dp_gamma.c

Lido PXA270平台开发板的最新BSP,包括源代码

/*********************************************************************************
 *********************************************************************************
 **
 ** Name        : dp_gamma.c
 ** Title       : Gamma correction data generation functions
 ** Author      : P. Buxton
 ** Created     : June 2001
 ** 
 ** Copyright   : 2001 by Imagination Technologies Limited. All rights reserved
 **             : No part of this software, either material or conceptual
 **             : may be copied or distributed, transmitted, transcribed,
 **             : stored in a retrieval system or translated into any
 **             : human or computer language in any form by any means,
 **             : electronic, mechanical, manual or other-wise, or
 **             : disclosed to third parties without the express written
 **             : permission of Imagination Technologies Limited, Unit 8,
 **             : HomePark Industrial Estate, King's Langley, Hertfordshire,
 **             : WD4 8LZ, U.K.
 **
 ** Description : This file contains the functions, constant definitions, etc.
 **               necessary to generate gamma correction table values.
 **
 ** Platform    : Platform independent	(modify 'types.h' accordingly)
 ** $Log: dp_gamma.c $
 **
 **  --- Revision Logs Removed --- 
 **
 *********************************************************************************
 *********************************************************************************/

#include "dp_types.h"
#include "dp_init_marathon.h"
#include "dp_hardware.h"
#include "dp_hardware_dispatcher.h"


DP_UINT_8 DP_GammaCalc	(DP_UINT_16 nIndex,
						 DP_UINT_16 Gamma, 
						 DP_UINT_16 Range, 
						 DP_UINT_16 Brightness)
{
DP_UINT_8	wRetVal;
DP_DOUBLE	y;
DP_DOUBLE	x, range, gamma, brightness;
DP_DOUBLE   gammaX;

	x			=	nIndex;
	gamma		=	Gamma;
	gamma		=	gamma / 100;
	range		=	Range;
	brightness	=	Brightness;

	if ( x != 0.0 )
		gammaX = DP_POW ( (x/256), (1/gamma) ) * range;
	else
		gammaX = 0.0;

	y = (gammaX) + (brightness - 128) + ( 128 - (range / 2) ) ;

	if ( y > 255 )
		y = 255;

	if ( y < 0 )
		y = 0;

	wRetVal	=	(DP_UINT_8) y;

return wRetVal;
}


/*--------------------------- End of File --------------------------------*/