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1 /* $Id: tif_color.c,v 1.19 2010-12-14 02:22:42 faxguy Exp $ */
2 
3 /*
4  * Copyright (c) 1988-1997 Sam Leffler
5  * Copyright (c) 1991-1997 Silicon Graphics, Inc.
6  *
7  * Permission to use, copy, modify, distribute, and sell this software and
8  * its documentation for any purpose is hereby granted without fee, provided
9  * that (i) the above copyright notices and this permission notice appear in
10  * all copies of the software and related documentation, and (ii) the names of
11  * Sam Leffler and Silicon Graphics may not be used in any advertising or
12  * publicity relating to the software without the specific, prior written
13  * permission of Sam Leffler and Silicon Graphics.
14  *
15  * THE SOFTWARE IS PROVIDED "AS-IS" AND WITHOUT WARRANTY OF ANY KIND,
16  * EXPRESS, IMPLIED OR OTHERWISE, INCLUDING WITHOUT LIMITATION, ANY
17  * WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
18  *
19  * IN NO EVENT SHALL SAM LEFFLER OR SILICON GRAPHICS BE LIABLE FOR
20  * ANY SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY KIND,
21  * OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
22  * WHETHER OR NOT ADVISED OF THE POSSIBILITY OF DAMAGE, AND ON ANY THEORY OF
23  * LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
24  * OF THIS SOFTWARE.
25  */
26 
27 /*
28  * CIE L*a*b* to CIE XYZ and CIE XYZ to RGB conversion routines are taken
29  * from the VIPS library (http://www.vips.ecs.soton.ac.uk) with
30  * the permission of John Cupitt, the VIPS author.
31  */
32 
33 /*
34  * TIFF Library.
35  *
36  * Color space conversion routines.
37  */
38 
39 #include "tiffiop.h"
40 #include <math.h>
41 
42 /*
43  * Convert color value from the CIE L*a*b* 1976 space to CIE XYZ.
44  */
45 void
TIFFCIELabToXYZ(TIFFCIELabToRGB * cielab,uint32 l,int32 a,int32 b,float * X,float * Y,float * Z)46 TIFFCIELabToXYZ(TIFFCIELabToRGB *cielab, uint32 l, int32 a, int32 b,
47 		float *X, float *Y, float *Z)
48 {
49 	float L = (float)l * 100.0F / 255.0F;
50 	float cby, tmp;
51 
52 	if( L < 8.856F ) {
53 		*Y = (L * cielab->Y0) / 903.292F;
54 		cby = 7.787F * (*Y / cielab->Y0) + 16.0F / 116.0F;
55 	} else {
56 		cby = (L + 16.0F) / 116.0F;
57 		*Y = cielab->Y0 * cby * cby * cby;
58 	}
59 
60 	tmp = (float)a / 500.0F + cby;
61 	if( tmp < 0.2069F )
62 		*X = cielab->X0 * (tmp - 0.13793F) / 7.787F;
63 	else
64 		*X = cielab->X0 * tmp * tmp * tmp;
65 
66 	tmp = cby - (float)b / 200.0F;
67 	if( tmp < 0.2069F )
68 		*Z = cielab->Z0 * (tmp - 0.13793F) / 7.787F;
69 	else
70 		*Z = cielab->Z0 * tmp * tmp * tmp;
71 }
72 
73 #define RINT(R) ((uint32)((R)>0?((R)+0.5):((R)-0.5)))
74 /*
75  * Convert color value from the XYZ space to RGB.
76  */
77 void
TIFFXYZToRGB(TIFFCIELabToRGB * cielab,float X,float Y,float Z,uint32 * r,uint32 * g,uint32 * b)78 TIFFXYZToRGB(TIFFCIELabToRGB *cielab, float X, float Y, float Z,
79 	     uint32 *r, uint32 *g, uint32 *b)
80 {
81 	int i;
82 	float Yr, Yg, Yb;
83 	float *matrix = &cielab->display.d_mat[0][0];
84 
85 	/* Multiply through the matrix to get luminosity values. */
86 	Yr =  matrix[0] * X + matrix[1] * Y + matrix[2] * Z;
87 	Yg =  matrix[3] * X + matrix[4] * Y + matrix[5] * Z;
88 	Yb =  matrix[6] * X + matrix[7] * Y + matrix[8] * Z;
89 
90 	/* Clip input */
91 	Yr = TIFFmax(Yr, cielab->display.d_Y0R);
92 	Yg = TIFFmax(Yg, cielab->display.d_Y0G);
93 	Yb = TIFFmax(Yb, cielab->display.d_Y0B);
94 
95 	/* Avoid overflow in case of wrong input values */
96 	Yr = TIFFmin(Yr, cielab->display.d_YCR);
97 	Yg = TIFFmin(Yg, cielab->display.d_YCG);
98 	Yb = TIFFmin(Yb, cielab->display.d_YCB);
99 
100 	/* Turn luminosity to colour value. */
101 	i = (int)((Yr - cielab->display.d_Y0R) / cielab->rstep);
102 	i = TIFFmin(cielab->range, i);
103 	*r = RINT(cielab->Yr2r[i]);
104 
105 	i = (int)((Yg - cielab->display.d_Y0G) / cielab->gstep);
106 	i = TIFFmin(cielab->range, i);
107 	*g = RINT(cielab->Yg2g[i]);
108 
109 	i = (int)((Yb - cielab->display.d_Y0B) / cielab->bstep);
110 	i = TIFFmin(cielab->range, i);
111 	*b = RINT(cielab->Yb2b[i]);
112 
113 	/* Clip output. */
114 	*r = TIFFmin(*r, cielab->display.d_Vrwr);
115 	*g = TIFFmin(*g, cielab->display.d_Vrwg);
116 	*b = TIFFmin(*b, cielab->display.d_Vrwb);
117 }
118 #undef RINT
119 
120 /*
121  * Allocate conversion state structures and make look_up tables for
122  * the Yr,Yb,Yg <=> r,g,b conversions.
123  */
124 int
TIFFCIELabToRGBInit(TIFFCIELabToRGB * cielab,const TIFFDisplay * display,float * refWhite)125 TIFFCIELabToRGBInit(TIFFCIELabToRGB* cielab,
126 		    const TIFFDisplay *display, float *refWhite)
127 {
128 	int i;
129 	double gamma;
130 
131 	cielab->range = CIELABTORGB_TABLE_RANGE;
132 
133 	_TIFFmemcpy(&cielab->display, display, sizeof(TIFFDisplay));
134 
135 	/* Red */
136 	gamma = 1.0 / cielab->display.d_gammaR ;
137 	cielab->rstep =
138 		(cielab->display.d_YCR - cielab->display.d_Y0R)	/ cielab->range;
139 	for(i = 0; i <= cielab->range; i++) {
140 		cielab->Yr2r[i] = cielab->display.d_Vrwr
141 		    * ((float)pow((double)i / cielab->range, gamma));
142 	}
143 
144 	/* Green */
145 	gamma = 1.0 / cielab->display.d_gammaG ;
146 	cielab->gstep =
147 	    (cielab->display.d_YCR - cielab->display.d_Y0R) / cielab->range;
148 	for(i = 0; i <= cielab->range; i++) {
149 		cielab->Yg2g[i] = cielab->display.d_Vrwg
150 		    * ((float)pow((double)i / cielab->range, gamma));
151 	}
152 
153 	/* Blue */
154 	gamma = 1.0 / cielab->display.d_gammaB ;
155 	cielab->bstep =
156 	    (cielab->display.d_YCR - cielab->display.d_Y0R) / cielab->range;
157 	for(i = 0; i <= cielab->range; i++) {
158 		cielab->Yb2b[i] = cielab->display.d_Vrwb
159 		    * ((float)pow((double)i / cielab->range, gamma));
160 	}
161 
162 	/* Init reference white point */
163 	cielab->X0 = refWhite[0];
164 	cielab->Y0 = refWhite[1];
165 	cielab->Z0 = refWhite[2];
166 
167 	return 0;
168 }
169 
170 /*
171  * Convert color value from the YCbCr space to CIE XYZ.
172  * The colorspace conversion algorithm comes from the IJG v5a code;
173  * see below for more information on how it works.
174  */
175 #define	SHIFT			16
176 #define	FIX(x)			((int32)((x) * (1L<<SHIFT) + 0.5))
177 #define	ONE_HALF		((int32)(1<<(SHIFT-1)))
178 #define	Code2V(c, RB, RW, CR)	((((c)-(int32)(RB))*(float)(CR))/(float)(((RW)-(RB)) ? ((RW)-(RB)) : 1))
179 #define	CLAMP(f,min,max)	((f)<(min)?(min):(f)>(max)?(max):(f))
180 #define HICLAMP(f,max)		((f)>(max)?(max):(f))
181 
182 void
TIFFYCbCrtoRGB(TIFFYCbCrToRGB * ycbcr,uint32 Y,int32 Cb,int32 Cr,uint32 * r,uint32 * g,uint32 * b)183 TIFFYCbCrtoRGB(TIFFYCbCrToRGB *ycbcr, uint32 Y, int32 Cb, int32 Cr,
184 	       uint32 *r, uint32 *g, uint32 *b)
185 {
186 	int32 i;
187 
188 	/* XXX: Only 8-bit YCbCr input supported for now */
189 	Y = HICLAMP(Y, 255), Cb = CLAMP(Cb, 0, 255), Cr = CLAMP(Cr, 0, 255);
190 
191 	i = ycbcr->Y_tab[Y] + ycbcr->Cr_r_tab[Cr];
192 	*r = CLAMP(i, 0, 255);
193 	i = ycbcr->Y_tab[Y]
194 	    + (int)((ycbcr->Cb_g_tab[Cb] + ycbcr->Cr_g_tab[Cr]) >> SHIFT);
195 	*g = CLAMP(i, 0, 255);
196 	i = ycbcr->Y_tab[Y] + ycbcr->Cb_b_tab[Cb];
197 	*b = CLAMP(i, 0, 255);
198 }
199 
200 /*
201  * Initialize the YCbCr->RGB conversion tables.  The conversion
202  * is done according to the 6.0 spec:
203  *
204  *    R = Y + Cr*(2 - 2*LumaRed)
205  *    B = Y + Cb*(2 - 2*LumaBlue)
206  *    G =   Y
207  *        - LumaBlue*Cb*(2-2*LumaBlue)/LumaGreen
208  *        - LumaRed*Cr*(2-2*LumaRed)/LumaGreen
209  *
210  * To avoid floating point arithmetic the fractional constants that
211  * come out of the equations are represented as fixed point values
212  * in the range 0...2^16.  We also eliminate multiplications by
213  * pre-calculating possible values indexed by Cb and Cr (this code
214  * assumes conversion is being done for 8-bit samples).
215  */
216 int
TIFFYCbCrToRGBInit(TIFFYCbCrToRGB * ycbcr,float * luma,float * refBlackWhite)217 TIFFYCbCrToRGBInit(TIFFYCbCrToRGB* ycbcr, float *luma, float *refBlackWhite)
218 {
219     TIFFRGBValue* clamptab;
220     int i;
221 
222 #define LumaRed	    luma[0]
223 #define LumaGreen   luma[1]
224 #define LumaBlue    luma[2]
225 
226     clamptab = (TIFFRGBValue*)(
227 	(uint8*) ycbcr+TIFFroundup_32(sizeof (TIFFYCbCrToRGB), sizeof (long)));
228     _TIFFmemset(clamptab, 0, 256);		/* v < 0 => 0 */
229     ycbcr->clamptab = (clamptab += 256);
230     for (i = 0; i < 256; i++)
231 	clamptab[i] = (TIFFRGBValue) i;
232     _TIFFmemset(clamptab+256, 255, 2*256);	/* v > 255 => 255 */
233     ycbcr->Cr_r_tab = (int*) (clamptab + 3*256);
234     ycbcr->Cb_b_tab = ycbcr->Cr_r_tab + 256;
235     ycbcr->Cr_g_tab = (int32*) (ycbcr->Cb_b_tab + 256);
236     ycbcr->Cb_g_tab = ycbcr->Cr_g_tab + 256;
237     ycbcr->Y_tab = ycbcr->Cb_g_tab + 256;
238 
239     { float f1 = 2-2*LumaRed;		int32 D1 = FIX(f1);
240       float f2 = LumaRed*f1/LumaGreen;	int32 D2 = -FIX(f2);
241       float f3 = 2-2*LumaBlue;		int32 D3 = FIX(f3);
242       float f4 = LumaBlue*f3/LumaGreen;	int32 D4 = -FIX(f4);
243       int x;
244 
245 #undef LumaBlue
246 #undef LumaGreen
247 #undef LumaRed
248 
249       /*
250        * i is the actual input pixel value in the range 0..255
251        * Cb and Cr values are in the range -128..127 (actually
252        * they are in a range defined by the ReferenceBlackWhite
253        * tag) so there is some range shifting to do here when
254        * constructing tables indexed by the raw pixel data.
255        */
256       for (i = 0, x = -128; i < 256; i++, x++) {
257 	    int32 Cr = (int32)Code2V(x, refBlackWhite[4] - 128.0F,
258 			    refBlackWhite[5] - 128.0F, 127);
259 	    int32 Cb = (int32)Code2V(x, refBlackWhite[2] - 128.0F,
260 			    refBlackWhite[3] - 128.0F, 127);
261 
262 	    ycbcr->Cr_r_tab[i] = (int32)((D1*Cr + ONE_HALF)>>SHIFT);
263 	    ycbcr->Cb_b_tab[i] = (int32)((D3*Cb + ONE_HALF)>>SHIFT);
264 	    ycbcr->Cr_g_tab[i] = D2*Cr;
265 	    ycbcr->Cb_g_tab[i] = D4*Cb + ONE_HALF;
266 	    ycbcr->Y_tab[i] =
267 		    (int32)Code2V(x + 128, refBlackWhite[0], refBlackWhite[1], 255);
268       }
269     }
270 
271     return 0;
272 }
273 #undef	HICLAMP
274 #undef	CLAMP
275 #undef	Code2V
276 #undef	SHIFT
277 #undef	ONE_HALF
278 #undef	FIX
279 
280 /* vim: set ts=8 sts=8 sw=8 noet: */
281 /*
282  * Local Variables:
283  * mode: c
284  * c-basic-offset: 8
285  * fill-column: 78
286  * End:
287  */
288