//-----------------------------------------------------------------------------
// Copyright © 2006 - Philip Howard - All rights reserved
//
// This program is free software; you can redistribute it and/or
// modify it under the terms of the GNU 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 General Public License for more details.
//
// You should have received a copy of the GNU 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.
//-----------------------------------------------------------------------------
// package	libh/arith
// homepage	http://libh.slashusr.org/
//-----------------------------------------------------------------------------
// author	Philip Howard
// email	libh at ipal dot org
// homepage	http://phil.ipal.org/
//-----------------------------------------------------------------------------
// This file is best viewed using a fixed spaced font such as Courier
// and in a display at least 120 columns wide.
//-----------------------------------------------------------------------------

__FMACRO_BEGIN__
//-----------------------------------------------------------------------------
// macro	pix_itof
//
// purpose	Convert an integer (int) pixel intensity value in the range
//		0 .. N-1 to a gamma adjusted floating point (double pixel
//		intensity value in the range 0.0 .. 1.0.
//
// arguments	1 (double) gamma correction factor to use
//		2 (int) pixel intensity from 0 to N-1
//		3 (int) integer scale N
//
// returns	(double) pixel intensity in the range 0.0 .. 1.0
//-----------------------------------------------------------------------------
#define pix_itof(g,v,s) ({							\
	int	libh__value;							\
	int	libh__scale;							\
	libh__value = (v);							\
	libh__scale = (s);							\
	( libh__scale <= 1 ) ? 0.0 :						\
	( libh__value >= libh__scale ) ? 1.0 :					\
	( libh__value <= 0 ) ? 0.0 :						\
	({	double	libh__gvtmp;						\
		libh__gvtmp = (g);						\
		if ( libh__gvtmp <= 0.0 ) libh__gvtmp = PIX_DEFAULT_GAMMA;	\
		libh__gvtmp = exp( log( (double) libh__value / (double) ( libh__scale - 1 ) ) * libh__gvtmp );	\
		( libh__gvtmp <= 0.0 ) ? 0.0 : ( libh__gvtmp >= 1.0 ) ? 1.0 : libh__gvtmp;			\
	})									\
})

__FMACRO_END__