1 /* 2 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 3 * 4 * This code is free software; you can redistribute it and/or modify it 5 * under the terms of the GNU General Public License version 2 only, as 6 * published by the Free Software Foundation. Oracle designates this 7 * particular file as subject to the "Classpath" exception as provided 8 * by Oracle in the LICENSE file that accompanied this code. 9 * 10 * This code is distributed in the hope that it will be useful, but WITHOUT 11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 12 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 13 * version 2 for more details (a copy is included in the LICENSE file that 14 * accompanied this code). 15 * 16 * You should have received a copy of the GNU General Public License version 17 * 2 along with this work; if not, write to the Free Software Foundation, 18 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 19 * 20 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 21 * or visit www.oracle.com if you need additional information or have any 22 * questions. 23 */ 24 25 // This file is available under and governed by the GNU General Public 26 // License version 2 only, as published by the Free Software Foundation. 27 // However, the following notice accompanied the original version of this 28 // file: 29 // 30 //--------------------------------------------------------------------------------- 31 // 32 // Little Color Management System 33 // Copyright (c) 1998-2013 Marti Maria Saguer 34 // 35 // Permission is hereby granted, free of charge, to any person obtaining 36 // a copy of this software and associated documentation files (the "Software"), 37 // to deal in the Software without restriction, including without limitation 38 // the rights to use, copy, modify, merge, publish, distribute, sublicense, 39 // and/or sell copies of the Software, and to permit persons to whom the Software 40 // is furnished to do so, subject to the following conditions: 41 // 42 // The above copyright notice and this permission notice shall be included in 43 // all copies or substantial portions of the Software. 44 // 45 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, 46 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO 47 // THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND 48 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE 49 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION 50 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION 51 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. 52 // 53 //--------------------------------------------------------------------------------- 54 // 55 #include "lcms2_internal.h" 56 57 // Tone curves are powerful constructs that can contain curves specified in diverse ways. 58 // The curve is stored in segments, where each segment can be sampled or specified by parameters. 59 // a 16.bit simplification of the *whole* curve is kept for optimization purposes. For float operation, 60 // each segment is evaluated separately. Plug-ins may be used to define new parametric schemes, 61 // each plug-in may define up to MAX_TYPES_IN_LCMS_PLUGIN functions types. For defining a function, 62 // the plug-in should provide the type id, how many parameters each type has, and a pointer to 63 // a procedure that evaluates the function. In the case of reverse evaluation, the evaluator will 64 // be called with the type id as a negative value, and a sampled version of the reversed curve 65 // will be built. 66 67 // ----------------------------------------------------------------- Implementation 68 // Maxim number of nodes 69 #define MAX_NODES_IN_CURVE 4097 70 #define MINUS_INF (-1E22F) 71 #define PLUS_INF (+1E22F) 72 73 // The list of supported parametric curves 74 typedef struct _cmsParametricCurvesCollection_st { 75 76 cmsUInt32Number nFunctions; // Number of supported functions in this chunk 77 cmsInt32Number FunctionTypes[MAX_TYPES_IN_LCMS_PLUGIN]; // The identification types 78 cmsUInt32Number ParameterCount[MAX_TYPES_IN_LCMS_PLUGIN]; // Number of parameters for each function 79 80 cmsParametricCurveEvaluator Evaluator; // The evaluator 81 82 struct _cmsParametricCurvesCollection_st* Next; // Next in list 83 84 } _cmsParametricCurvesCollection; 85 86 // This is the default (built-in) evaluator 87 static cmsFloat64Number DefaultEvalParametricFn(cmsInt32Number Type, const cmsFloat64Number Params[], cmsFloat64Number R); 88 89 // The built-in list 90 static _cmsParametricCurvesCollection DefaultCurves = { 91 9, // # of curve types 92 { 1, 2, 3, 4, 5, 6, 7, 8, 108 }, // Parametric curve ID 93 { 1, 3, 4, 5, 7, 4, 5, 5, 1 }, // Parameters by type 94 DefaultEvalParametricFn, // Evaluator 95 NULL // Next in chain 96 }; 97 98 // Duplicates the zone of memory used by the plug-in in the new context 99 static 100 void DupPluginCurvesList(struct _cmsContext_struct* ctx, 101 const struct _cmsContext_struct* src) 102 { 103 _cmsCurvesPluginChunkType newHead = { NULL }; 104 _cmsParametricCurvesCollection* entry; 105 _cmsParametricCurvesCollection* Anterior = NULL; 106 _cmsCurvesPluginChunkType* head = (_cmsCurvesPluginChunkType*) src->chunks[CurvesPlugin]; 107 108 _cmsAssert(head != NULL); 109 110 // Walk the list copying all nodes 111 for (entry = head->ParametricCurves; 112 entry != NULL; 113 entry = entry ->Next) { 114 115 _cmsParametricCurvesCollection *newEntry = ( _cmsParametricCurvesCollection *) _cmsSubAllocDup(ctx ->MemPool, entry, sizeof(_cmsParametricCurvesCollection)); 116 117 if (newEntry == NULL) 118 return; 119 120 // We want to keep the linked list order, so this is a little bit tricky 121 newEntry -> Next = NULL; 122 if (Anterior) 123 Anterior -> Next = newEntry; 124 125 Anterior = newEntry; 126 127 if (newHead.ParametricCurves == NULL) 128 newHead.ParametricCurves = newEntry; 129 } 130 131 ctx ->chunks[CurvesPlugin] = _cmsSubAllocDup(ctx->MemPool, &newHead, sizeof(_cmsCurvesPluginChunkType)); 132 } 133 134 // The allocator have to follow the chain 135 void _cmsAllocCurvesPluginChunk(struct _cmsContext_struct* ctx, 136 const struct _cmsContext_struct* src) 137 { 138 _cmsAssert(ctx != NULL); 139 140 if (src != NULL) { 141 142 // Copy all linked list 143 DupPluginCurvesList(ctx, src); 144 } 145 else { 146 static _cmsCurvesPluginChunkType CurvesPluginChunk = { NULL }; 147 ctx ->chunks[CurvesPlugin] = _cmsSubAllocDup(ctx ->MemPool, &CurvesPluginChunk, sizeof(_cmsCurvesPluginChunkType)); 148 } 149 } 150 151 152 // The linked list head 153 _cmsCurvesPluginChunkType _cmsCurvesPluginChunk = { NULL }; 154 155 // As a way to install new parametric curves 156 cmsBool _cmsRegisterParametricCurvesPlugin(cmsContext ContextID, cmsPluginBase* Data) 157 { 158 _cmsCurvesPluginChunkType* ctx = ( _cmsCurvesPluginChunkType*) _cmsContextGetClientChunk(ContextID, CurvesPlugin); 159 cmsPluginParametricCurves* Plugin = (cmsPluginParametricCurves*) Data; 160 _cmsParametricCurvesCollection* fl; 161 162 if (Data == NULL) { 163 164 ctx -> ParametricCurves = NULL; 165 return TRUE; 166 } 167 168 fl = (_cmsParametricCurvesCollection*) _cmsPluginMalloc(ContextID, sizeof(_cmsParametricCurvesCollection)); 169 if (fl == NULL) return FALSE; 170 171 // Copy the parameters 172 fl ->Evaluator = Plugin ->Evaluator; 173 fl ->nFunctions = Plugin ->nFunctions; 174 175 // Make sure no mem overwrites 176 if (fl ->nFunctions > MAX_TYPES_IN_LCMS_PLUGIN) 177 fl ->nFunctions = MAX_TYPES_IN_LCMS_PLUGIN; 178 179 // Copy the data 180 memmove(fl->FunctionTypes, Plugin ->FunctionTypes, fl->nFunctions * sizeof(cmsUInt32Number)); 181 memmove(fl->ParameterCount, Plugin ->ParameterCount, fl->nFunctions * sizeof(cmsUInt32Number)); 182 183 // Keep linked list 184 fl ->Next = ctx->ParametricCurves; 185 ctx->ParametricCurves = fl; 186 187 // All is ok 188 return TRUE; 189 } 190 191 192 // Search in type list, return position or -1 if not found 193 static 194 int IsInSet(int Type, _cmsParametricCurvesCollection* c) 195 { 196 int i; 197 198 for (i=0; i < (int) c ->nFunctions; i++) 199 if (abs(Type) == c ->FunctionTypes[i]) return i; 200 201 return -1; 202 } 203 204 205 // Search for the collection which contains a specific type 206 static 207 _cmsParametricCurvesCollection *GetParametricCurveByType(cmsContext ContextID, int Type, int* index) 208 { 209 _cmsParametricCurvesCollection* c; 210 int Position; 211 _cmsCurvesPluginChunkType* ctx = ( _cmsCurvesPluginChunkType*) _cmsContextGetClientChunk(ContextID, CurvesPlugin); 212 213 for (c = ctx->ParametricCurves; c != NULL; c = c ->Next) { 214 215 Position = IsInSet(Type, c); 216 217 if (Position != -1) { 218 if (index != NULL) 219 *index = Position; 220 return c; 221 } 222 } 223 // If none found, revert for defaults 224 for (c = &DefaultCurves; c != NULL; c = c ->Next) { 225 226 Position = IsInSet(Type, c); 227 228 if (Position != -1) { 229 if (index != NULL) 230 *index = Position; 231 return c; 232 } 233 } 234 235 return NULL; 236 } 237 238 // Low level allocate, which takes care of memory details. nEntries may be zero, and in this case 239 // no optimation curve is computed. nSegments may also be zero in the inverse case, where only the 240 // optimization curve is given. Both features simultaneously is an error 241 static 242 cmsToneCurve* AllocateToneCurveStruct(cmsContext ContextID, cmsUInt32Number nEntries, 243 cmsUInt32Number nSegments, const cmsCurveSegment* Segments, 244 const cmsUInt16Number* Values) 245 { 246 cmsToneCurve* p; 247 cmsUInt32Number i; 248 249 // We allow huge tables, which are then restricted for smoothing operations 250 if (nEntries > 65530) { 251 cmsSignalError(ContextID, cmsERROR_RANGE, "Couldn't create tone curve of more than 65530 entries"); 252 return NULL; 253 } 254 255 if (nEntries == 0 && nSegments == 0) { 256 cmsSignalError(ContextID, cmsERROR_RANGE, "Couldn't create tone curve with zero segments and no table"); 257 return NULL; 258 } 259 260 // Allocate all required pointers, etc. 261 p = (cmsToneCurve*) _cmsMallocZero(ContextID, sizeof(cmsToneCurve)); 262 if (!p) return NULL; 263 264 // In this case, there are no segments 265 if (nSegments == 0) { 266 p ->Segments = NULL; 267 p ->Evals = NULL; 268 } 269 else { 270 p ->Segments = (cmsCurveSegment*) _cmsCalloc(ContextID, nSegments, sizeof(cmsCurveSegment)); 271 if (p ->Segments == NULL) goto Error; 272 273 p ->Evals = (cmsParametricCurveEvaluator*) _cmsCalloc(ContextID, nSegments, sizeof(cmsParametricCurveEvaluator)); 274 if (p ->Evals == NULL) goto Error; 275 } 276 277 p -> nSegments = nSegments; 278 279 // This 16-bit table contains a limited precision representation of the whole curve and is kept for 280 // increasing xput on certain operations. 281 if (nEntries == 0) { 282 p ->Table16 = NULL; 283 } 284 else { 285 p ->Table16 = (cmsUInt16Number*) _cmsCalloc(ContextID, nEntries, sizeof(cmsUInt16Number)); 286 if (p ->Table16 == NULL) goto Error; 287 } 288 289 p -> nEntries = nEntries; 290 291 // Initialize members if requested 292 if (Values != NULL && (nEntries > 0)) { 293 294 for (i=0; i < nEntries; i++) 295 p ->Table16[i] = Values[i]; 296 } 297 298 // Initialize the segments stuff. The evaluator for each segment is located and a pointer to it 299 // is placed in advance to maximize performance. 300 if (Segments != NULL && (nSegments > 0)) { 301 302 _cmsParametricCurvesCollection *c; 303 304 p ->SegInterp = (cmsInterpParams**) _cmsCalloc(ContextID, nSegments, sizeof(cmsInterpParams*)); 305 if (p ->SegInterp == NULL) goto Error; 306 307 for (i=0; i < nSegments; i++) { 308 309 // Type 0 is a special marker for table-based curves 310 if (Segments[i].Type == 0) 311 p ->SegInterp[i] = _cmsComputeInterpParams(ContextID, Segments[i].nGridPoints, 1, 1, NULL, CMS_LERP_FLAGS_FLOAT); 312 313 memmove(&p ->Segments[i], &Segments[i], sizeof(cmsCurveSegment)); 314 315 if (Segments[i].Type == 0 && Segments[i].SampledPoints != NULL) 316 p ->Segments[i].SampledPoints = (cmsFloat32Number*) _cmsDupMem(ContextID, Segments[i].SampledPoints, sizeof(cmsFloat32Number) * Segments[i].nGridPoints); 317 else 318 p ->Segments[i].SampledPoints = NULL; 319 320 321 c = GetParametricCurveByType(ContextID, Segments[i].Type, NULL); 322 if (c != NULL) 323 p ->Evals[i] = c ->Evaluator; 324 } 325 } 326 327 p ->InterpParams = _cmsComputeInterpParams(ContextID, p ->nEntries, 1, 1, p->Table16, CMS_LERP_FLAGS_16BITS); 328 if (p->InterpParams != NULL) 329 return p; 330 331 Error: 332 if (p -> Segments) _cmsFree(ContextID, p ->Segments); 333 if (p -> Evals) _cmsFree(ContextID, p -> Evals); 334 if (p ->Table16) _cmsFree(ContextID, p ->Table16); 335 _cmsFree(ContextID, p); 336 return NULL; 337 } 338 339 340 // Parametric Fn using floating point 341 static 342 cmsFloat64Number DefaultEvalParametricFn(cmsInt32Number Type, const cmsFloat64Number Params[], cmsFloat64Number R) 343 { 344 cmsFloat64Number e, Val, disc; 345 346 switch (Type) { 347 348 // X = Y ^ Gamma 349 case 1: 350 if (R < 0) { 351 352 if (fabs(Params[0] - 1.0) < MATRIX_DET_TOLERANCE) 353 Val = R; 354 else 355 Val = 0; 356 } 357 else 358 Val = pow(R, Params[0]); 359 break; 360 361 // Type 1 Reversed: X = Y ^1/gamma 362 case -1: 363 if (R < 0) { 364 365 if (fabs(Params[0] - 1.0) < MATRIX_DET_TOLERANCE) 366 Val = R; 367 else 368 Val = 0; 369 } 370 else 371 { 372 if (fabs(Params[0]) < MATRIX_DET_TOLERANCE) 373 Val = PLUS_INF; 374 else 375 Val = pow(R, 1 / Params[0]); 376 } 377 break; 378 379 // CIE 122-1966 380 // Y = (aX + b)^Gamma | X >= -b/a 381 // Y = 0 | else 382 case 2: 383 { 384 385 if (fabs(Params[1]) < MATRIX_DET_TOLERANCE) 386 { 387 Val = 0; 388 } 389 else 390 { 391 disc = -Params[2] / Params[1]; 392 393 if (R >= disc) { 394 395 e = Params[1] * R + Params[2]; 396 397 if (e > 0) 398 Val = pow(e, Params[0]); 399 else 400 Val = 0; 401 } 402 else 403 Val = 0; 404 } 405 } 406 break; 407 408 // Type 2 Reversed 409 // X = (Y ^1/g - b) / a 410 case -2: 411 { 412 if (fabs(Params[0]) < MATRIX_DET_TOLERANCE || 413 fabs(Params[1]) < MATRIX_DET_TOLERANCE) 414 { 415 Val = 0; 416 } 417 else 418 { 419 if (R < 0) 420 Val = 0; 421 else 422 Val = (pow(R, 1.0 / Params[0]) - Params[2]) / Params[1]; 423 424 if (Val < 0) 425 Val = 0; 426 } 427 } 428 break; 429 430 431 // IEC 61966-3 432 // Y = (aX + b)^Gamma | X <= -b/a 433 // Y = c | else 434 case 3: 435 { 436 if (fabs(Params[1]) < MATRIX_DET_TOLERANCE) 437 { 438 Val = 0; 439 } 440 else 441 { 442 disc = -Params[2] / Params[1]; 443 if (disc < 0) 444 disc = 0; 445 446 if (R >= disc) { 447 448 e = Params[1] * R + Params[2]; 449 450 if (e > 0) 451 Val = pow(e, Params[0]) + Params[3]; 452 else 453 Val = 0; 454 } 455 else 456 Val = Params[3]; 457 } 458 } 459 break; 460 461 462 // Type 3 reversed 463 // X=((Y-c)^1/g - b)/a | (Y>=c) 464 // X=-b/a | (Y<c) 465 case -3: 466 { 467 if (fabs(Params[1]) < MATRIX_DET_TOLERANCE) 468 { 469 Val = 0; 470 } 471 else 472 { 473 if (R >= Params[3]) { 474 475 e = R - Params[3]; 476 477 if (e > 0) 478 Val = (pow(e, 1 / Params[0]) - Params[2]) / Params[1]; 479 else 480 Val = 0; 481 } 482 else { 483 Val = -Params[2] / Params[1]; 484 } 485 } 486 } 487 break; 488 489 490 // IEC 61966-2.1 (sRGB) 491 // Y = (aX + b)^Gamma | X >= d 492 // Y = cX | X < d 493 case 4: 494 if (R >= Params[4]) { 495 496 e = Params[1]*R + Params[2]; 497 498 if (e > 0) 499 Val = pow(e, Params[0]); 500 else 501 Val = 0; 502 } 503 else 504 Val = R * Params[3]; 505 break; 506 507 // Type 4 reversed 508 // X=((Y^1/g-b)/a) | Y >= (ad+b)^g 509 // X=Y/c | Y< (ad+b)^g 510 case -4: 511 { 512 if (fabs(Params[0]) < MATRIX_DET_TOLERANCE || 513 fabs(Params[1]) < MATRIX_DET_TOLERANCE || 514 fabs(Params[3]) < MATRIX_DET_TOLERANCE) 515 { 516 Val = 0; 517 } 518 else 519 { 520 e = Params[1] * Params[4] + Params[2]; 521 if (e < 0) 522 disc = 0; 523 else 524 disc = pow(e, Params[0]); 525 526 if (R >= disc) { 527 528 Val = (pow(R, 1.0 / Params[0]) - Params[2]) / Params[1]; 529 } 530 else { 531 Val = R / Params[3]; 532 } 533 } 534 } 535 break; 536 537 538 // Y = (aX + b)^Gamma + e | X >= d 539 // Y = cX + f | X < d 540 case 5: 541 if (R >= Params[4]) { 542 543 e = Params[1]*R + Params[2]; 544 545 if (e > 0) 546 Val = pow(e, Params[0]) + Params[5]; 547 else 548 Val = Params[5]; 549 } 550 else 551 Val = R*Params[3] + Params[6]; 552 break; 553 554 555 // Reversed type 5 556 // X=((Y-e)1/g-b)/a | Y >=(ad+b)^g+e), cd+f 557 // X=(Y-f)/c | else 558 case -5: 559 { 560 if (fabs(Params[1]) < MATRIX_DET_TOLERANCE || 561 fabs(Params[3]) < MATRIX_DET_TOLERANCE) 562 { 563 Val = 0; 564 } 565 else 566 { 567 disc = Params[3] * Params[4] + Params[6]; 568 if (R >= disc) { 569 570 e = R - Params[5]; 571 if (e < 0) 572 Val = 0; 573 else 574 Val = (pow(e, 1.0 / Params[0]) - Params[2]) / Params[1]; 575 } 576 else { 577 Val = (R - Params[6]) / Params[3]; 578 } 579 } 580 } 581 break; 582 583 584 // Types 6,7,8 comes from segmented curves as described in ICCSpecRevision_02_11_06_Float.pdf 585 // Type 6 is basically identical to type 5 without d 586 587 // Y = (a * X + b) ^ Gamma + c 588 case 6: 589 e = Params[1]*R + Params[2]; 590 591 if (e < 0) 592 Val = Params[3]; 593 else 594 Val = pow(e, Params[0]) + Params[3]; 595 break; 596 597 // ((Y - c) ^1/Gamma - b) / a 598 case -6: 599 { 600 if (fabs(Params[1]) < MATRIX_DET_TOLERANCE) 601 { 602 Val = 0; 603 } 604 else 605 { 606 e = R - Params[3]; 607 if (e < 0) 608 Val = 0; 609 else 610 Val = (pow(e, 1.0 / Params[0]) - Params[2]) / Params[1]; 611 } 612 } 613 break; 614 615 616 // Y = a * log (b * X^Gamma + c) + d 617 case 7: 618 619 e = Params[2] * pow(R, Params[0]) + Params[3]; 620 if (e <= 0) 621 Val = Params[4]; 622 else 623 Val = Params[1]*log10(e) + Params[4]; 624 break; 625 626 // (Y - d) / a = log(b * X ^Gamma + c) 627 // pow(10, (Y-d) / a) = b * X ^Gamma + c 628 // pow((pow(10, (Y-d) / a) - c) / b, 1/g) = X 629 case -7: 630 { 631 if (fabs(Params[0]) < MATRIX_DET_TOLERANCE || 632 fabs(Params[1]) < MATRIX_DET_TOLERANCE || 633 fabs(Params[2]) < MATRIX_DET_TOLERANCE) 634 { 635 Val = 0; 636 } 637 else 638 { 639 Val = pow((pow(10.0, (R - Params[4]) / Params[1]) - Params[3]) / Params[2], 1.0 / Params[0]); 640 } 641 } 642 break; 643 644 645 //Y = a * b^(c*X+d) + e 646 case 8: 647 Val = (Params[0] * pow(Params[1], Params[2] * R + Params[3]) + Params[4]); 648 break; 649 650 651 // Y = (log((y-e) / a) / log(b) - d ) / c 652 // a=0, b=1, c=2, d=3, e=4, 653 case -8: 654 655 disc = R - Params[4]; 656 if (disc < 0) Val = 0; 657 else 658 { 659 if (fabs(Params[0]) < MATRIX_DET_TOLERANCE || 660 fabs(Params[2]) < MATRIX_DET_TOLERANCE) 661 { 662 Val = 0; 663 } 664 else 665 { 666 Val = (log(disc / Params[0]) / log(Params[1]) - Params[3]) / Params[2]; 667 } 668 } 669 break; 670 671 // S-Shaped: (1 - (1-x)^1/g)^1/g 672 case 108: 673 if (fabs(Params[0]) < MATRIX_DET_TOLERANCE) 674 Val = 0; 675 else 676 Val = pow(1.0 - pow(1 - R, 1/Params[0]), 1/Params[0]); 677 break; 678 679 // y = (1 - (1-x)^1/g)^1/g 680 // y^g = (1 - (1-x)^1/g) 681 // 1 - y^g = (1-x)^1/g 682 // (1 - y^g)^g = 1 - x 683 // 1 - (1 - y^g)^g 684 case -108: 685 Val = 1 - pow(1 - pow(R, Params[0]), Params[0]); 686 break; 687 688 default: 689 // Unsupported parametric curve. Should never reach here 690 return 0; 691 } 692 693 return Val; 694 } 695 696 // Evaluate a segmented function for a single value. Return -Inf if no valid segment found . 697 // If fn type is 0, perform an interpolation on the table 698 static 699 cmsFloat64Number EvalSegmentedFn(const cmsToneCurve *g, cmsFloat64Number R) 700 { 701 int i; 702 cmsFloat32Number Out32; 703 cmsFloat64Number Out; 704 705 for (i = (int) g->nSegments - 1; i >= 0; --i) { 706 707 // Check for domain 708 if ((R > g->Segments[i].x0) && (R <= g->Segments[i].x1)) { 709 710 // Type == 0 means segment is sampled 711 if (g->Segments[i].Type == 0) { 712 713 cmsFloat32Number R1 = (cmsFloat32Number)(R - g->Segments[i].x0) / (g->Segments[i].x1 - g->Segments[i].x0); 714 715 // Setup the table (TODO: clean that) 716 g->SegInterp[i]->Table = g->Segments[i].SampledPoints; 717 718 g->SegInterp[i]->Interpolation.LerpFloat(&R1, &Out32, g->SegInterp[i]); 719 Out = (cmsFloat64Number) Out32; 720 721 } 722 else { 723 Out = g->Evals[i](g->Segments[i].Type, g->Segments[i].Params, R); 724 } 725 726 if (isinf(Out)) 727 return PLUS_INF; 728 else 729 { 730 if (isinf(-Out)) 731 return MINUS_INF; 732 } 733 734 return Out; 735 } 736 } 737 738 return MINUS_INF; 739 } 740 741 // Access to estimated low-res table 742 cmsUInt32Number CMSEXPORT cmsGetToneCurveEstimatedTableEntries(const cmsToneCurve* t) 743 { 744 _cmsAssert(t != NULL); 745 return t ->nEntries; 746 } 747 748 const cmsUInt16Number* CMSEXPORT cmsGetToneCurveEstimatedTable(const cmsToneCurve* t) 749 { 750 _cmsAssert(t != NULL); 751 return t ->Table16; 752 } 753 754 755 // Create an empty gamma curve, by using tables. This specifies only the limited-precision part, and leaves the 756 // floating point description empty. 757 cmsToneCurve* CMSEXPORT cmsBuildTabulatedToneCurve16(cmsContext ContextID, cmsUInt32Number nEntries, const cmsUInt16Number Values[]) 758 { 759 return AllocateToneCurveStruct(ContextID, nEntries, 0, NULL, Values); 760 } 761 762 static 763 cmsUInt32Number EntriesByGamma(cmsFloat64Number Gamma) 764 { 765 if (fabs(Gamma - 1.0) < 0.001) return 2; 766 return 4096; 767 } 768 769 770 // Create a segmented gamma, fill the table 771 cmsToneCurve* CMSEXPORT cmsBuildSegmentedToneCurve(cmsContext ContextID, 772 cmsUInt32Number nSegments, const cmsCurveSegment Segments[]) 773 { 774 cmsUInt32Number i; 775 cmsFloat64Number R, Val; 776 cmsToneCurve* g; 777 cmsUInt32Number nGridPoints = 4096; 778 779 _cmsAssert(Segments != NULL); 780 781 // Optimizatin for identity curves. 782 if (nSegments == 1 && Segments[0].Type == 1) { 783 784 nGridPoints = EntriesByGamma(Segments[0].Params[0]); 785 } 786 787 g = AllocateToneCurveStruct(ContextID, nGridPoints, nSegments, Segments, NULL); 788 if (g == NULL) return NULL; 789 790 // Once we have the floating point version, we can approximate a 16 bit table of 4096 entries 791 // for performance reasons. This table would normally not be used except on 8/16 bits transforms. 792 for (i = 0; i < nGridPoints; i++) { 793 794 R = (cmsFloat64Number) i / (nGridPoints-1); 795 796 Val = EvalSegmentedFn(g, R); 797 798 // Round and saturate 799 g ->Table16[i] = _cmsQuickSaturateWord(Val * 65535.0); 800 } 801 802 return g; 803 } 804 805 // Use a segmented curve to store the floating point table 806 cmsToneCurve* CMSEXPORT cmsBuildTabulatedToneCurveFloat(cmsContext ContextID, cmsUInt32Number nEntries, const cmsFloat32Number values[]) 807 { 808 cmsCurveSegment Seg[3]; 809 810 // A segmented tone curve should have function segments in the first and last positions 811 // Initialize segmented curve part up to 0 to constant value = samples[0] 812 Seg[0].x0 = MINUS_INF; 813 Seg[0].x1 = 0; 814 Seg[0].Type = 6; 815 816 Seg[0].Params[0] = 1; 817 Seg[0].Params[1] = 0; 818 Seg[0].Params[2] = 0; 819 Seg[0].Params[3] = values[0]; 820 Seg[0].Params[4] = 0; 821 822 // From zero to 1 823 Seg[1].x0 = 0; 824 Seg[1].x1 = 1.0; 825 Seg[1].Type = 0; 826 827 Seg[1].nGridPoints = nEntries; 828 Seg[1].SampledPoints = (cmsFloat32Number*) values; 829 830 // Final segment is constant = lastsample 831 Seg[2].x0 = 1.0; 832 Seg[2].x1 = PLUS_INF; 833 Seg[2].Type = 6; 834 835 Seg[2].Params[0] = 1; 836 Seg[2].Params[1] = 0; 837 Seg[2].Params[2] = 0; 838 Seg[2].Params[3] = values[nEntries-1]; 839 Seg[2].Params[4] = 0; 840 841 842 return cmsBuildSegmentedToneCurve(ContextID, 3, Seg); 843 } 844 845 // Parametric curves 846 // 847 // Parameters goes as: Curve, a, b, c, d, e, f 848 // Type is the ICC type +1 849 // if type is negative, then the curve is analyticaly inverted 850 cmsToneCurve* CMSEXPORT cmsBuildParametricToneCurve(cmsContext ContextID, cmsInt32Number Type, const cmsFloat64Number Params[]) 851 { 852 cmsCurveSegment Seg0; 853 int Pos = 0; 854 cmsUInt32Number size; 855 _cmsParametricCurvesCollection* c = GetParametricCurveByType(ContextID, Type, &Pos); 856 857 _cmsAssert(Params != NULL); 858 859 if (c == NULL) { 860 cmsSignalError(ContextID, cmsERROR_UNKNOWN_EXTENSION, "Invalid parametric curve type %d", Type); 861 return NULL; 862 } 863 864 memset(&Seg0, 0, sizeof(Seg0)); 865 866 Seg0.x0 = MINUS_INF; 867 Seg0.x1 = PLUS_INF; 868 Seg0.Type = Type; 869 870 size = c->ParameterCount[Pos] * sizeof(cmsFloat64Number); 871 memmove(Seg0.Params, Params, size); 872 873 return cmsBuildSegmentedToneCurve(ContextID, 1, &Seg0); 874 } 875 876 877 878 // Build a gamma table based on gamma constant 879 cmsToneCurve* CMSEXPORT cmsBuildGamma(cmsContext ContextID, cmsFloat64Number Gamma) 880 { 881 return cmsBuildParametricToneCurve(ContextID, 1, &Gamma); 882 } 883 884 885 // Free all memory taken by the gamma curve 886 void CMSEXPORT cmsFreeToneCurve(cmsToneCurve* Curve) 887 { 888 cmsContext ContextID; 889 890 if (Curve == NULL) return; 891 892 ContextID = Curve ->InterpParams->ContextID; 893 894 _cmsFreeInterpParams(Curve ->InterpParams); 895 896 if (Curve -> Table16) 897 _cmsFree(ContextID, Curve ->Table16); 898 899 if (Curve ->Segments) { 900 901 cmsUInt32Number i; 902 903 for (i=0; i < Curve ->nSegments; i++) { 904 905 if (Curve ->Segments[i].SampledPoints) { 906 _cmsFree(ContextID, Curve ->Segments[i].SampledPoints); 907 } 908 909 if (Curve ->SegInterp[i] != 0) 910 _cmsFreeInterpParams(Curve->SegInterp[i]); 911 } 912 913 _cmsFree(ContextID, Curve ->Segments); 914 _cmsFree(ContextID, Curve ->SegInterp); 915 } 916 917 if (Curve -> Evals) 918 _cmsFree(ContextID, Curve -> Evals); 919 920 if (Curve) _cmsFree(ContextID, Curve); 921 } 922 923 // Utility function, free 3 gamma tables 924 void CMSEXPORT cmsFreeToneCurveTriple(cmsToneCurve* Curve[3]) 925 { 926 927 _cmsAssert(Curve != NULL); 928 929 if (Curve[0] != NULL) cmsFreeToneCurve(Curve[0]); 930 if (Curve[1] != NULL) cmsFreeToneCurve(Curve[1]); 931 if (Curve[2] != NULL) cmsFreeToneCurve(Curve[2]); 932 933 Curve[0] = Curve[1] = Curve[2] = NULL; 934 } 935 936 937 // Duplicate a gamma table 938 cmsToneCurve* CMSEXPORT cmsDupToneCurve(const cmsToneCurve* In) 939 { 940 if (In == NULL) return NULL; 941 942 return AllocateToneCurveStruct(In ->InterpParams ->ContextID, In ->nEntries, In ->nSegments, In ->Segments, In ->Table16); 943 } 944 945 // Joins two curves for X and Y. Curves should be monotonic. 946 // We want to get 947 // 948 // y = Y^-1(X(t)) 949 // 950 cmsToneCurve* CMSEXPORT cmsJoinToneCurve(cmsContext ContextID, 951 const cmsToneCurve* X, 952 const cmsToneCurve* Y, cmsUInt32Number nResultingPoints) 953 { 954 cmsToneCurve* out = NULL; 955 cmsToneCurve* Yreversed = NULL; 956 cmsFloat32Number t, x; 957 cmsFloat32Number* Res = NULL; 958 cmsUInt32Number i; 959 960 961 _cmsAssert(X != NULL); 962 _cmsAssert(Y != NULL); 963 964 Yreversed = cmsReverseToneCurveEx(nResultingPoints, Y); 965 if (Yreversed == NULL) goto Error; 966 967 Res = (cmsFloat32Number*) _cmsCalloc(ContextID, nResultingPoints, sizeof(cmsFloat32Number)); 968 if (Res == NULL) goto Error; 969 970 //Iterate 971 for (i=0; i < nResultingPoints; i++) { 972 973 t = (cmsFloat32Number) i / (nResultingPoints-1); 974 x = cmsEvalToneCurveFloat(X, t); 975 Res[i] = cmsEvalToneCurveFloat(Yreversed, x); 976 } 977 978 // Allocate space for output 979 out = cmsBuildTabulatedToneCurveFloat(ContextID, nResultingPoints, Res); 980 981 Error: 982 983 if (Res != NULL) _cmsFree(ContextID, Res); 984 if (Yreversed != NULL) cmsFreeToneCurve(Yreversed); 985 986 return out; 987 } 988 989 990 991 // Get the surrounding nodes. This is tricky on non-monotonic tables 992 static 993 int GetInterval(cmsFloat64Number In, const cmsUInt16Number LutTable[], const struct _cms_interp_struc* p) 994 { 995 int i; 996 int y0, y1; 997 998 // A 1 point table is not allowed 999 if (p -> Domain[0] < 1) return -1; 1000 1001 // Let's see if ascending or descending. 1002 if (LutTable[0] < LutTable[p ->Domain[0]]) { 1003 1004 // Table is overall ascending 1005 for (i = (int) p->Domain[0] - 1; i >= 0; --i) { 1006 1007 y0 = LutTable[i]; 1008 y1 = LutTable[i+1]; 1009 1010 if (y0 <= y1) { // Increasing 1011 if (In >= y0 && In <= y1) return i; 1012 } 1013 else 1014 if (y1 < y0) { // Decreasing 1015 if (In >= y1 && In <= y0) return i; 1016 } 1017 } 1018 } 1019 else { 1020 // Table is overall descending 1021 for (i=0; i < (int) p -> Domain[0]; i++) { 1022 1023 y0 = LutTable[i]; 1024 y1 = LutTable[i+1]; 1025 1026 if (y0 <= y1) { // Increasing 1027 if (In >= y0 && In <= y1) return i; 1028 } 1029 else 1030 if (y1 < y0) { // Decreasing 1031 if (In >= y1 && In <= y0) return i; 1032 } 1033 } 1034 } 1035 1036 return -1; 1037 } 1038 1039 // Reverse a gamma table 1040 cmsToneCurve* CMSEXPORT cmsReverseToneCurveEx(cmsUInt32Number nResultSamples, const cmsToneCurve* InCurve) 1041 { 1042 cmsToneCurve *out; 1043 cmsFloat64Number a = 0, b = 0, y, x1, y1, x2, y2; 1044 int i, j; 1045 int Ascending; 1046 1047 _cmsAssert(InCurve != NULL); 1048 1049 // Try to reverse it analytically whatever possible 1050 1051 if (InCurve ->nSegments == 1 && InCurve ->Segments[0].Type > 0 && 1052 /* InCurve -> Segments[0].Type <= 5 */ 1053 GetParametricCurveByType(InCurve ->InterpParams->ContextID, InCurve ->Segments[0].Type, NULL) != NULL) { 1054 1055 return cmsBuildParametricToneCurve(InCurve ->InterpParams->ContextID, 1056 -(InCurve -> Segments[0].Type), 1057 InCurve -> Segments[0].Params); 1058 } 1059 1060 // Nope, reverse the table. 1061 out = cmsBuildTabulatedToneCurve16(InCurve ->InterpParams->ContextID, nResultSamples, NULL); 1062 if (out == NULL) 1063 return NULL; 1064 1065 // We want to know if this is an ascending or descending table 1066 Ascending = !cmsIsToneCurveDescending(InCurve); 1067 1068 // Iterate across Y axis 1069 for (i=0; i < (int) nResultSamples; i++) { 1070 1071 y = (cmsFloat64Number) i * 65535.0 / (nResultSamples - 1); 1072 1073 // Find interval in which y is within. 1074 j = GetInterval(y, InCurve->Table16, InCurve->InterpParams); 1075 if (j >= 0) { 1076 1077 1078 // Get limits of interval 1079 x1 = InCurve ->Table16[j]; 1080 x2 = InCurve ->Table16[j+1]; 1081 1082 y1 = (cmsFloat64Number) (j * 65535.0) / (InCurve ->nEntries - 1); 1083 y2 = (cmsFloat64Number) ((j+1) * 65535.0 ) / (InCurve ->nEntries - 1); 1084 1085 // If collapsed, then use any 1086 if (x1 == x2) { 1087 1088 out ->Table16[i] = _cmsQuickSaturateWord(Ascending ? y2 : y1); 1089 continue; 1090 1091 } else { 1092 1093 // Interpolate 1094 a = (y2 - y1) / (x2 - x1); 1095 b = y2 - a * x2; 1096 } 1097 } 1098 1099 out ->Table16[i] = _cmsQuickSaturateWord(a* y + b); 1100 } 1101 1102 1103 return out; 1104 } 1105 1106 // Reverse a gamma table 1107 cmsToneCurve* CMSEXPORT cmsReverseToneCurve(const cmsToneCurve* InGamma) 1108 { 1109 _cmsAssert(InGamma != NULL); 1110 1111 return cmsReverseToneCurveEx(4096, InGamma); 1112 } 1113 1114 // From: Eilers, P.H.C. (1994) Smoothing and interpolation with finite 1115 // differences. in: Graphic Gems IV, Heckbert, P.S. (ed.), Academic press. 1116 // 1117 // Smoothing and interpolation with second differences. 1118 // 1119 // Input: weights (w), data (y): vector from 1 to m. 1120 // Input: smoothing parameter (lambda), length (m). 1121 // Output: smoothed vector (z): vector from 1 to m. 1122 1123 static 1124 cmsBool smooth2(cmsContext ContextID, cmsFloat32Number w[], cmsFloat32Number y[], 1125 cmsFloat32Number z[], cmsFloat32Number lambda, int m) 1126 { 1127 int i, i1, i2; 1128 cmsFloat32Number *c, *d, *e; 1129 cmsBool st; 1130 1131 1132 c = (cmsFloat32Number*) _cmsCalloc(ContextID, MAX_NODES_IN_CURVE, sizeof(cmsFloat32Number)); 1133 d = (cmsFloat32Number*) _cmsCalloc(ContextID, MAX_NODES_IN_CURVE, sizeof(cmsFloat32Number)); 1134 e = (cmsFloat32Number*) _cmsCalloc(ContextID, MAX_NODES_IN_CURVE, sizeof(cmsFloat32Number)); 1135 1136 if (c != NULL && d != NULL && e != NULL) { 1137 1138 1139 d[1] = w[1] + lambda; 1140 c[1] = -2 * lambda / d[1]; 1141 e[1] = lambda /d[1]; 1142 z[1] = w[1] * y[1]; 1143 d[2] = w[2] + 5 * lambda - d[1] * c[1] * c[1]; 1144 c[2] = (-4 * lambda - d[1] * c[1] * e[1]) / d[2]; 1145 e[2] = lambda / d[2]; 1146 z[2] = w[2] * y[2] - c[1] * z[1]; 1147 1148 for (i = 3; i < m - 1; i++) { 1149 i1 = i - 1; i2 = i - 2; 1150 d[i]= w[i] + 6 * lambda - c[i1] * c[i1] * d[i1] - e[i2] * e[i2] * d[i2]; 1151 c[i] = (-4 * lambda -d[i1] * c[i1] * e[i1])/ d[i]; 1152 e[i] = lambda / d[i]; 1153 z[i] = w[i] * y[i] - c[i1] * z[i1] - e[i2] * z[i2]; 1154 } 1155 1156 i1 = m - 2; i2 = m - 3; 1157 1158 d[m - 1] = w[m - 1] + 5 * lambda -c[i1] * c[i1] * d[i1] - e[i2] * e[i2] * d[i2]; 1159 c[m - 1] = (-2 * lambda - d[i1] * c[i1] * e[i1]) / d[m - 1]; 1160 z[m - 1] = w[m - 1] * y[m - 1] - c[i1] * z[i1] - e[i2] * z[i2]; 1161 i1 = m - 1; i2 = m - 2; 1162 1163 d[m] = w[m] + lambda - c[i1] * c[i1] * d[i1] - e[i2] * e[i2] * d[i2]; 1164 z[m] = (w[m] * y[m] - c[i1] * z[i1] - e[i2] * z[i2]) / d[m]; 1165 z[m - 1] = z[m - 1] / d[m - 1] - c[m - 1] * z[m]; 1166 1167 for (i = m - 2; 1<= i; i--) 1168 z[i] = z[i] / d[i] - c[i] * z[i + 1] - e[i] * z[i + 2]; 1169 1170 st = TRUE; 1171 } 1172 else st = FALSE; 1173 1174 if (c != NULL) _cmsFree(ContextID, c); 1175 if (d != NULL) _cmsFree(ContextID, d); 1176 if (e != NULL) _cmsFree(ContextID, e); 1177 1178 return st; 1179 } 1180 1181 // Smooths a curve sampled at regular intervals. 1182 cmsBool CMSEXPORT cmsSmoothToneCurve(cmsToneCurve* Tab, cmsFloat64Number lambda) 1183 { 1184 cmsBool SuccessStatus = TRUE; 1185 cmsFloat32Number *w, *y, *z; 1186 cmsUInt32Number i, nItems, Zeros, Poles; 1187 1188 if (Tab != NULL && Tab->InterpParams != NULL) 1189 { 1190 cmsContext ContextID = Tab->InterpParams->ContextID; 1191 1192 if (!cmsIsToneCurveLinear(Tab)) // Only non-linear curves need smoothing 1193 { 1194 nItems = Tab->nEntries; 1195 if (nItems < MAX_NODES_IN_CURVE) 1196 { 1197 // Allocate one more item than needed 1198 w = (cmsFloat32Number *)_cmsCalloc(ContextID, nItems + 1, sizeof(cmsFloat32Number)); 1199 y = (cmsFloat32Number *)_cmsCalloc(ContextID, nItems + 1, sizeof(cmsFloat32Number)); 1200 z = (cmsFloat32Number *)_cmsCalloc(ContextID, nItems + 1, sizeof(cmsFloat32Number)); 1201 1202 if (w != NULL && y != NULL && z != NULL) // Ensure no memory allocation failure 1203 { 1204 memset(w, 0, (nItems + 1) * sizeof(cmsFloat32Number)); 1205 memset(y, 0, (nItems + 1) * sizeof(cmsFloat32Number)); 1206 memset(z, 0, (nItems + 1) * sizeof(cmsFloat32Number)); 1207 1208 for (i = 0; i < nItems; i++) 1209 { 1210 y[i + 1] = (cmsFloat32Number)Tab->Table16[i]; 1211 w[i + 1] = 1.0; 1212 } 1213 1214 if (smooth2(ContextID, w, y, z, (cmsFloat32Number)lambda, (int)nItems)) 1215 { 1216 // Do some reality - checking... 1217 1218 Zeros = Poles = 0; 1219 for (i = nItems; i > 1; --i) 1220 { 1221 if (z[i] == 0.) Zeros++; 1222 if (z[i] >= 65535.) Poles++; 1223 if (z[i] < z[i - 1]) 1224 { 1225 cmsSignalError(ContextID, cmsERROR_RANGE, "cmsSmoothToneCurve: Non-Monotonic."); 1226 SuccessStatus = FALSE; 1227 break; 1228 } 1229 } 1230 1231 if (SuccessStatus && Zeros > (nItems / 3)) 1232 { 1233 cmsSignalError(ContextID, cmsERROR_RANGE, "cmsSmoothToneCurve: Degenerated, mostly zeros."); 1234 SuccessStatus = FALSE; 1235 } 1236 1237 if (SuccessStatus && Poles > (nItems / 3)) 1238 { 1239 cmsSignalError(ContextID, cmsERROR_RANGE, "cmsSmoothToneCurve: Degenerated, mostly poles."); 1240 SuccessStatus = FALSE; 1241 } 1242 1243 if (SuccessStatus) // Seems ok 1244 { 1245 for (i = 0; i < nItems; i++) 1246 { 1247 // Clamp to cmsUInt16Number 1248 Tab->Table16[i] = _cmsQuickSaturateWord(z[i + 1]); 1249 } 1250 } 1251 } 1252 else // Could not smooth 1253 { 1254 cmsSignalError(ContextID, cmsERROR_RANGE, "cmsSmoothToneCurve: Function smooth2 failed."); 1255 SuccessStatus = FALSE; 1256 } 1257 } 1258 else // One or more buffers could not be allocated 1259 { 1260 cmsSignalError(ContextID, cmsERROR_RANGE, "cmsSmoothToneCurve: Could not allocate memory."); 1261 SuccessStatus = FALSE; 1262 } 1263 1264 if (z != NULL) 1265 _cmsFree(ContextID, z); 1266 1267 if (y != NULL) 1268 _cmsFree(ContextID, y); 1269 1270 if (w != NULL) 1271 _cmsFree(ContextID, w); 1272 } 1273 else // too many items in the table 1274 { 1275 cmsSignalError(ContextID, cmsERROR_RANGE, "cmsSmoothToneCurve: Too many points."); 1276 SuccessStatus = FALSE; 1277 } 1278 } 1279 } 1280 else // Tab parameter or Tab->InterpParams is NULL 1281 { 1282 // Can't signal an error here since the ContextID is not known at this point 1283 SuccessStatus = FALSE; 1284 } 1285 1286 return SuccessStatus; 1287 } 1288 1289 // Is a table linear? Do not use parametric since we cannot guarantee some weird parameters resulting 1290 // in a linear table. This way assures it is linear in 12 bits, which should be enought in most cases. 1291 cmsBool CMSEXPORT cmsIsToneCurveLinear(const cmsToneCurve* Curve) 1292 { 1293 int i; 1294 int diff; 1295 1296 _cmsAssert(Curve != NULL); 1297 1298 for (i=0; i < (int) Curve ->nEntries; i++) { 1299 1300 diff = abs((int) Curve->Table16[i] - (int) _cmsQuantizeVal(i, Curve ->nEntries)); 1301 if (diff > 0x0f) 1302 return FALSE; 1303 } 1304 1305 return TRUE; 1306 } 1307 1308 // Same, but for monotonicity 1309 cmsBool CMSEXPORT cmsIsToneCurveMonotonic(const cmsToneCurve* t) 1310 { 1311 cmsUInt32Number n; 1312 int i, last; 1313 cmsBool lDescending; 1314 1315 _cmsAssert(t != NULL); 1316 1317 // Degenerated curves are monotonic? Ok, let's pass them 1318 n = t ->nEntries; 1319 if (n < 2) return TRUE; 1320 1321 // Curve direction 1322 lDescending = cmsIsToneCurveDescending(t); 1323 1324 if (lDescending) { 1325 1326 last = t ->Table16[0]; 1327 1328 for (i = 1; i < (int) n; i++) { 1329 1330 if (t ->Table16[i] - last > 2) // We allow some ripple 1331 return FALSE; 1332 else 1333 last = t ->Table16[i]; 1334 1335 } 1336 } 1337 else { 1338 1339 last = t ->Table16[n-1]; 1340 1341 for (i = (int) n - 2; i >= 0; --i) { 1342 1343 if (t ->Table16[i] - last > 2) 1344 return FALSE; 1345 else 1346 last = t ->Table16[i]; 1347 1348 } 1349 } 1350 1351 return TRUE; 1352 } 1353 1354 // Same, but for descending tables 1355 cmsBool CMSEXPORT cmsIsToneCurveDescending(const cmsToneCurve* t) 1356 { 1357 _cmsAssert(t != NULL); 1358 1359 return t ->Table16[0] > t ->Table16[t ->nEntries-1]; 1360 } 1361 1362 1363 // Another info fn: is out gamma table multisegment? 1364 cmsBool CMSEXPORT cmsIsToneCurveMultisegment(const cmsToneCurve* t) 1365 { 1366 _cmsAssert(t != NULL); 1367 1368 return t -> nSegments > 1; 1369 } 1370 1371 cmsInt32Number CMSEXPORT cmsGetToneCurveParametricType(const cmsToneCurve* t) 1372 { 1373 _cmsAssert(t != NULL); 1374 1375 if (t -> nSegments != 1) return 0; 1376 return t ->Segments[0].Type; 1377 } 1378 1379 // We need accuracy this time 1380 cmsFloat32Number CMSEXPORT cmsEvalToneCurveFloat(const cmsToneCurve* Curve, cmsFloat32Number v) 1381 { 1382 _cmsAssert(Curve != NULL); 1383 1384 // Check for 16 bits table. If so, this is a limited-precision tone curve 1385 if (Curve ->nSegments == 0) { 1386 1387 cmsUInt16Number In, Out; 1388 1389 In = (cmsUInt16Number) _cmsQuickSaturateWord(v * 65535.0); 1390 Out = cmsEvalToneCurve16(Curve, In); 1391 1392 return (cmsFloat32Number) (Out / 65535.0); 1393 } 1394 1395 return (cmsFloat32Number) EvalSegmentedFn(Curve, v); 1396 } 1397 1398 // We need xput over here 1399 cmsUInt16Number CMSEXPORT cmsEvalToneCurve16(const cmsToneCurve* Curve, cmsUInt16Number v) 1400 { 1401 cmsUInt16Number out; 1402 1403 _cmsAssert(Curve != NULL); 1404 1405 Curve ->InterpParams ->Interpolation.Lerp16(&v, &out, Curve ->InterpParams); 1406 return out; 1407 } 1408 1409 1410 // Least squares fitting. 1411 // A mathematical procedure for finding the best-fitting curve to a given set of points by 1412 // minimizing the sum of the squares of the offsets ("the residuals") of the points from the curve. 1413 // The sum of the squares of the offsets is used instead of the offset absolute values because 1414 // this allows the residuals to be treated as a continuous differentiable quantity. 1415 // 1416 // y = f(x) = x ^ g 1417 // 1418 // R = (yi - (xi^g)) 1419 // R2 = (yi - (xi^g))2 1420 // SUM R2 = SUM (yi - (xi^g))2 1421 // 1422 // dR2/dg = -2 SUM x^g log(x)(y - x^g) 1423 // solving for dR2/dg = 0 1424 // 1425 // g = 1/n * SUM(log(y) / log(x)) 1426 1427 cmsFloat64Number CMSEXPORT cmsEstimateGamma(const cmsToneCurve* t, cmsFloat64Number Precision) 1428 { 1429 cmsFloat64Number gamma, sum, sum2; 1430 cmsFloat64Number n, x, y, Std; 1431 cmsUInt32Number i; 1432 1433 _cmsAssert(t != NULL); 1434 1435 sum = sum2 = n = 0; 1436 1437 // Excluding endpoints 1438 for (i=1; i < (MAX_NODES_IN_CURVE-1); i++) { 1439 1440 x = (cmsFloat64Number) i / (MAX_NODES_IN_CURVE-1); 1441 y = (cmsFloat64Number) cmsEvalToneCurveFloat(t, (cmsFloat32Number) x); 1442 1443 // Avoid 7% on lower part to prevent 1444 // artifacts due to linear ramps 1445 1446 if (y > 0. && y < 1. && x > 0.07) { 1447 1448 gamma = log(y) / log(x); 1449 sum += gamma; 1450 sum2 += gamma * gamma; 1451 n++; 1452 } 1453 } 1454 1455 // Take a look on SD to see if gamma isn't exponential at all 1456 Std = sqrt((n * sum2 - sum * sum) / (n*(n-1))); 1457 1458 if (Std > Precision) 1459 return -1.0; 1460 1461 return (sum / n); // The mean 1462 }