/* Turn Lab to LCh
 *
 * 2/11/09
 * 	- gtkdoc
 * 	- cleanups
 */

/*

    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 <stdio.h>
#include <math.h>

#include <vips/vips.h>

#ifdef WITH_DMALLOC
#include <dmalloc.h>
#endif /*WITH_DMALLOC*/

/* Our main loop.
 */
void
imb_Lab2LCh( float *p, float *q, int n )
{
	int x;

	for( x = 0; x < n; 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 = im_col_ab2h( a, b );

		q[0] = L;
		q[1] = C;
		q[2] = h;

		q += 3;
	}
}

int
im__colour_unary( const char *domain,
	IMAGE *in, IMAGE *out, VipsType type,
	im_wrapone_fn buffer_fn, void *a, void *b )
{
	IMAGE *t[1];

	if( im_check_uncoded( domain, in ) ||
		im_check_bands( domain, in, 3 ) ||
		im_open_local_array( out, t, 1, domain, "p" ) ||
		im_clip2fmt( in, t[0], IM_BANDFMT_FLOAT ) )
		return( -1 );

	if( im_cp_desc( out, t[0] ) )
		return( -1 );
	out->Type = type;

	if( im_wrapone( t[0], out, 
		(im_wrapone_fn) buffer_fn, a, b ) )
		return( -1 );

	return( 0 );
}

/**
 * im_Lab2LCh:
 * @in: input image
 * @out: output image
 *
 * Turn Lab to LCh.
 *
 * Returns: 0 on success, -1 on error.
 */
int 
im_Lab2LCh( IMAGE *in, IMAGE *out )
{
	return( im__colour_unary( "im_Lab2LCh", in, out, IM_TYPE_LCH,
		(im_wrapone_fn) imb_Lab2LCh, NULL, NULL ) );
}