/* $Id: tif_color.c,v 1.19 2010-12-14 02:22:42 faxguy Exp $ */

/*

 * Copyright (c) 1988-1997 Sam Leffler

 * Copyright (c) 1991-1997 Silicon Graphics, Inc.

 *

 * Permission to use, copy, modify, distribute, and sell this software and 

 * its documentation for any purpose is hereby granted without fee, provided

 * that (i) the above copyright notices and this permission notice appear in

 * all copies of the software and related documentation, and (ii) the names of

 * Sam Leffler and Silicon Graphics may not be used in any advertising or

 * publicity relating to the software without the specific, prior written

 * permission of Sam Leffler and Silicon Graphics.

 * 

 * THE SOFTWARE IS PROVIDED "AS-IS" AND WITHOUT WARRANTY OF ANY KIND, 

 * EXPRESS, IMPLIED OR OTHERWISE, INCLUDING WITHOUT LIMITATION, ANY 

 * WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.  

 * 

 * IN NO EVENT SHALL SAM LEFFLER OR SILICON GRAPHICS BE LIABLE FOR

 * ANY SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY KIND,

 * OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,

 * WHETHER OR NOT ADVISED OF THE POSSIBILITY OF DAMAGE, AND ON ANY THEORY OF 

 * LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE 

 * OF THIS SOFTWARE.

 */

/*

 * CIE L*a*b* to CIE XYZ and CIE XYZ to RGB conversion routines are taken

 * from the VIPS library (http://www.vips.ecs.soton.ac.uk) with

 * the permission of John Cupitt, the VIPS author.

 */

/*

 * TIFF Library.

 *

 * Color space conversion routines.

 */

#include "tiffiop.h"

#include <math.h></math.h>

/*

 * Convert color value from the CIE L*a*b* 1976 space to CIE XYZ.

 */

void

TIFFCIELabToXYZ(TIFFCIELabToRGB *cielab, uint32 l, int32 a, int32 b,

		float *X, float *Y, float *Z)

{

	float L = (float)l * 100.0F / 255.0F;

	float cby, tmp;

	if( L < 8.856F ) {

		*Y = (L * cielab->Y0) / 903.292F;

		cby = 7.787F * (*Y / cielab->Y0) + 16.0F / 116.0F;

	} else {

		cby = (L + 16.0F) / 116.0F;

		*Y = cielab->Y0 * cby * cby * cby;

	}

	tmp = (float)a / 500.0F + cby;

	if( tmp < 0.2069F )

		*X = cielab->X0 * (tmp - 0.13793F) / 7.787F;

	else    

		*X = cielab->X0 * tmp * tmp * tmp;

	tmp = cby - (float)b / 200.0F;

	if( tmp < 0.2069F )

		*Z = cielab->Z0 * (tmp - 0.13793F) / 7.787F;

	else    

		*Z = cielab->Z0 * tmp * tmp * tmp;

}

#define RINT(R) ((uint32)((R)>0?((R)+0.5):((R)-0.5)))

/*

 * Convert color value from the XYZ space to RGB.

 */

void

TIFFXYZToRGB(TIFFCIELabToRGB *cielab, float X, float Y, float Z,

	     uint32 *r, uint32 *g, uint32 *b)

{

	int i;

	float Yr, Yg, Yb;

	float *matrix = &cielab->display.d_mat[0][0];

	/* Multiply through the matrix to get luminosity values. */

	Yr =  matrix[0] * X + matrix[1] * Y + matrix[2] * Z;

	Yg =  matrix[3] * X + matrix[4] * Y + matrix[5] * Z;

	Yb =  matrix[6] * X + matrix[7] * Y + matrix[8] * Z;

	/* Clip input */

	Yr = TIFFmax(Yr, cielab->display.d_Y0R);

	Yg = TIFFmax(Yg, cielab->display.d_Y0G);

	Yb = TIFFmax(Yb, cielab->display.d_Y0B);

	/* Avoid overflow in case of wrong input values */

	Yr = TIFFmin(Yr, cielab->display.d_YCR);

	Yg = TIFFmin(Yg, cielab->display.d_YCG);

	Yb = TIFFmin(Yb, cielab->display.d_YCB);

	/* Turn luminosity to colour value. */

	i = (int)((Yr - cielab->display.d_Y0R) / cielab->rstep);

	i = TIFFmin(cielab->range, i);

	*r = RINT(cielab->Yr2r[i]);

	i = (int)((Yg - cielab->display.d_Y0G) / cielab->gstep);

	i = TIFFmin(cielab->range, i);

	*g = RINT(cielab->Yg2g[i]);

	i = (int)((Yb - cielab->display.d_Y0B) / cielab->bstep);

	i = TIFFmin(cielab->range, i);

	*b = RINT(cielab->Yb2b[i]);

	/* Clip output. */

	*r = TIFFmin(*r, cielab->display.d_Vrwr);

	*g = TIFFmin(*g, cielab->display.d_Vrwg);

	*b = TIFFmin(*b, cielab->display.d_Vrwb);

}

#undef RINT

/* 

 * Allocate conversion state structures and make look_up tables for

 * the Yr,Yb,Yg <=> r,g,b conversions.

 */

int

TIFFCIELabToRGBInit(TIFFCIELabToRGB* cielab,

		    const TIFFDisplay *display, float *refWhite)

{

	int i;

	double gamma;

	cielab->range = CIELABTORGB_TABLE_RANGE;

	_TIFFmemcpy(&cielab->display, display, sizeof(TIFFDisplay));

	/* Red */

	gamma = 1.0 / cielab->display.d_gammaR ;

	cielab->rstep =

		(cielab->display.d_YCR - cielab->display.d_Y0R)	/ cielab->range;

	for(i = 0; i <= cielab->range; i++) {

		cielab->Yr2r[i] = cielab->display.d_Vrwr

		    * ((float)pow((double)i / cielab->range, gamma));

	}

	/* Green */

	gamma = 1.0 / cielab->display.d_gammaG ;

	cielab->gstep =

	    (cielab->display.d_YCR - cielab->display.d_Y0R) / cielab->range;

	for(i = 0; i <= cielab->range; i++) {

		cielab->Yg2g[i] = cielab->display.d_Vrwg

		    * ((float)pow((double)i / cielab->range, gamma));

	}

	/* Blue */

	gamma = 1.0 / cielab->display.d_gammaB ;

	cielab->bstep =

	    (cielab->display.d_YCR - cielab->display.d_Y0R) / cielab->range;

	for(i = 0; i <= cielab->range; i++) {

		cielab->Yb2b[i] = cielab->display.d_Vrwb

		    * ((float)pow((double)i / cielab->range, gamma));

	}

	/* Init reference white point */

	cielab->X0 = refWhite[0];

	cielab->Y0 = refWhite[1];

	cielab->Z0 = refWhite[2];

	return 0;

}

/* 

 * Convert color value from the YCbCr space to CIE XYZ.

 * The colorspace conversion algorithm comes from the IJG v5a code;

 * see below for more information on how it works.

 */

#define	SHIFT			16

#define	FIX(x)			((int32)((x) * (1L<

#define	ONE_HALF		((int32)(1<<(SHIFT-1)))

#define	Code2V(c, RB, RW, CR)	((((c)-(int32)(RB))*(float)(CR))/(float)(((RW)-(RB)) ? ((RW)-(RB)) : 1))

#define	CLAMP(f,min,max)	((f)<(min)?(min):(f)>(max)?(max):(f))

#define HICLAMP(f,max)		((f)>(max)?(max):(f))

void

TIFFYCbCrtoRGB(TIFFYCbCrToRGB *ycbcr, uint32 Y, int32 Cb, int32 Cr,

	       uint32 *r, uint32 *g, uint32 *b)

{

	int32 i;

	/* XXX: Only 8-bit YCbCr input supported for now */

	Y = HICLAMP(Y, 255), Cb = CLAMP(Cb, 0, 255), Cr = CLAMP(Cr, 0, 255);

	i = ycbcr->Y_tab[Y] + ycbcr->Cr_r_tab[Cr];

	*r = CLAMP(i, 0, 255);

	i = ycbcr->Y_tab[Y]

	    + (int)((ycbcr->Cb_g_tab[Cb] + ycbcr->Cr_g_tab[Cr]) >> SHIFT);

	*g = CLAMP(i, 0, 255);

	i = ycbcr->Y_tab[Y] + ycbcr->Cb_b_tab[Cb];

	*b = CLAMP(i, 0, 255);

}

/*

 * Initialize the YCbCr->RGB conversion tables.  The conversion

 * is done according to the 6.0 spec:

 *

 *    R = Y + Cr*(2 - 2*LumaRed)

 *    B = Y + Cb*(2 - 2*LumaBlue)

 *    G =   Y

 *        - LumaBlue*Cb*(2-2*LumaBlue)/LumaGreen

 *        - LumaRed*Cr*(2-2*LumaRed)/LumaGreen

 *

 * To avoid floating point arithmetic the fractional constants that

 * come out of the equations are represented as fixed point values

 * in the range 0...2^16.  We also eliminate multiplications by

 * pre-calculating possible values indexed by Cb and Cr (this code

 * assumes conversion is being done for 8-bit samples).

 */

int

TIFFYCbCrToRGBInit(TIFFYCbCrToRGB* ycbcr, float *luma, float *refBlackWhite)

{

    TIFFRGBValue* clamptab;

    int i;

#define LumaRed	    luma[0]

#define LumaGreen   luma[1]

#define LumaBlue    luma[2]

    clamptab = (TIFFRGBValue*)(

	(uint8*) ycbcr+TIFFroundup_32(sizeof (TIFFYCbCrToRGB), sizeof (long)));  

    _TIFFmemset(clamptab, 0, 256);		/* v < 0 => 0 */

    ycbcr->clamptab = (clamptab += 256);

    for (i = 0; i < 256; i++)

	clamptab[i] = (TIFFRGBValue) i;

    _TIFFmemset(clamptab+256, 255, 2*256);	/* v > 255 => 255 */

    ycbcr->Cr_r_tab = (int*) (clamptab + 3*256);

    ycbcr->Cb_b_tab = ycbcr->Cr_r_tab + 256;

    ycbcr->Cr_g_tab = (int32*) (ycbcr->Cb_b_tab + 256);

    ycbcr->Cb_g_tab = ycbcr->Cr_g_tab + 256;

    ycbcr->Y_tab = ycbcr->Cb_g_tab + 256;

    { float f1 = 2-2*LumaRed;		int32 D1 = FIX(f1);

      float f2 = LumaRed*f1/LumaGreen;	int32 D2 = -FIX(f2);

      float f3 = 2-2*LumaBlue;		int32 D3 = FIX(f3);

      float f4 = LumaBlue*f3/LumaGreen;	int32 D4 = -FIX(f4);

      int x;

#undef LumaBlue

#undef LumaGreen

#undef LumaRed

      /*

       * i is the actual input pixel value in the range 0..255

       * Cb and Cr values are in the range -128..127 (actually

       * they are in a range defined by the ReferenceBlackWhite

       * tag) so there is some range shifting to do here when

       * constructing tables indexed by the raw pixel data.

       */

      for (i = 0, x = -128; i < 256; i++, x++) {

	    int32 Cr = (int32)Code2V(x, refBlackWhite[4] - 128.0F,

			    refBlackWhite[5] - 128.0F, 127);

	    int32 Cb = (int32)Code2V(x, refBlackWhite[2] - 128.0F,

			    refBlackWhite[3] - 128.0F, 127);

	    ycbcr->Cr_r_tab[i] = (int32)((D1*Cr + ONE_HALF)>>SHIFT);

	    ycbcr->Cb_b_tab[i] = (int32)((D3*Cb + ONE_HALF)>>SHIFT);

	    ycbcr->Cr_g_tab[i] = D2*Cr;

	    ycbcr->Cb_g_tab[i] = D4*Cb + ONE_HALF;

	    ycbcr->Y_tab[i] =

		    (int32)Code2V(x + 128, refBlackWhite[0], refBlackWhite[1], 255);

      }

    }

    return 0;

}

#undef	HICLAMP

#undef	CLAMP

#undef	Code2V

#undef	SHIFT

#undef	ONE_HALF

#undef	FIX

/* vim: set ts=8 sts=8 sw=8 noet: */

/*

 * Local Variables:

 * mode: c

 * c-basic-offset: 8

 * fill-column: 78

 * End:

 */