIPS_TYPE_HOUGH );
static int
vips_hough_line_build( VipsObject *object )
{
VipsHoughLine *hough_line = (VipsHoughLine *) object;
int width = hough_line->width;
int i;
if( !(hough_line->sin = VIPS_ARRAY( object, width, double )) )
return( -1 );
for( i = 0; i < width; i++ )
hough_line->sin[i] = sin( 2 * VIPS_PI * i / width );
if( VIPS_OBJECT_CLASS( vips_hough_line_parent_class )->build( object ) )
return( -1 );
return( 0 );
}
static int
vips_hough_line_init_accumulator( VipsHough *hough, VipsImage *accumulator )
{
VipsHoughLine *hough_line = (VipsHoughLine *) hough;
vips_image_init_fields( accumulator,
hough_line->width, hough_line->height, 1,
VIPS_FORMAT_UINT, VIPS_CODING_NONE,
VIPS_INTERPRETATION_MATRIX,
1.0, 1.0 );
return( 0 );
}
/* Cast votes for all lines passing through x, y.
*/
static void
vips_hough_line_vote( VipsHough *hough, VipsImage *accumulator, int x, int y )
{
VipsHoughLine *hough_line = (VipsHoughLine *) hough;
VipsStatistic *statistic = (VipsStatistic *) hough;
double xd = (double) x / statistic->ready->Xsize;
double yd = (double) y / statistic->ready->Ysize;
int width = hough_line->width;
int height = hough_line->height;
int i;
for( i = 0; i < width; i++ ) {
int i90 = (i + width / 4) % width;
double r = xd * hough_line->sin[i90] + yd * hough_line->sin[i];
int ri = height * r;
if( ri >= 0 &&
ri < height )
*VIPS_IMAGE_ADDR( accumulator, i, ri ) += 1;
}
}
static void
vips_hough_line_class_init( VipsHoughClass *class )
{
GObjectClass *gobject_class = (GObjectClass *) class;
VipsObjectClass *object_class = (VipsObjectClass *) class;
VipsHoughClass *hclass = (VipsHoughClass *) class;
gobject_class->set_property = vips_object_set_property;
gobject_class->get_property = vips_object_get_property;
object_class->nickname = "hough_line";
object_class->description = _( "find hough line transform" );
object_class->build = vips_hough_line_build;
hclass->init_accumulator = vips_hough_line_init_accumulator;
hclass->vote = vips_hough_line_vote;
VIPS_ARG_INT( class, "width", 110,
_( "Width" ),
_( "horizontal size of parameter space" ),
VIPS_ARGUMENT_OPTIONAL_INPUT,
G_STRUCT_OFFSET( VipsHoughLine, width ),
1, 100000, 256 );
VIPS_ARG_INT( class, "height", 111,
_( "Height" ),
_( "Vertical size of parameter space" ),
VIPS_ARGUMENT_OPTIONAL_INPUT,
G_STRUCT_OFFSET( VipsHoughLine, height ),
1, 100000, 256 );
}
static void
vips_hough_line_init( VipsHoughLine *hough_line )
{
hough_line->width = 256;
hough_line->height = 256;
}
/**
* vips_hough_line:
* @in: input image
* @out: output image
* @...: %NULL-terminated list of optional named arguments
*
* Optional arguments:
*
* * @width: horizontal size of parameter space
* * @height: vertical size of parameter space
*
* Find the line Hough transform for @in. @in must have one band. @out has one
* band, with pixels being the number of votes for that line. The X dimension
* of @out is the line angle, the Y dimension is the distance of the line from
* the origin.
*
* Use @width @height to set the size of the parameter space image (@out),
* that is, how accurate the line determination should be.
*
* See also: vips_hough_circle().
*
* Returns: 0 on success, -1 on error
*/
int
vips_hough_line( VipsImage *in, VipsImage **out, ... )
{
va_list ap;
int result;
va_start( ap, out );
result = vips_call_split( "hough_line", ap, in, out );
va_end( ap );
return( result );
}
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