1 //////////////////////////////////////////////////////////////////////////////
2 //
3 // Copyright (c) 2004, Industrial Light & Magic, a division of Lucasfilm
4 // Entertainment Company Ltd. Portions contributed and copyright held by
5 // others as indicated. All rights reserved.
6 //
7 // Redistribution and use in source and binary forms, with or without
8 // modification, are permitted provided that the following conditions are
9 // met:
10 //
11 // * Redistributions of source code must retain the above
12 // copyright notice, this list of conditions and the following
13 // disclaimer.
14 //
15 // * Redistributions in binary form must reproduce the above
16 // copyright notice, this list of conditions and the following
17 // disclaimer in the documentation and/or other materials provided with
18 // the distribution.
19 //
20 // * Neither the name of Industrial Light & Magic nor the names of
21 // any other contributors to this software may be used to endorse or
22 // promote products derived from this software without specific prior
23 // written permission.
24 //
25 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
26 // IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
27 // THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
28 // PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
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30 // EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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34 // NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
35 // SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
36 //
37 //////////////////////////////////////////////////////////////////////////////
38
39 //-----------------------------------------------------------------------------
40 //
41 // Conversion between RGBA and YCA data.
42 //
43 //-----------------------------------------------------------------------------
44
45 #include <ImfRgbaYca.h>
46 #include <assert.h>
47 #include <algorithm>
48
49 using namespace Imath;
50 using namespace std;
51
52 namespace Imf {
53 namespace RgbaYca {
54
55
56 V3f
computeYw(const Chromaticities & cr)57 computeYw (const Chromaticities &cr)
58 {
59 M44f m = RGBtoXYZ (cr, 1);
60 return V3f (m[0][1], m[1][1], m[2][1]) / (m[0][1] + m[1][1] + m[2][1]);
61 }
62
63
64 void
RGBAtoYCA(const V3f & yw,int n,bool aIsValid,const Rgba rgbaIn[],Rgba ycaOut[])65 RGBAtoYCA (const V3f &yw,
66 int n,
67 bool aIsValid,
68 const Rgba rgbaIn[/*n*/],
69 Rgba ycaOut[/*n*/])
70 {
71 for (int i = 0; i < n; ++i)
72 {
73 Rgba in = rgbaIn[i];
74 Rgba &out = ycaOut[i];
75
76 //
77 // Conversion to YCA and subsequent chroma subsampling
78 // work only if R, G and B are finite and non-negative.
79 //
80
81 if (!in.r.isFinite() || in.r < 0)
82 in.r = 0;
83
84 if (!in.g.isFinite() || in.g < 0)
85 in.g = 0;
86
87 if (!in.b.isFinite() || in.b < 0)
88 in.b = 0;
89
90 if (in.r == in.g && in.g == in.b)
91 {
92 //
93 // Special case -- R, G and B are equal. To avoid rounding
94 // errors, we explicitly set the output luminance channel
95 // to G, and the chroma channels to 0.
96 //
97 // The special cases here and in YCAtoRGBA() ensure that
98 // converting black-and white images from RGBA to YCA and
99 // back is lossless.
100 //
101
102 out.r = 0;
103 out.g = in.g;
104 out.b = 0;
105 }
106 else
107 {
108 out.g = in.r * yw.x + in.g * yw.y + in.b * yw.z;
109
110 float Y = out.g;
111
112 if (abs (in.r - Y) < HALF_MAX * Y)
113 out.r = (in.r - Y) / Y;
114 else
115 out.r = 0;
116
117 if (abs (in.b - Y) < HALF_MAX * Y)
118 out.b = (in.b - Y) / Y;
119 else
120 out.b = 0;
121 }
122
123 if (aIsValid)
124 out.a = in.a;
125 else
126 out.a = 1;
127 }
128 }
129
130
131 void
decimateChromaHoriz(int n,const Rgba ycaIn[],Rgba ycaOut[])132 decimateChromaHoriz (int n,
133 const Rgba ycaIn[/*n+N-1*/],
134 Rgba ycaOut[/*n*/])
135 {
136 #ifdef DEBUG
137 assert (ycaIn != ycaOut);
138 #endif
139
140 int begin = N2;
141 int end = begin + n;
142
143 for (int i = begin, j = 0; i < end; ++i, ++j)
144 {
145 if ((j & 1) == 0)
146 {
147 ycaOut[j].r = ycaIn[i - 13].r * 0.001064f +
148 ycaIn[i - 11].r * -0.003771f +
149 ycaIn[i - 9].r * 0.009801f +
150 ycaIn[i - 7].r * -0.021586f +
151 ycaIn[i - 5].r * 0.043978f +
152 ycaIn[i - 3].r * -0.093067f +
153 ycaIn[i - 1].r * 0.313659f +
154 ycaIn[i ].r * 0.499846f +
155 ycaIn[i + 1].r * 0.313659f +
156 ycaIn[i + 3].r * -0.093067f +
157 ycaIn[i + 5].r * 0.043978f +
158 ycaIn[i + 7].r * -0.021586f +
159 ycaIn[i + 9].r * 0.009801f +
160 ycaIn[i + 11].r * -0.003771f +
161 ycaIn[i + 13].r * 0.001064f;
162
163 ycaOut[j].b = ycaIn[i - 13].b * 0.001064f +
164 ycaIn[i - 11].b * -0.003771f +
165 ycaIn[i - 9].b * 0.009801f +
166 ycaIn[i - 7].b * -0.021586f +
167 ycaIn[i - 5].b * 0.043978f +
168 ycaIn[i - 3].b * -0.093067f +
169 ycaIn[i - 1].b * 0.313659f +
170 ycaIn[i ].b * 0.499846f +
171 ycaIn[i + 1].b * 0.313659f +
172 ycaIn[i + 3].b * -0.093067f +
173 ycaIn[i + 5].b * 0.043978f +
174 ycaIn[i + 7].b * -0.021586f +
175 ycaIn[i + 9].b * 0.009801f +
176 ycaIn[i + 11].b * -0.003771f +
177 ycaIn[i + 13].b * 0.001064f;
178 }
179
180 ycaOut[j].g = ycaIn[i].g;
181 ycaOut[j].a = ycaIn[i].a;
182 }
183 }
184
185
186 void
decimateChromaVert(int n,const Rgba * const ycaIn[N],Rgba ycaOut[])187 decimateChromaVert (int n,
188 const Rgba * const ycaIn[N],
189 Rgba ycaOut[/*n*/])
190 {
191 for (int i = 0; i < n; ++i)
192 {
193 if ((i & 1) == 0)
194 {
195 ycaOut[i].r = ycaIn[ 0][i].r * 0.001064f +
196 ycaIn[ 2][i].r * -0.003771f +
197 ycaIn[ 4][i].r * 0.009801f +
198 ycaIn[ 6][i].r * -0.021586f +
199 ycaIn[ 8][i].r * 0.043978f +
200 ycaIn[10][i].r * -0.093067f +
201 ycaIn[12][i].r * 0.313659f +
202 ycaIn[13][i].r * 0.499846f +
203 ycaIn[14][i].r * 0.313659f +
204 ycaIn[16][i].r * -0.093067f +
205 ycaIn[18][i].r * 0.043978f +
206 ycaIn[20][i].r * -0.021586f +
207 ycaIn[22][i].r * 0.009801f +
208 ycaIn[24][i].r * -0.003771f +
209 ycaIn[26][i].r * 0.001064f;
210
211 ycaOut[i].b = ycaIn[ 0][i].b * 0.001064f +
212 ycaIn[ 2][i].b * -0.003771f +
213 ycaIn[ 4][i].b * 0.009801f +
214 ycaIn[ 6][i].b * -0.021586f +
215 ycaIn[ 8][i].b * 0.043978f +
216 ycaIn[10][i].b * -0.093067f +
217 ycaIn[12][i].b * 0.313659f +
218 ycaIn[13][i].b * 0.499846f +
219 ycaIn[14][i].b * 0.313659f +
220 ycaIn[16][i].b * -0.093067f +
221 ycaIn[18][i].b * 0.043978f +
222 ycaIn[20][i].b * -0.021586f +
223 ycaIn[22][i].b * 0.009801f +
224 ycaIn[24][i].b * -0.003771f +
225 ycaIn[26][i].b * 0.001064f;
226 }
227
228 ycaOut[i].g = ycaIn[13][i].g;
229 ycaOut[i].a = ycaIn[13][i].a;
230 }
231 }
232
233
234 void
roundYCA(int n,unsigned int roundY,unsigned int roundC,const Rgba ycaIn[],Rgba ycaOut[])235 roundYCA (int n,
236 unsigned int roundY,
237 unsigned int roundC,
238 const Rgba ycaIn[/*n*/],
239 Rgba ycaOut[/*n*/])
240 {
241 for (int i = 0; i < n; ++i)
242 {
243 ycaOut[i].g = ycaIn[i].g.round (roundY);
244 ycaOut[i].a = ycaIn[i].a;
245
246 if ((i & 1) == 0)
247 {
248 ycaOut[i].r = ycaIn[i].r.round (roundC);
249 ycaOut[i].b = ycaIn[i].b.round (roundC);
250 }
251 }
252 }
253
254
255 void
reconstructChromaHoriz(int n,const Rgba ycaIn[],Rgba ycaOut[])256 reconstructChromaHoriz (int n,
257 const Rgba ycaIn[/*n+N-1*/],
258 Rgba ycaOut[/*n*/])
259 {
260 #ifdef DEBUG
261 assert (ycaIn != ycaOut);
262 #endif
263
264 int begin = N2;
265 int end = begin + n;
266
267 for (int i = begin, j = 0; i < end; ++i, ++j)
268 {
269 if (j & 1)
270 {
271 ycaOut[j].r = ycaIn[i - 13].r * 0.002128f +
272 ycaIn[i - 11].r * -0.007540f +
273 ycaIn[i - 9].r * 0.019597f +
274 ycaIn[i - 7].r * -0.043159f +
275 ycaIn[i - 5].r * 0.087929f +
276 ycaIn[i - 3].r * -0.186077f +
277 ycaIn[i - 1].r * 0.627123f +
278 ycaIn[i + 1].r * 0.627123f +
279 ycaIn[i + 3].r * -0.186077f +
280 ycaIn[i + 5].r * 0.087929f +
281 ycaIn[i + 7].r * -0.043159f +
282 ycaIn[i + 9].r * 0.019597f +
283 ycaIn[i + 11].r * -0.007540f +
284 ycaIn[i + 13].r * 0.002128f;
285
286 ycaOut[j].b = ycaIn[i - 13].b * 0.002128f +
287 ycaIn[i - 11].b * -0.007540f +
288 ycaIn[i - 9].b * 0.019597f +
289 ycaIn[i - 7].b * -0.043159f +
290 ycaIn[i - 5].b * 0.087929f +
291 ycaIn[i - 3].b * -0.186077f +
292 ycaIn[i - 1].b * 0.627123f +
293 ycaIn[i + 1].b * 0.627123f +
294 ycaIn[i + 3].b * -0.186077f +
295 ycaIn[i + 5].b * 0.087929f +
296 ycaIn[i + 7].b * -0.043159f +
297 ycaIn[i + 9].b * 0.019597f +
298 ycaIn[i + 11].b * -0.007540f +
299 ycaIn[i + 13].b * 0.002128f;
300 }
301 else
302 {
303 ycaOut[j].r = ycaIn[i].r;
304 ycaOut[j].b = ycaIn[i].b;
305 }
306
307 ycaOut[j].g = ycaIn[i].g;
308 ycaOut[j].a = ycaIn[i].a;
309 }
310 }
311
312
313 void
reconstructChromaVert(int n,const Rgba * const ycaIn[N],Rgba ycaOut[])314 reconstructChromaVert (int n,
315 const Rgba * const ycaIn[N],
316 Rgba ycaOut[/*n*/])
317 {
318 for (int i = 0; i < n; ++i)
319 {
320 ycaOut[i].r = ycaIn[ 0][i].r * 0.002128f +
321 ycaIn[ 2][i].r * -0.007540f +
322 ycaIn[ 4][i].r * 0.019597f +
323 ycaIn[ 6][i].r * -0.043159f +
324 ycaIn[ 8][i].r * 0.087929f +
325 ycaIn[10][i].r * -0.186077f +
326 ycaIn[12][i].r * 0.627123f +
327 ycaIn[14][i].r * 0.627123f +
328 ycaIn[16][i].r * -0.186077f +
329 ycaIn[18][i].r * 0.087929f +
330 ycaIn[20][i].r * -0.043159f +
331 ycaIn[22][i].r * 0.019597f +
332 ycaIn[24][i].r * -0.007540f +
333 ycaIn[26][i].r * 0.002128f;
334
335 ycaOut[i].b = ycaIn[ 0][i].b * 0.002128f +
336 ycaIn[ 2][i].b * -0.007540f +
337 ycaIn[ 4][i].b * 0.019597f +
338 ycaIn[ 6][i].b * -0.043159f +
339 ycaIn[ 8][i].b * 0.087929f +
340 ycaIn[10][i].b * -0.186077f +
341 ycaIn[12][i].b * 0.627123f +
342 ycaIn[14][i].b * 0.627123f +
343 ycaIn[16][i].b * -0.186077f +
344 ycaIn[18][i].b * 0.087929f +
345 ycaIn[20][i].b * -0.043159f +
346 ycaIn[22][i].b * 0.019597f +
347 ycaIn[24][i].b * -0.007540f +
348 ycaIn[26][i].b * 0.002128f;
349
350 ycaOut[i].g = ycaIn[13][i].g;
351 ycaOut[i].a = ycaIn[13][i].a;
352 }
353 }
354
355
356 void
YCAtoRGBA(const Imath::V3f & yw,int n,const Rgba ycaIn[],Rgba rgbaOut[])357 YCAtoRGBA (const Imath::V3f &yw,
358 int n,
359 const Rgba ycaIn[/*n*/],
360 Rgba rgbaOut[/*n*/])
361 {
362 for (int i = 0; i < n; ++i)
363 {
364 const Rgba &in = ycaIn[i];
365 Rgba &out = rgbaOut[i];
366
367 if (in.r == 0 && in.b == 0)
368 {
369 //
370 // Special case -- both chroma channels are 0. To avoid
371 // rounding errors, we explicitly set the output R, G and B
372 // channels equal to the input luminance.
373 //
374 // The special cases here and in RGBAtoYCA() ensure that
375 // converting black-and white images from RGBA to YCA and
376 // back is lossless.
377 //
378
379 out.r = in.g;
380 out.g = in.g;
381 out.b = in.g;
382 out.a = in.a;
383 }
384 else
385 {
386 float Y = in.g;
387 float r = (in.r + 1) * Y;
388 float b = (in.b + 1) * Y;
389 float g = (Y - r * yw.x - b * yw.z) / yw.y;
390
391 out.r = r;
392 out.g = g;
393 out.b = b;
394 out.a = in.a;
395 }
396 }
397 }
398
399
400 namespace {
401
402 inline float
saturation(const Rgba & in)403 saturation (const Rgba &in)
404 {
405 float rgbMax = max (in.r, max (in.g, in.b));
406 float rgbMin = min (in.r, min (in.g, in.b));
407
408 if (rgbMax > 0)
409 return 1 - rgbMin / rgbMax;
410 else
411 return 0;
412 }
413
414
415 void
desaturate(const Rgba & in,float f,const V3f & yw,Rgba & out)416 desaturate (const Rgba &in, float f, const V3f &yw, Rgba &out)
417 {
418 float rgbMax = max (in.r, max (in.g, in.b));
419
420 out.r = max (float (rgbMax - (rgbMax - in.r) * f), 0.0f);
421 out.g = max (float (rgbMax - (rgbMax - in.g) * f), 0.0f);
422 out.b = max (float (rgbMax - (rgbMax - in.b) * f), 0.0f);
423 out.a = in.a;
424
425 float Yin = in.r * yw.x + in.g * yw.y + in.b * yw.z;
426 float Yout = out.r * yw.x + out.g * yw.y + out.b * yw.z;
427
428 if (Yout > 0)
429 {
430 out.r *= Yin / Yout;
431 out.g *= Yin / Yout;
432 out.b *= Yin / Yout;
433 }
434 }
435
436 } // namespace
437
438
439 void
fixSaturation(const Imath::V3f & yw,int n,const Rgba * const rgbaIn[3],Rgba rgbaOut[])440 fixSaturation (const Imath::V3f &yw,
441 int n,
442 const Rgba * const rgbaIn[3],
443 Rgba rgbaOut[/*n*/])
444 {
445 float neighborA2 = saturation (rgbaIn[0][0]);
446 float neighborA1 = neighborA2;
447
448 float neighborB2 = saturation (rgbaIn[2][0]);
449 float neighborB1 = neighborB2;
450
451 for (int i = 0; i < n; ++i)
452 {
453 float neighborA0 = neighborA1;
454 neighborA1 = neighborA2;
455
456 float neighborB0 = neighborB1;
457 neighborB1 = neighborB2;
458
459 if (i < n - 1)
460 {
461 neighborA2 = saturation (rgbaIn[0][i + 1]);
462 neighborB2 = saturation (rgbaIn[2][i + 1]);
463 }
464
465 //
466 // A0 A1 A2
467 // rgbaOut[i]
468 // B0 B1 B2
469 //
470
471 float sMean = min (1.0f, 0.25f * (neighborA0 + neighborA2 +
472 neighborB0 + neighborB2));
473
474 const Rgba &in = rgbaIn[1][i];
475 Rgba &out = rgbaOut[i];
476
477 float s = saturation (in);
478
479 if (s > sMean)
480 {
481 float sMax = min (1.0f, 1 - (1 - sMean) * 0.25f);
482
483 if (s > sMax)
484 {
485 desaturate (in, sMax / s, yw, out);
486 continue;
487 }
488 }
489
490 out = in;
491 }
492 }
493
494 } // namespace RgbaYca
495 } // namespace Imf
496