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/* Turn Lab to LCh
*
* 2/11/09
* - gtkdoc
* - cleanups
* 18/9/12
* - redone as a class
*/
/*
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 <stdio.h>
#include <math.h>
#include <vips/vips.h>
#include "pcolour.h"
typedef VipsColourTransform VipsLab2LCh;
typedef VipsColourTransformClass VipsLab2LChClass;
G_DEFINE_TYPE( VipsLab2LCh, vips_Lab2LCh, VIPS_TYPE_COLOUR_TRANSFORM );
/**
* vips_col_ab2h:
* @a: CIE a
* @b: CIE b
*
* Returns: Hue (degrees)
*/
double
vips_col_ab2h( double a, double b )
{
double h;
#ifdef HAVE_ATAN2
h = VIPS_DEG( atan2( b, a ) );
if( h < 0.0 )
h += 360;
#else
/* We have to get the right quadrant!
*/
if( a == 0 ) {
if( b < 0.0 )
h = 270;
else if( b == 0.0 )
h = 0;
else
h = 90;
}
else {
double t = atan( b / a );
if( a > 0.0 )
if( b < 0.0 )
h = VIPS_DEG( t + VIPS_PI * 2.0 );
else
h = VIPS_DEG( t );
else
h = VIPS_DEG( t + VIPS_PI );
}
#endif
return( h );
}
void
vips_col_ab2Ch( float a, float b, float *C, float *h )
{
#ifdef HAVE_ATAN2
*h = VIPS_DEG( atan2( b, a ) );
if( *h < 0.0 )
*h += 360;
#else
*h = vips_col_ab2h( a, b );
#endif
#ifdef HAVE_HYPOT
*C = hypot( a, b );
#else
*C = sqrt( a * a + b * b );
#endif
}
static void
vips_Lab2LCh_line( VipsColour *colour, VipsPel *out, VipsPel **in, int width )
{
float * restrict p = (float *) in[0];
float * restrict q = (float *) out;
int x;
for( x = 0; x < width; x++ ) {
float L = p[0];
float a = p[1];
float b = p[2];
float C, h;
p += 3;
C = sqrt( a * a + b * b );
h = vips_col_ab2h( a, b );
q[0] = L;
q[1] = C;
q[2] = h;
q += 3;
}
}
static void
vips_Lab2LCh_class_init( VipsLab2LChClass *class )
{
VipsObjectClass *object_class = (VipsObjectClass *) class;
VipsColourClass *colour_class = VIPS_COLOUR_CLASS( class );
object_class->nickname = "Lab2LCh";
object_class->description = _( "transform Lab to LCh" );
colour_class->process_line = vips_Lab2LCh_line;
}
static void
vips_Lab2LCh_init( VipsLab2LCh *Lab2LCh )
{
VipsColour *colour = VIPS_COLOUR( Lab2LCh );
colour->interpretation = VIPS_INTERPRETATION_LCH;
}
/**
* vips_Lab2LCh:
* @in: input image
* @out: output image
* @...: %NULL-terminated list of optional named arguments
*
* Turn Lab to LCh.
*
* Returns: 0 on success, -1 on error
*/
int
vips_Lab2LCh( VipsImage *in, VipsImage **out, ... )
{
va_list ap;
int result;
va_start( ap, out );
result = vips_call_split( "Lab2LCh", ap, in, out );
va_end( ap );
return( result );
}
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