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