1 /*
2 * Copyright (c) 1988-1997 Sam Leffler
3 * Copyright (c) 1991-1997 Silicon Graphics, Inc.
4 *
5 * Permission to use, copy, modify, distribute, and sell this software and
6 * its documentation for any purpose is hereby granted without fee, provided
7 * that (i) the above copyright notices and this permission notice appear in
8 * all copies of the software and related documentation, and (ii) the names of
9 * Sam Leffler and Silicon Graphics may not be used in any advertising or
10 * publicity relating to the software without the specific, prior written
11 * permission of Sam Leffler and Silicon Graphics.
12 *
13 * THE SOFTWARE IS PROVIDED "AS-IS" AND WITHOUT WARRANTY OF ANY KIND,
14 * EXPRESS, IMPLIED OR OTHERWISE, INCLUDING WITHOUT LIMITATION, ANY
15 * WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
16 *
17 * IN NO EVENT SHALL SAM LEFFLER OR SILICON GRAPHICS BE LIABLE FOR
18 * ANY SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY KIND,
19 * OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
20 * WHETHER OR NOT ADVISED OF THE POSSIBILITY OF DAMAGE, AND ON ANY THEORY OF
21 * LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
22 * OF THIS SOFTWARE.
23 */
24
25 /*
26 * CIE L*a*b* to CIE XYZ and CIE XYZ to RGB conversion routines are taken
27 * from the VIPS library (http://www.vips.ecs.soton.ac.uk) with
28 * the permission of John Cupitt, the VIPS author.
29 */
30
31 /*
32 * TIFF Library.
33 *
34 * Color space conversion routines.
35 */
36
37 #include "tiffiop.h"
38 #include <math.h>
39
40 /*
41 * Convert color value from the CIE L*a*b* 1976 space to CIE XYZ.
42 */
TIFFCIELabToXYZ(TIFFCIELabToRGB * cielab,uint32_t l,int32_t a,int32_t b,float * X,float * Y,float * Z)43 void TIFFCIELabToXYZ(TIFFCIELabToRGB *cielab, uint32_t l, int32_t a, int32_t b,
44 float *X, float *Y, float *Z)
45 {
46 TIFFCIELab16ToXYZ(cielab, l * 257, a * 256, b * 256, X, Y, Z);
47 }
48
49 /*
50 * For CIELab encoded in 16 bits, L is an unsigned integer range [0,65535].
51 * The a* and b* components are signed integers range [-32768,32767]. The 16
52 * bit chrominance values are encoded as 256 times the 1976 CIE a* and b*
53 * values
54 */
TIFFCIELab16ToXYZ(TIFFCIELabToRGB * cielab,uint32_t l,int32_t a,int32_t b,float * X,float * Y,float * Z)55 void TIFFCIELab16ToXYZ(TIFFCIELabToRGB *cielab, uint32_t l, int32_t a,
56 int32_t b, float *X, float *Y, float *Z)
57 {
58 float L = (float)l * 100.0F / 65535.0F;
59 float cby, tmp;
60
61 if (L < 8.856F)
62 {
63 *Y = (L * cielab->Y0) / 903.292F;
64 cby = 7.787F * (*Y / cielab->Y0) + 16.0F / 116.0F;
65 }
66 else
67 {
68 cby = (L + 16.0F) / 116.0F;
69 *Y = cielab->Y0 * cby * cby * cby;
70 }
71
72 tmp = (float)a / 256.0F / 500.0F + cby;
73 if (tmp < 0.2069F)
74 *X = cielab->X0 * (tmp - 0.13793F) / 7.787F;
75 else
76 *X = cielab->X0 * tmp * tmp * tmp;
77
78 tmp = cby - (float)b / 256.0F / 200.0F;
79 if (tmp < 0.2069F)
80 *Z = cielab->Z0 * (tmp - 0.13793F) / 7.787F;
81 else
82 *Z = cielab->Z0 * tmp * tmp * tmp;
83 }
84
85 #define RINT(R) ((uint32_t)((R) > 0 ? ((R) + 0.5) : ((R)-0.5)))
86 /*
87 * Convert color value from the XYZ space to RGB.
88 */
TIFFXYZToRGB(TIFFCIELabToRGB * cielab,float X,float Y,float Z,uint32_t * r,uint32_t * g,uint32_t * b)89 void TIFFXYZToRGB(TIFFCIELabToRGB *cielab, float X, float Y, float Z,
90 uint32_t *r, uint32_t *g, uint32_t *b)
91 {
92 int i;
93 float Yr, Yg, Yb;
94 float *matrix = &cielab->display.d_mat[0][0];
95
96 /* Multiply through the matrix to get luminosity values. */
97 Yr = matrix[0] * X + matrix[1] * Y + matrix[2] * Z;
98 Yg = matrix[3] * X + matrix[4] * Y + matrix[5] * Z;
99 Yb = matrix[6] * X + matrix[7] * Y + matrix[8] * Z;
100
101 /* Clip input */
102 Yr = TIFFmax(Yr, cielab->display.d_Y0R);
103 Yg = TIFFmax(Yg, cielab->display.d_Y0G);
104 Yb = TIFFmax(Yb, cielab->display.d_Y0B);
105
106 /* Avoid overflow in case of wrong input values */
107 Yr = TIFFmin(Yr, cielab->display.d_YCR);
108 Yg = TIFFmin(Yg, cielab->display.d_YCG);
109 Yb = TIFFmin(Yb, cielab->display.d_YCB);
110
111 /* Turn luminosity to colour value. */
112 i = (int)((Yr - cielab->display.d_Y0R) / cielab->rstep);
113 i = TIFFmin(cielab->range, i);
114 *r = RINT(cielab->Yr2r[i]);
115
116 i = (int)((Yg - cielab->display.d_Y0G) / cielab->gstep);
117 i = TIFFmin(cielab->range, i);
118 *g = RINT(cielab->Yg2g[i]);
119
120 i = (int)((Yb - cielab->display.d_Y0B) / cielab->bstep);
121 i = TIFFmin(cielab->range, i);
122 *b = RINT(cielab->Yb2b[i]);
123
124 /* Clip output. */
125 *r = TIFFmin(*r, cielab->display.d_Vrwr);
126 *g = TIFFmin(*g, cielab->display.d_Vrwg);
127 *b = TIFFmin(*b, cielab->display.d_Vrwb);
128 }
129 #undef RINT
130
131 /*
132 * Allocate conversion state structures and make look_up tables for
133 * the Yr,Yb,Yg <=> r,g,b conversions.
134 */
TIFFCIELabToRGBInit(TIFFCIELabToRGB * cielab,const TIFFDisplay * display,float * refWhite)135 int TIFFCIELabToRGBInit(TIFFCIELabToRGB *cielab, const TIFFDisplay *display,
136 float *refWhite)
137 {
138 int i;
139 double dfGamma;
140
141 cielab->range = CIELABTORGB_TABLE_RANGE;
142
143 _TIFFmemcpy(&cielab->display, display, sizeof(TIFFDisplay));
144
145 /* Red */
146 dfGamma = 1.0 / cielab->display.d_gammaR;
147 cielab->rstep =
148 (cielab->display.d_YCR - cielab->display.d_Y0R) / cielab->range;
149 for (i = 0; i <= cielab->range; i++)
150 {
151 cielab->Yr2r[i] = cielab->display.d_Vrwr *
152 ((float)pow((double)i / cielab->range, dfGamma));
153 }
154
155 /* Green */
156 dfGamma = 1.0 / cielab->display.d_gammaG;
157 cielab->gstep =
158 (cielab->display.d_YCR - cielab->display.d_Y0R) / cielab->range;
159 for (i = 0; i <= cielab->range; i++)
160 {
161 cielab->Yg2g[i] = cielab->display.d_Vrwg *
162 ((float)pow((double)i / cielab->range, dfGamma));
163 }
164
165 /* Blue */
166 dfGamma = 1.0 / cielab->display.d_gammaB;
167 cielab->bstep =
168 (cielab->display.d_YCR - cielab->display.d_Y0R) / cielab->range;
169 for (i = 0; i <= cielab->range; i++)
170 {
171 cielab->Yb2b[i] = cielab->display.d_Vrwb *
172 ((float)pow((double)i / cielab->range, dfGamma));
173 }
174
175 /* Init reference white point */
176 cielab->X0 = refWhite[0];
177 cielab->Y0 = refWhite[1];
178 cielab->Z0 = refWhite[2];
179
180 return 0;
181 }
182
183 /*
184 * Convert color value from the YCbCr space to RGB.
185 * The colorspace conversion algorithm comes from the IJG v5a code;
186 * see below for more information on how it works.
187 */
188 #define SHIFT 16
189 #define FIX(x) ((int32_t)((x) * (1L << SHIFT) + 0.5))
190 #define ONE_HALF ((int32_t)(1 << (SHIFT - 1)))
191 #define Code2V(c, RB, RW, CR) \
192 ((((c) - (int32_t)(RB)) * (float)(CR)) / \
193 (float)(((RW) - (RB) != 0) ? ((RW) - (RB)) : 1))
194 /* !((f)>=(min)) written that way to deal with NaN */
195 #define CLAMP(f, min, max) \
196 ((!((f) >= (min))) ? (min) : (f) > (max) ? (max) : (f))
197 #define HICLAMP(f, max) ((f) > (max) ? (max) : (f))
198
TIFFYCbCrtoRGB(TIFFYCbCrToRGB * ycbcr,uint32_t Y,int32_t Cb,int32_t Cr,uint32_t * r,uint32_t * g,uint32_t * b)199 void TIFFYCbCrtoRGB(TIFFYCbCrToRGB *ycbcr, uint32_t Y, int32_t Cb, int32_t Cr,
200 uint32_t *r, uint32_t *g, uint32_t *b)
201 {
202 int32_t i;
203
204 /* XXX: Only 8-bit YCbCr input supported for now */
205 Y = HICLAMP(Y, 255);
206 Cb = CLAMP(Cb, 0, 255);
207 Cr = CLAMP(Cr, 0, 255);
208
209 i = ycbcr->Y_tab[Y] + ycbcr->Cr_r_tab[Cr];
210 *r = CLAMP(i, 0, 255);
211 i = ycbcr->Y_tab[Y] +
212 (int)((ycbcr->Cb_g_tab[Cb] + ycbcr->Cr_g_tab[Cr]) >> SHIFT);
213 *g = CLAMP(i, 0, 255);
214 i = ycbcr->Y_tab[Y] + ycbcr->Cb_b_tab[Cb];
215 *b = CLAMP(i, 0, 255);
216 }
217
218 /* Clamp function for sanitization purposes. Normally clamping should not */
219 /* occur for well behaved chroma and refBlackWhite coefficients */
CLAMPw(float v,float vmin,float vmax)220 static float CLAMPw(float v, float vmin, float vmax)
221 {
222 if (v < vmin)
223 {
224 /* printf("%f clamped to %f\n", v, vmin); */
225 return vmin;
226 }
227 if (v > vmax)
228 {
229 /* printf("%f clamped to %f\n", v, vmax); */
230 return vmax;
231 }
232 return v;
233 }
234
235 /*
236 * Initialize the YCbCr->RGB conversion tables. The conversion
237 * is done according to the 6.0 spec:
238 *
239 * R = Y + Cr*(2 - 2*LumaRed)
240 * B = Y + Cb*(2 - 2*LumaBlue)
241 * G = Y
242 * - LumaBlue*Cb*(2-2*LumaBlue)/LumaGreen
243 * - LumaRed*Cr*(2-2*LumaRed)/LumaGreen
244 *
245 * To avoid floating point arithmetic the fractional constants that
246 * come out of the equations are represented as fixed point values
247 * in the range 0...2^16. We also eliminate multiplications by
248 * pre-calculating possible values indexed by Cb and Cr (this code
249 * assumes conversion is being done for 8-bit samples).
250 */
TIFFYCbCrToRGBInit(TIFFYCbCrToRGB * ycbcr,float * luma,float * refBlackWhite)251 int TIFFYCbCrToRGBInit(TIFFYCbCrToRGB *ycbcr, float *luma, float *refBlackWhite)
252 {
253 TIFFRGBValue *clamptab;
254 int i;
255
256 #define LumaRed luma[0]
257 #define LumaGreen luma[1]
258 #define LumaBlue luma[2]
259
260 clamptab =
261 (TIFFRGBValue *)((uint8_t *)ycbcr +
262 TIFFroundup_32(sizeof(TIFFYCbCrToRGB), sizeof(long)));
263 _TIFFmemset(clamptab, 0, 256); /* v < 0 => 0 */
264 ycbcr->clamptab = (clamptab += 256);
265 for (i = 0; i < 256; i++)
266 clamptab[i] = (TIFFRGBValue)i;
267 _TIFFmemset(clamptab + 256, 255, 2 * 256); /* v > 255 => 255 */
268 ycbcr->Cr_r_tab = (int *)(clamptab + 3 * 256);
269 ycbcr->Cb_b_tab = ycbcr->Cr_r_tab + 256;
270 ycbcr->Cr_g_tab = (int32_t *)(ycbcr->Cb_b_tab + 256);
271 ycbcr->Cb_g_tab = ycbcr->Cr_g_tab + 256;
272 ycbcr->Y_tab = ycbcr->Cb_g_tab + 256;
273
274 {
275 float f1 = 2 - 2 * LumaRed;
276 int32_t D1 = FIX(CLAMP(f1, 0.0F, 2.0F));
277 float f2 = LumaRed * f1 / LumaGreen;
278 int32_t D2 = -FIX(CLAMP(f2, 0.0F, 2.0F));
279 float f3 = 2 - 2 * LumaBlue;
280 int32_t D3 = FIX(CLAMP(f3, 0.0F, 2.0F));
281 float f4 = LumaBlue * f3 / LumaGreen;
282 int32_t D4 = -FIX(CLAMP(f4, 0.0F, 2.0F));
283 int x;
284
285 #undef LumaBlue
286 #undef LumaGreen
287 #undef LumaRed
288
289 /*
290 * i is the actual input pixel value in the range 0..255
291 * Cb and Cr values are in the range -128..127 (actually
292 * they are in a range defined by the ReferenceBlackWhite
293 * tag) so there is some range shifting to do here when
294 * constructing tables indexed by the raw pixel data.
295 */
296 for (i = 0, x = -128; i < 256; i++, x++)
297 {
298 int32_t Cr = (int32_t)CLAMPw(Code2V(x, refBlackWhite[4] - 128.0F,
299 refBlackWhite[5] - 128.0F, 127),
300 -128.0F * 32, 128.0F * 32);
301 int32_t Cb = (int32_t)CLAMPw(Code2V(x, refBlackWhite[2] - 128.0F,
302 refBlackWhite[3] - 128.0F, 127),
303 -128.0F * 32, 128.0F * 32);
304
305 ycbcr->Cr_r_tab[i] = (int32_t)((D1 * Cr + ONE_HALF) >> SHIFT);
306 ycbcr->Cb_b_tab[i] = (int32_t)((D3 * Cb + ONE_HALF) >> SHIFT);
307 ycbcr->Cr_g_tab[i] = D2 * Cr;
308 ycbcr->Cb_g_tab[i] = D4 * Cb + ONE_HALF;
309 ycbcr->Y_tab[i] = (int32_t)CLAMPw(
310 Code2V(x + 128, refBlackWhite[0], refBlackWhite[1], 255),
311 -128.0F * 32, 128.0F * 32);
312 }
313 }
314
315 return 0;
316 }
317 #undef HICLAMP
318 #undef CLAMP
319 #undef Code2V
320 #undef SHIFT
321 #undef ONE_HALF
322 #undef FIX
323