1/* 2%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 3% % 4% % 5% % 6% RRRR EEEEE SSSSS AAA M M PPPP L EEEEE % 7% R R E SS A A MM MM P P L E % 8% RRRR EEE SSS AAAAA M M M PPPP L EEE % 9% R R E SS A A M M P L E % 10% R R EEEEE SSSSS A A M M P LLLLL EEEEE % 11% % 12% % 13% MagickCore Pixel Resampling Methods % 14% % 15% Software Design % 16% Cristy % 17% Anthony Thyssen % 18% August 2007 % 19% % 20% % 21% Copyright 1999-2016 ImageMagick Studio LLC, a non-profit organization % 22% dedicated to making software imaging solutions freely available. % 23% % 24% You may not use this file except in compliance with the License. You may % 25% obtain a copy of the License at % 26% % 27% http://www.imagemagick.org/script/license.php % 28% % 29% Unless required by applicable law or agreed to in writing, software % 30% distributed under the License is distributed on an "AS IS" BASIS, % 31% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. % 32% See the License for the specific language governing permissions and % 33% limitations under the License. % 34% % 35%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 36% 37% 38*/ 39 40/* 41 Include declarations. 42*/ 43#include "MagickCore/studio.h" 44#include "MagickCore/artifact.h" 45#include "MagickCore/color-private.h" 46#include "MagickCore/cache.h" 47#include "MagickCore/draw.h" 48#include "MagickCore/exception-private.h" 49#include "MagickCore/gem.h" 50#include "MagickCore/image.h" 51#include "MagickCore/image-private.h" 52#include "MagickCore/log.h" 53#include "MagickCore/magick.h" 54#include "MagickCore/memory_.h" 55#include "MagickCore/pixel.h" 56#include "MagickCore/pixel-accessor.h" 57#include "MagickCore/quantum.h" 58#include "MagickCore/random_.h" 59#include "MagickCore/resample.h" 60#include "MagickCore/resize.h" 61#include "MagickCore/resize-private.h" 62#include "MagickCore/resource_.h" 63#include "MagickCore/token.h" 64#include "MagickCore/transform.h" 65#include "MagickCore/signature-private.h" 66#include "MagickCore/utility.h" 67#include "MagickCore/utility-private.h" 68#include "MagickCore/option.h" 69/* 70 EWA Resampling Options 71*/ 72 73/* select ONE resampling method */ 74#define EWA 1 /* Normal EWA handling - raw or clamped */ 75 /* if 0 then use "High Quality EWA" */ 76#define EWA_CLAMP 1 /* EWA Clamping from Nicolas Robidoux */ 77 78#define FILTER_LUT 1 /* Use a LUT rather then direct filter calls */ 79 80/* output debugging information */ 81#define DEBUG_ELLIPSE 0 /* output ellipse info for debug */ 82#define DEBUG_HIT_MISS 0 /* output hit/miss pixels (as gnuplot commands) */ 83#define DEBUG_NO_PIXEL_HIT 0 /* Make pixels that fail to hit anything - RED */ 84 85#if ! FILTER_DIRECT 86#define WLUT_WIDTH 1024 /* size of the filter cache */ 87#endif 88 89/* 90 Typedef declarations. 91*/ 92struct _ResampleFilter 93{ 94 CacheView 95 *view; 96 97 Image 98 *image; 99 100 ExceptionInfo 101 *exception; 102 103 MagickBooleanType 104 debug; 105 106 /* Information about image being resampled */ 107 ssize_t 108 image_area; 109 110 PixelInterpolateMethod 111 interpolate; 112 113 VirtualPixelMethod 114 virtual_pixel; 115 116 FilterType 117 filter; 118 119 /* processing settings needed */ 120 MagickBooleanType 121 limit_reached, 122 do_interpolate, 123 average_defined; 124 125 PixelInfo 126 average_pixel; 127 128 /* current ellipitical area being resampled around center point */ 129 double 130 A, B, C, 131 Vlimit, Ulimit, Uwidth, slope; 132 133#if FILTER_LUT 134 /* LUT of weights for filtered average in elliptical area */ 135 double 136 filter_lut[WLUT_WIDTH]; 137#else 138 /* Use a Direct call to the filter functions */ 139 ResizeFilter 140 *filter_def; 141 142 double 143 F; 144#endif 145 146 /* the practical working support of the filter */ 147 double 148 support; 149 150 size_t 151 signature; 152}; 153 154/* 155%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 156% % 157% % 158% % 159% A c q u i r e R e s a m p l e I n f o % 160% % 161% % 162% % 163%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 164% 165% AcquireResampleFilter() initializes the information resample needs do to a 166% scaled lookup of a color from an image, using area sampling. 167% 168% The algorithm is based on a Elliptical Weighted Average, where the pixels 169% found in a large elliptical area is averaged together according to a 170% weighting (filter) function. For more details see "Fundamentals of Texture 171% Mapping and Image Warping" a master's thesis by Paul.S.Heckbert, June 17, 172% 1989. Available for free from, http://www.cs.cmu.edu/~ph/ 173% 174% As EWA resampling (or any sort of resampling) can require a lot of 175% calculations to produce a distorted scaling of the source image for each 176% output pixel, the ResampleFilter structure generated holds that information 177% between individual image resampling. 178% 179% This function will make the appropriate AcquireCacheView() calls 180% to view the image, calling functions do not need to open a cache view. 181% 182% Usage Example... 183% resample_filter=AcquireResampleFilter(image,exception); 184% SetResampleFilter(resample_filter, GaussianFilter); 185% for (y=0; y < (ssize_t) image->rows; y++) { 186% for (x=0; x < (ssize_t) image->columns; x++) { 187% u= ....; v= ....; 188% ScaleResampleFilter(resample_filter, ... scaling vectors ...); 189% (void) ResamplePixelColor(resample_filter,u,v,&pixel); 190% ... assign resampled pixel value ... 191% } 192% } 193% DestroyResampleFilter(resample_filter); 194% 195% The format of the AcquireResampleFilter method is: 196% 197% ResampleFilter *AcquireResampleFilter(const Image *image, 198% ExceptionInfo *exception) 199% 200% A description of each parameter follows: 201% 202% o image: the image. 203% 204% o exception: return any errors or warnings in this structure. 205% 206*/ 207MagickExport ResampleFilter *AcquireResampleFilter(const Image *image, 208 ExceptionInfo *exception) 209{ 210 register ResampleFilter 211 *resample_filter; 212 213 assert(image != (Image *) NULL); 214 assert(image->signature == MagickCoreSignature); 215 if (image->debug != MagickFalse) 216 (void) LogMagickEvent(TraceEvent,GetMagickModule(),"%s",image->filename); 217 assert(exception != (ExceptionInfo *) NULL); 218 assert(exception->signature == MagickCoreSignature); 219 resample_filter=(ResampleFilter *) AcquireMagickMemory(sizeof( 220 *resample_filter)); 221 if (resample_filter == (ResampleFilter *) NULL) 222 ThrowFatalException(ResourceLimitFatalError,"MemoryAllocationFailed"); 223 (void) ResetMagickMemory(resample_filter,0,sizeof(*resample_filter)); 224 resample_filter->exception=exception; 225 resample_filter->image=ReferenceImage((Image *) image); 226 resample_filter->view=AcquireVirtualCacheView(resample_filter->image, 227 exception); 228 resample_filter->debug=IsEventLogging(); 229 resample_filter->image_area=(ssize_t) (image->columns*image->rows); 230 resample_filter->average_defined=MagickFalse; 231 resample_filter->signature=MagickCoreSignature; 232 SetResampleFilter(resample_filter,image->filter); 233 (void) SetResampleFilterInterpolateMethod(resample_filter,image->interpolate); 234 (void) SetResampleFilterVirtualPixelMethod(resample_filter, 235 GetImageVirtualPixelMethod(image)); 236 return(resample_filter); 237} 238 239/* 240%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 241% % 242% % 243% % 244% D e s t r o y R e s a m p l e I n f o % 245% % 246% % 247% % 248%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 249% 250% DestroyResampleFilter() finalizes and cleans up the resampling 251% resample_filter as returned by AcquireResampleFilter(), freeing any memory 252% or other information as needed. 253% 254% The format of the DestroyResampleFilter method is: 255% 256% ResampleFilter *DestroyResampleFilter(ResampleFilter *resample_filter) 257% 258% A description of each parameter follows: 259% 260% o resample_filter: resampling information structure 261% 262*/ 263MagickExport ResampleFilter *DestroyResampleFilter( 264 ResampleFilter *resample_filter) 265{ 266 assert(resample_filter != (ResampleFilter *) NULL); 267 assert(resample_filter->signature == MagickCoreSignature); 268 assert(resample_filter->image != (Image *) NULL); 269 if (resample_filter->debug != MagickFalse) 270 (void) LogMagickEvent(TraceEvent,GetMagickModule(),"%s", 271 resample_filter->image->filename); 272 resample_filter->view=DestroyCacheView(resample_filter->view); 273 resample_filter->image=DestroyImage(resample_filter->image); 274#if ! FILTER_LUT 275 resample_filter->filter_def=DestroyResizeFilter(resample_filter->filter_def); 276#endif 277 resample_filter->signature=(~MagickCoreSignature); 278 resample_filter=(ResampleFilter *) RelinquishMagickMemory(resample_filter); 279 return(resample_filter); 280} 281 282/* 283%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 284% % 285% % 286% % 287% R e s a m p l e P i x e l C o l o r % 288% % 289% % 290% % 291%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 292% 293% ResamplePixelColor() samples the pixel values surrounding the location 294% given using an elliptical weighted average, at the scale previously 295% calculated, and in the most efficent manner possible for the 296% VirtualPixelMethod setting. 297% 298% The format of the ResamplePixelColor method is: 299% 300% MagickBooleanType ResamplePixelColor(ResampleFilter *resample_filter, 301% const double u0,const double v0,PixelInfo *pixel, 302% ExceptionInfo *exception) 303% 304% A description of each parameter follows: 305% 306% o resample_filter: the resample filter. 307% 308% o u0,v0: A double representing the center of the area to resample, 309% The distortion transformed transformed x,y coordinate. 310% 311% o pixel: the resampled pixel is returned here. 312% 313% o exception: return any errors or warnings in this structure. 314% 315*/ 316MagickExport MagickBooleanType ResamplePixelColor( 317 ResampleFilter *resample_filter,const double u0,const double v0, 318 PixelInfo *pixel,ExceptionInfo *exception) 319{ 320 MagickBooleanType 321 status; 322 323 ssize_t u,v, v1, v2, uw, hit; 324 double u1; 325 double U,V,Q,DQ,DDQ; 326 double divisor_c,divisor_m; 327 register double weight; 328 register const Quantum *pixels; 329 assert(resample_filter != (ResampleFilter *) NULL); 330 assert(resample_filter->signature == MagickCoreSignature); 331 332 status=MagickTrue; 333 /* GetPixelInfo(resample_filter->image,pixel); */ 334 if ( resample_filter->do_interpolate ) { 335 status=InterpolatePixelInfo(resample_filter->image,resample_filter->view, 336 resample_filter->interpolate,u0,v0,pixel,resample_filter->exception); 337 return(status); 338 } 339 340#if DEBUG_ELLIPSE 341 (void) FormatLocaleFile(stderr, "u0=%lf; v0=%lf;\n", u0, v0); 342#endif 343 344 /* 345 Does resample area Miss the image Proper? 346 If and that area a simple solid color - then simply return that color! 347 This saves a lot of calculation when resampling outside the bounds of 348 the source image. 349 350 However it probably should be expanded to image bounds plus the filters 351 scaled support size. 352 */ 353 hit = 0; 354 switch ( resample_filter->virtual_pixel ) { 355 case BackgroundVirtualPixelMethod: 356 case TransparentVirtualPixelMethod: 357 case BlackVirtualPixelMethod: 358 case GrayVirtualPixelMethod: 359 case WhiteVirtualPixelMethod: 360 case MaskVirtualPixelMethod: 361 if ( resample_filter->limit_reached 362 || u0 + resample_filter->Ulimit < 0.0 363 || u0 - resample_filter->Ulimit > (double) resample_filter->image->columns-1.0 364 || v0 + resample_filter->Vlimit < 0.0 365 || v0 - resample_filter->Vlimit > (double) resample_filter->image->rows-1.0 366 ) 367 hit++; 368 break; 369 370 case UndefinedVirtualPixelMethod: 371 case EdgeVirtualPixelMethod: 372 if ( ( u0 + resample_filter->Ulimit < 0.0 && v0 + resample_filter->Vlimit < 0.0 ) 373 || ( u0 + resample_filter->Ulimit < 0.0 374 && v0 - resample_filter->Vlimit > (double) resample_filter->image->rows-1.0 ) 375 || ( u0 - resample_filter->Ulimit > (double) resample_filter->image->columns-1.0 376 && v0 + resample_filter->Vlimit < 0.0 ) 377 || ( u0 - resample_filter->Ulimit > (double) resample_filter->image->columns-1.0 378 && v0 - resample_filter->Vlimit > (double) resample_filter->image->rows-1.0 ) 379 ) 380 hit++; 381 break; 382 case HorizontalTileVirtualPixelMethod: 383 if ( v0 + resample_filter->Vlimit < 0.0 384 || v0 - resample_filter->Vlimit > (double) resample_filter->image->rows-1.0 385 ) 386 hit++; /* outside the horizontally tiled images. */ 387 break; 388 case VerticalTileVirtualPixelMethod: 389 if ( u0 + resample_filter->Ulimit < 0.0 390 || u0 - resample_filter->Ulimit > (double) resample_filter->image->columns-1.0 391 ) 392 hit++; /* outside the vertically tiled images. */ 393 break; 394 case DitherVirtualPixelMethod: 395 if ( ( u0 + resample_filter->Ulimit < -32.0 && v0 + resample_filter->Vlimit < -32.0 ) 396 || ( u0 + resample_filter->Ulimit < -32.0 397 && v0 - resample_filter->Vlimit > (double) resample_filter->image->rows+31.0 ) 398 || ( u0 - resample_filter->Ulimit > (double) resample_filter->image->columns+31.0 399 && v0 + resample_filter->Vlimit < -32.0 ) 400 || ( u0 - resample_filter->Ulimit > (double) resample_filter->image->columns+31.0 401 && v0 - resample_filter->Vlimit > (double) resample_filter->image->rows+31.0 ) 402 ) 403 hit++; 404 break; 405 case TileVirtualPixelMethod: 406 case MirrorVirtualPixelMethod: 407 case RandomVirtualPixelMethod: 408 case HorizontalTileEdgeVirtualPixelMethod: 409 case VerticalTileEdgeVirtualPixelMethod: 410 case CheckerTileVirtualPixelMethod: 411 /* resampling of area is always needed - no VP limits */ 412 break; 413 } 414 if ( hit ) { 415 /* The area being resampled is simply a solid color 416 * just return a single lookup color. 417 * 418 * Should this return the users requested interpolated color? 419 */ 420 status=InterpolatePixelInfo(resample_filter->image,resample_filter->view, 421 IntegerInterpolatePixel,u0,v0,pixel,resample_filter->exception); 422 return(status); 423 } 424 425 /* 426 When Scaling limits reached, return an 'averaged' result. 427 */ 428 if ( resample_filter->limit_reached ) { 429 switch ( resample_filter->virtual_pixel ) { 430 /* This is always handled by the above, so no need. 431 case BackgroundVirtualPixelMethod: 432 case ConstantVirtualPixelMethod: 433 case TransparentVirtualPixelMethod: 434 case GrayVirtualPixelMethod, 435 case WhiteVirtualPixelMethod 436 case MaskVirtualPixelMethod: 437 */ 438 case UndefinedVirtualPixelMethod: 439 case EdgeVirtualPixelMethod: 440 case DitherVirtualPixelMethod: 441 case HorizontalTileEdgeVirtualPixelMethod: 442 case VerticalTileEdgeVirtualPixelMethod: 443 /* We need an average edge pixel, from the correct edge! 444 How should I calculate an average edge color? 445 Just returning an averaged neighbourhood, 446 works well in general, but falls down for TileEdge methods. 447 This needs to be done properly!!!!!! 448 */ 449 status=InterpolatePixelInfo(resample_filter->image, 450 resample_filter->view,AverageInterpolatePixel,u0,v0,pixel, 451 resample_filter->exception); 452 break; 453 case HorizontalTileVirtualPixelMethod: 454 case VerticalTileVirtualPixelMethod: 455 /* just return the background pixel - Is there more direct way? */ 456 status=InterpolatePixelInfo(resample_filter->image, 457 resample_filter->view,IntegerInterpolatePixel,-1.0,-1.0,pixel, 458 resample_filter->exception); 459 break; 460 case TileVirtualPixelMethod: 461 case MirrorVirtualPixelMethod: 462 case RandomVirtualPixelMethod: 463 case CheckerTileVirtualPixelMethod: 464 default: 465 /* generate a average color of the WHOLE image */ 466 if ( resample_filter->average_defined == MagickFalse ) { 467 Image 468 *average_image; 469 470 CacheView 471 *average_view; 472 473 GetPixelInfo(resample_filter->image,(PixelInfo *) 474 &resample_filter->average_pixel); 475 resample_filter->average_defined=MagickTrue; 476 477 /* Try to get an averaged pixel color of whole image */ 478 average_image=ResizeImage(resample_filter->image,1,1,BoxFilter, 479 resample_filter->exception); 480 if (average_image == (Image *) NULL) 481 { 482 *pixel=resample_filter->average_pixel; /* FAILED */ 483 break; 484 } 485 average_view=AcquireVirtualCacheView(average_image,exception); 486 pixels=GetCacheViewVirtualPixels(average_view,0,0,1,1, 487 resample_filter->exception); 488 if (pixels == (const Quantum *) NULL) { 489 average_view=DestroyCacheView(average_view); 490 average_image=DestroyImage(average_image); 491 *pixel=resample_filter->average_pixel; /* FAILED */ 492 break; 493 } 494 GetPixelInfoPixel(resample_filter->image,pixels, 495 &(resample_filter->average_pixel)); 496 average_view=DestroyCacheView(average_view); 497 average_image=DestroyImage(average_image); 498 499 if ( resample_filter->virtual_pixel == CheckerTileVirtualPixelMethod ) 500 { 501 /* CheckerTile is a alpha blend of the image's average pixel 502 color and the current background color */ 503 504 /* image's average pixel color */ 505 weight = QuantumScale*((double) 506 resample_filter->average_pixel.alpha); 507 resample_filter->average_pixel.red *= weight; 508 resample_filter->average_pixel.green *= weight; 509 resample_filter->average_pixel.blue *= weight; 510 divisor_c = weight; 511 512 /* background color */ 513 weight = QuantumScale*((double) 514 resample_filter->image->background_color.alpha); 515 resample_filter->average_pixel.red += 516 weight*resample_filter->image->background_color.red; 517 resample_filter->average_pixel.green += 518 weight*resample_filter->image->background_color.green; 519 resample_filter->average_pixel.blue += 520 weight*resample_filter->image->background_color.blue; 521 resample_filter->average_pixel.alpha += 522 resample_filter->image->background_color.alpha; 523 divisor_c += weight; 524 525 /* alpha blend */ 526 resample_filter->average_pixel.red /= divisor_c; 527 resample_filter->average_pixel.green /= divisor_c; 528 resample_filter->average_pixel.blue /= divisor_c; 529 resample_filter->average_pixel.alpha /= 2; /* 50% blend */ 530 531 } 532 } 533 *pixel=resample_filter->average_pixel; 534 break; 535 } 536 return(status); 537 } 538 539 /* 540 Initialize weighted average data collection 541 */ 542 hit = 0; 543 divisor_c = 0.0; 544 divisor_m = 0.0; 545 pixel->red = pixel->green = pixel->blue = 0.0; 546 if (pixel->colorspace == CMYKColorspace) 547 pixel->black = 0.0; 548 if (pixel->alpha_trait != UndefinedPixelTrait) 549 pixel->alpha = 0.0; 550 551 /* 552 Determine the parellelogram bounding box fitted to the ellipse 553 centered at u0,v0. This area is bounding by the lines... 554 */ 555 v1 = (ssize_t)ceil(v0 - resample_filter->Vlimit); /* range of scan lines */ 556 v2 = (ssize_t)floor(v0 + resample_filter->Vlimit); 557 558 /* scan line start and width accross the parallelogram */ 559 u1 = u0 + (v1-v0)*resample_filter->slope - resample_filter->Uwidth; 560 uw = (ssize_t)(2.0*resample_filter->Uwidth)+1; 561 562#if DEBUG_ELLIPSE 563 (void) FormatLocaleFile(stderr, "v1=%ld; v2=%ld\n", (long)v1, (long)v2); 564 (void) FormatLocaleFile(stderr, "u1=%ld; uw=%ld\n", (long)u1, (long)uw); 565#else 566# define DEBUG_HIT_MISS 0 /* only valid if DEBUG_ELLIPSE is enabled */ 567#endif 568 569 /* 570 Do weighted resampling of all pixels, within the scaled ellipse, 571 bound by a Parellelogram fitted to the ellipse. 572 */ 573 DDQ = 2*resample_filter->A; 574 for( v=v1; v<=v2; v++ ) { 575#if DEBUG_HIT_MISS 576 long uu = ceil(u1); /* actual pixel location (for debug only) */ 577 (void) FormatLocaleFile(stderr, "# scan line from pixel %ld, %ld\n", (long)uu, (long)v); 578#endif 579 u = (ssize_t)ceil(u1); /* first pixel in scanline */ 580 u1 += resample_filter->slope; /* start of next scan line */ 581 582 583 /* location of this first pixel, relative to u0,v0 */ 584 U = (double)u-u0; 585 V = (double)v-v0; 586 587 /* Q = ellipse quotent ( if Q<F then pixel is inside ellipse) */ 588 Q = (resample_filter->A*U + resample_filter->B*V)*U + resample_filter->C*V*V; 589 DQ = resample_filter->A*(2.0*U+1) + resample_filter->B*V; 590 591 /* get the scanline of pixels for this v */ 592 pixels=GetCacheViewVirtualPixels(resample_filter->view,u,v,(size_t) uw, 593 1,resample_filter->exception); 594 if (pixels == (const Quantum *) NULL) 595 return(MagickFalse); 596 597 /* count up the weighted pixel colors */ 598 for( u=0; u<uw; u++ ) { 599#if FILTER_LUT 600 /* Note that the ellipse has been pre-scaled so F = WLUT_WIDTH */ 601 if ( Q < (double)WLUT_WIDTH ) { 602 weight = resample_filter->filter_lut[(int)Q]; 603#else 604 /* Note that the ellipse has been pre-scaled so F = support^2 */ 605 if ( Q < (double)resample_filter->F ) { 606 weight = GetResizeFilterWeight(resample_filter->filter_def, 607 sqrt(Q)); /* a SquareRoot! Arrggghhhhh... */ 608#endif 609 610 pixel->alpha += weight*GetPixelAlpha(resample_filter->image,pixels); 611 divisor_m += weight; 612 613 if (pixel->alpha_trait != UndefinedPixelTrait) 614 weight *= QuantumScale*((double) GetPixelAlpha(resample_filter->image,pixels)); 615 pixel->red += weight*GetPixelRed(resample_filter->image,pixels); 616 pixel->green += weight*GetPixelGreen(resample_filter->image,pixels); 617 pixel->blue += weight*GetPixelBlue(resample_filter->image,pixels); 618 if (pixel->colorspace == CMYKColorspace) 619 pixel->black += weight*GetPixelBlack(resample_filter->image,pixels); 620 divisor_c += weight; 621 622 hit++; 623#if DEBUG_HIT_MISS 624 /* mark the pixel according to hit/miss of the ellipse */ 625 (void) FormatLocaleFile(stderr, "set arrow from %lf,%lf to %lf,%lf nohead ls 3\n", 626 (long)uu-.1,(double)v-.1,(long)uu+.1,(long)v+.1); 627 (void) FormatLocaleFile(stderr, "set arrow from %lf,%lf to %lf,%lf nohead ls 3\n", 628 (long)uu+.1,(double)v-.1,(long)uu-.1,(long)v+.1); 629 } else { 630 (void) FormatLocaleFile(stderr, "set arrow from %lf,%lf to %lf,%lf nohead ls 1\n", 631 (long)uu-.1,(double)v-.1,(long)uu+.1,(long)v+.1); 632 (void) FormatLocaleFile(stderr, "set arrow from %lf,%lf to %lf,%lf nohead ls 1\n", 633 (long)uu+.1,(double)v-.1,(long)uu-.1,(long)v+.1); 634 } 635 uu++; 636#else 637 } 638#endif 639 pixels+=GetPixelChannels(resample_filter->image); 640 Q += DQ; 641 DQ += DDQ; 642 } 643 } 644#if DEBUG_ELLIPSE 645 (void) FormatLocaleFile(stderr, "Hit=%ld; Total=%ld;\n", (long)hit, (long)uw*(v2-v1) ); 646#endif 647 648 /* 649 Result sanity check -- this should NOT happen 650 */ 651 if ( hit == 0 || divisor_m <= MagickEpsilon || divisor_c <= MagickEpsilon ) { 652 /* not enough pixels, or bad weighting in resampling, 653 resort to direct interpolation */ 654#if DEBUG_NO_PIXEL_HIT 655 pixel->alpha = pixel->red = pixel->green = pixel->blue = 0; 656 pixel->red = QuantumRange; /* show pixels for which EWA fails */ 657#else 658 status=InterpolatePixelInfo(resample_filter->image, 659 resample_filter->view,resample_filter->interpolate,u0,v0,pixel, 660 resample_filter->exception); 661#endif 662 return status; 663 } 664 665 /* 666 Finialize results of resampling 667 */ 668 divisor_m = 1.0/divisor_m; 669 if (pixel->alpha_trait != UndefinedPixelTrait) 670 pixel->alpha = (double) ClampToQuantum(divisor_m*pixel->alpha); 671 divisor_c = 1.0/divisor_c; 672 pixel->red = (double) ClampToQuantum(divisor_c*pixel->red); 673 pixel->green = (double) ClampToQuantum(divisor_c*pixel->green); 674 pixel->blue = (double) ClampToQuantum(divisor_c*pixel->blue); 675 if (pixel->colorspace == CMYKColorspace) 676 pixel->black = (double) ClampToQuantum(divisor_c*pixel->black); 677 return(MagickTrue); 678} 679 680#if EWA && EWA_CLAMP 681/* 682%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 683% % 684% % 685% % 686- C l a m p U p A x e s % 687% % 688% % 689% % 690%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 691% 692% ClampUpAxes() function converts the input vectors into a major and 693% minor axis unit vectors, and their magnitude. This allows us to 694% ensure that the ellipse generated is never smaller than the unit 695% circle and thus never too small for use in EWA resampling. 696% 697% This purely mathematical 'magic' was provided by Professor Nicolas 698% Robidoux and his Masters student Chantal Racette. 699% 700% Reference: "We Recommend Singular Value Decomposition", David Austin 701% http://www.ams.org/samplings/feature-column/fcarc-svd 702% 703% By generating major and minor axis vectors, we can actually use the 704% ellipse in its "canonical form", by remapping the dx,dy of the 705% sampled point into distances along the major and minor axis unit 706% vectors. 707% 708% Reference: http://en.wikipedia.org/wiki/Ellipse#Canonical_form 709*/ 710static inline void ClampUpAxes(const double dux, 711 const double dvx, 712 const double duy, 713 const double dvy, 714 double *major_mag, 715 double *minor_mag, 716 double *major_unit_x, 717 double *major_unit_y, 718 double *minor_unit_x, 719 double *minor_unit_y) 720{ 721 /* 722 * ClampUpAxes takes an input 2x2 matrix 723 * 724 * [ a b ] = [ dux duy ] 725 * [ c d ] = [ dvx dvy ] 726 * 727 * and computes from it the major and minor axis vectors [major_x, 728 * major_y] and [minor_x,minor_y] of the smallest ellipse containing 729 * both the unit disk and the ellipse which is the image of the unit 730 * disk by the linear transformation 731 * 732 * [ dux duy ] [S] = [s] 733 * [ dvx dvy ] [T] = [t] 734 * 735 * (The vector [S,T] is the difference between a position in output 736 * space and [X,Y]; the vector [s,t] is the difference between a 737 * position in input space and [x,y].) 738 */ 739 /* 740 * Output: 741 * 742 * major_mag is the half-length of the major axis of the "new" 743 * ellipse. 744 * 745 * minor_mag is the half-length of the minor axis of the "new" 746 * ellipse. 747 * 748 * major_unit_x is the x-coordinate of the major axis direction vector 749 * of both the "old" and "new" ellipses. 750 * 751 * major_unit_y is the y-coordinate of the major axis direction vector. 752 * 753 * minor_unit_x is the x-coordinate of the minor axis direction vector. 754 * 755 * minor_unit_y is the y-coordinate of the minor axis direction vector. 756 * 757 * Unit vectors are useful for computing projections, in particular, 758 * to compute the distance between a point in output space and the 759 * center of a unit disk in output space, using the position of the 760 * corresponding point [s,t] in input space. Following the clamping, 761 * the square of this distance is 762 * 763 * ( ( s * major_unit_x + t * major_unit_y ) / major_mag )^2 764 * + 765 * ( ( s * minor_unit_x + t * minor_unit_y ) / minor_mag )^2 766 * 767 * If such distances will be computed for many [s,t]'s, it makes 768 * sense to actually compute the reciprocal of major_mag and 769 * minor_mag and multiply them by the above unit lengths. 770 * 771 * Now, if you want to modify the input pair of tangent vectors so 772 * that it defines the modified ellipse, all you have to do is set 773 * 774 * newdux = major_mag * major_unit_x 775 * newdvx = major_mag * major_unit_y 776 * newduy = minor_mag * minor_unit_x = minor_mag * -major_unit_y 777 * newdvy = minor_mag * minor_unit_y = minor_mag * major_unit_x 778 * 779 * and use these tangent vectors as if they were the original ones. 780 * Usually, this is a drastic change in the tangent vectors even if 781 * the singular values are not clamped; for example, the minor axis 782 * vector always points in a direction which is 90 degrees 783 * counterclockwise from the direction of the major axis vector. 784 */ 785 /* 786 * Discussion: 787 * 788 * GOAL: Fix things so that the pullback, in input space, of a disk 789 * of radius r in output space is an ellipse which contains, at 790 * least, a disc of radius r. (Make this hold for any r>0.) 791 * 792 * ESSENCE OF THE METHOD: Compute the product of the first two 793 * factors of an SVD of the linear transformation defining the 794 * ellipse and make sure that both its columns have norm at least 1. 795 * Because rotations and reflexions map disks to themselves, it is 796 * not necessary to compute the third (rightmost) factor of the SVD. 797 * 798 * DETAILS: Find the singular values and (unit) left singular 799 * vectors of Jinv, clampling up the singular values to 1, and 800 * multiply the unit left singular vectors by the new singular 801 * values in order to get the minor and major ellipse axis vectors. 802 * 803 * Image resampling context: 804 * 805 * The Jacobian matrix of the transformation at the output point 806 * under consideration is defined as follows: 807 * 808 * Consider the transformation (x,y) -> (X,Y) from input locations 809 * to output locations. (Anthony Thyssen, elsewhere in resample.c, 810 * uses the notation (u,v) -> (x,y).) 811 * 812 * The Jacobian matrix of the transformation at (x,y) is equal to 813 * 814 * J = [ A, B ] = [ dX/dx, dX/dy ] 815 * [ C, D ] [ dY/dx, dY/dy ] 816 * 817 * that is, the vector [A,C] is the tangent vector corresponding to 818 * input changes in the horizontal direction, and the vector [B,D] 819 * is the tangent vector corresponding to input changes in the 820 * vertical direction. 821 * 822 * In the context of resampling, it is natural to use the inverse 823 * Jacobian matrix Jinv because resampling is generally performed by 824 * pulling pixel locations in the output image back to locations in 825 * the input image. Jinv is 826 * 827 * Jinv = [ a, b ] = [ dx/dX, dx/dY ] 828 * [ c, d ] [ dy/dX, dy/dY ] 829 * 830 * Note: Jinv can be computed from J with the following matrix 831 * formula: 832 * 833 * Jinv = 1/(A*D-B*C) [ D, -B ] 834 * [ -C, A ] 835 * 836 * What we do is modify Jinv so that it generates an ellipse which 837 * is as close as possible to the original but which contains the 838 * unit disk. This can be accomplished as follows: 839 * 840 * Let 841 * 842 * Jinv = U Sigma V^T 843 * 844 * be an SVD decomposition of Jinv. (The SVD is not unique, but the 845 * final ellipse does not depend on the particular SVD.) 846 * 847 * We could clamp up the entries of the diagonal matrix Sigma so 848 * that they are at least 1, and then set 849 * 850 * Jinv = U newSigma V^T. 851 * 852 * However, we do not need to compute V for the following reason: 853 * V^T is an orthogonal matrix (that is, it represents a combination 854 * of rotations and reflexions) so that it maps the unit circle to 855 * itself. For this reason, the exact value of V does not affect the 856 * final ellipse, and we can choose V to be the identity 857 * matrix. This gives 858 * 859 * Jinv = U newSigma. 860 * 861 * In the end, we return the two diagonal entries of newSigma 862 * together with the two columns of U. 863 */ 864 /* 865 * ClampUpAxes was written by Nicolas Robidoux and Chantal Racette 866 * of Laurentian University with insightful suggestions from Anthony 867 * Thyssen and funding from the National Science and Engineering 868 * Research Council of Canada. It is distinguished from its 869 * predecessors by its efficient handling of degenerate cases. 870 * 871 * The idea of clamping up the EWA ellipse's major and minor axes so 872 * that the result contains the reconstruction kernel filter support 873 * is taken from Andreas Gustaffson's Masters thesis "Interactive 874 * Image Warping", Helsinki University of Technology, Faculty of 875 * Information Technology, 59 pages, 1993 (see Section 3.6). 876 * 877 * The use of the SVD to clamp up the singular values of the 878 * Jacobian matrix of the pullback transformation for EWA resampling 879 * is taken from the astrophysicist Craig DeForest. It is 880 * implemented in his PDL::Transform code (PDL = Perl Data 881 * Language). 882 */ 883 const double a = dux; 884 const double b = duy; 885 const double c = dvx; 886 const double d = dvy; 887 /* 888 * n is the matrix Jinv * transpose(Jinv). Eigenvalues of n are the 889 * squares of the singular values of Jinv. 890 */ 891 const double aa = a*a; 892 const double bb = b*b; 893 const double cc = c*c; 894 const double dd = d*d; 895 /* 896 * Eigenvectors of n are left singular vectors of Jinv. 897 */ 898 const double n11 = aa+bb; 899 const double n12 = a*c+b*d; 900 const double n21 = n12; 901 const double n22 = cc+dd; 902 const double det = a*d-b*c; 903 const double twice_det = det+det; 904 const double frobenius_squared = n11+n22; 905 const double discriminant = 906 (frobenius_squared+twice_det)*(frobenius_squared-twice_det); 907 /* 908 * In exact arithmetic, discriminant can't be negative. In floating 909 * point, it can, because of the bad conditioning of SVD 910 * decompositions done through the associated normal matrix. 911 */ 912 const double sqrt_discriminant = 913 sqrt(discriminant > 0.0 ? discriminant : 0.0); 914 /* 915 * s1 is the largest singular value of the inverse Jacobian 916 * matrix. In other words, its reciprocal is the smallest singular 917 * value of the Jacobian matrix itself. 918 * If s1 = 0, both singular values are 0, and any orthogonal pair of 919 * left and right factors produces a singular decomposition of Jinv. 920 */ 921 /* 922 * Initially, we only compute the squares of the singular values. 923 */ 924 const double s1s1 = 0.5*(frobenius_squared+sqrt_discriminant); 925 /* 926 * s2 the smallest singular value of the inverse Jacobian 927 * matrix. Its reciprocal is the largest singular value of the 928 * Jacobian matrix itself. 929 */ 930 const double s2s2 = 0.5*(frobenius_squared-sqrt_discriminant); 931 const double s1s1minusn11 = s1s1-n11; 932 const double s1s1minusn22 = s1s1-n22; 933 /* 934 * u1, the first column of the U factor of a singular decomposition 935 * of Jinv, is a (non-normalized) left singular vector corresponding 936 * to s1. It has entries u11 and u21. We compute u1 from the fact 937 * that it is an eigenvector of n corresponding to the eigenvalue 938 * s1^2. 939 */ 940 const double s1s1minusn11_squared = s1s1minusn11*s1s1minusn11; 941 const double s1s1minusn22_squared = s1s1minusn22*s1s1minusn22; 942 /* 943 * The following selects the largest row of n-s1^2 I as the one 944 * which is used to find the eigenvector. If both s1^2-n11 and 945 * s1^2-n22 are zero, n-s1^2 I is the zero matrix. In that case, 946 * any vector is an eigenvector; in addition, norm below is equal to 947 * zero, and, in exact arithmetic, this is the only case in which 948 * norm = 0. So, setting u1 to the simple but arbitrary vector [1,0] 949 * if norm = 0 safely takes care of all cases. 950 */ 951 const double temp_u11 = 952 ( (s1s1minusn11_squared>=s1s1minusn22_squared) ? n12 : s1s1minusn22 ); 953 const double temp_u21 = 954 ( (s1s1minusn11_squared>=s1s1minusn22_squared) ? s1s1minusn11 : n21 ); 955 const double norm = sqrt(temp_u11*temp_u11+temp_u21*temp_u21); 956 /* 957 * Finalize the entries of first left singular vector (associated 958 * with the largest singular value). 959 */ 960 const double u11 = ( (norm>0.0) ? temp_u11/norm : 1.0 ); 961 const double u21 = ( (norm>0.0) ? temp_u21/norm : 0.0 ); 962 /* 963 * Clamp the singular values up to 1. 964 */ 965 *major_mag = ( (s1s1<=1.0) ? 1.0 : sqrt(s1s1) ); 966 *minor_mag = ( (s2s2<=1.0) ? 1.0 : sqrt(s2s2) ); 967 /* 968 * Return the unit major and minor axis direction vectors. 969 */ 970 *major_unit_x = u11; 971 *major_unit_y = u21; 972 *minor_unit_x = -u21; 973 *minor_unit_y = u11; 974} 975 976#endif 977/* 978%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 979% % 980% % 981% % 982% S c a l e R e s a m p l e F i l t e r % 983% % 984% % 985% % 986%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 987% 988% ScaleResampleFilter() does all the calculations needed to resample an image 989% at a specific scale, defined by two scaling vectors. This not using 990% a orthogonal scaling, but two distorted scaling vectors, to allow the 991% generation of a angled ellipse. 992% 993% As only two deritive scaling vectors are used the center of the ellipse 994% must be the center of the lookup. That is any curvature that the 995% distortion may produce is discounted. 996% 997% The input vectors are produced by either finding the derivitives of the 998% distortion function, or the partial derivitives from a distortion mapping. 999% They do not need to be the orthogonal dx,dy scaling vectors, but can be 1000% calculated from other derivatives. For example you could use dr,da/r 1001% polar coordinate vector scaling vectors 1002% 1003% If u,v = DistortEquation(x,y) OR u = Fu(x,y); v = Fv(x,y) 1004% Then the scaling vectors are determined from the deritives... 1005% du/dx, dv/dx and du/dy, dv/dy 1006% If the resulting scaling vectors is othogonally aligned then... 1007% dv/dx = 0 and du/dy = 0 1008% Producing an othogonally alligned ellipse in source space for the area to 1009% be resampled. 1010% 1011% Note that scaling vectors are different to argument order. Argument order 1012% is the general order the deritives are extracted from the distortion 1013% equations, and not the scaling vectors. As such the middle two vaules 1014% may be swapped from what you expect. Caution is advised. 1015% 1016% WARNING: It is assumed that any SetResampleFilter() method call will 1017% always be performed before the ScaleResampleFilter() method, so that the 1018% size of the ellipse will match the support for the resampling filter being 1019% used. 1020% 1021% The format of the ScaleResampleFilter method is: 1022% 1023% void ScaleResampleFilter(const ResampleFilter *resample_filter, 1024% const double dux,const double duy,const double dvx,const double dvy) 1025% 1026% A description of each parameter follows: 1027% 1028% o resample_filter: the resampling resample_filterrmation defining the 1029% image being resampled 1030% 1031% o dux,duy,dvx,dvy: 1032% The deritives or scaling vectors defining the EWA ellipse. 1033% NOTE: watch the order, which is based on the order deritives 1034% are usally determined from distortion equations (see above). 1035% The middle two values may need to be swapped if you are thinking 1036% in terms of scaling vectors. 1037% 1038*/ 1039MagickExport void ScaleResampleFilter(ResampleFilter *resample_filter, 1040 const double dux,const double duy,const double dvx,const double dvy) 1041{ 1042 double A,B,C,F; 1043 1044 assert(resample_filter != (ResampleFilter *) NULL); 1045 assert(resample_filter->signature == MagickCoreSignature); 1046 1047 resample_filter->limit_reached = MagickFalse; 1048 1049 /* A 'point' filter forces use of interpolation instead of area sampling */ 1050 if ( resample_filter->filter == PointFilter ) 1051 return; /* EWA turned off - nothing to do */ 1052 1053#if DEBUG_ELLIPSE 1054 (void) FormatLocaleFile(stderr, "# -----\n" ); 1055 (void) FormatLocaleFile(stderr, "dux=%lf; dvx=%lf; duy=%lf; dvy=%lf;\n", 1056 dux, dvx, duy, dvy); 1057#endif 1058 1059 /* Find Ellipse Coefficents such that 1060 A*u^2 + B*u*v + C*v^2 = F 1061 With u,v relative to point around which we are resampling. 1062 And the given scaling dx,dy vectors in u,v space 1063 du/dx,dv/dx and du/dy,dv/dy 1064 */ 1065#if EWA 1066 /* Direct conversion of derivatives into elliptical coefficients 1067 However when magnifying images, the scaling vectors will be small 1068 resulting in a ellipse that is too small to sample properly. 1069 As such we need to clamp the major/minor axis to a minumum of 1.0 1070 to prevent it getting too small. 1071 */ 1072#if EWA_CLAMP 1073 { double major_mag, 1074 minor_mag, 1075 major_x, 1076 major_y, 1077 minor_x, 1078 minor_y; 1079 1080 ClampUpAxes(dux,dvx,duy,dvy, &major_mag, &minor_mag, 1081 &major_x, &major_y, &minor_x, &minor_y); 1082 major_x *= major_mag; major_y *= major_mag; 1083 minor_x *= minor_mag; minor_y *= minor_mag; 1084#if DEBUG_ELLIPSE 1085 (void) FormatLocaleFile(stderr, "major_x=%lf; major_y=%lf; minor_x=%lf; minor_y=%lf;\n", 1086 major_x, major_y, minor_x, minor_y); 1087#endif 1088 A = major_y*major_y+minor_y*minor_y; 1089 B = -2.0*(major_x*major_y+minor_x*minor_y); 1090 C = major_x*major_x+minor_x*minor_x; 1091 F = major_mag*minor_mag; 1092 F *= F; /* square it */ 1093 } 1094#else /* raw unclamped EWA */ 1095 A = dvx*dvx+dvy*dvy; 1096 B = -2.0*(dux*dvx+duy*dvy); 1097 C = dux*dux+duy*duy; 1098 F = dux*dvy-duy*dvx; 1099 F *= F; /* square it */ 1100#endif /* EWA_CLAMP */ 1101 1102#else /* HQ_EWA */ 1103 /* 1104 This Paul Heckbert's "Higher Quality EWA" formula, from page 60 in his 1105 thesis, which adds a unit circle to the elliptical area so as to do both 1106 Reconstruction and Prefiltering of the pixels in the resampling. It also 1107 means it is always likely to have at least 4 pixels within the area of the 1108 ellipse, for weighted averaging. No scaling will result with F == 4.0 and 1109 a circle of radius 2.0, and F smaller than this means magnification is 1110 being used. 1111 1112 NOTE: This method produces a very blury result at near unity scale while 1113 producing perfect results for strong minitification and magnifications. 1114 1115 However filter support is fixed to 2.0 (no good for Windowed Sinc filters) 1116 */ 1117 A = dvx*dvx+dvy*dvy+1; 1118 B = -2.0*(dux*dvx+duy*dvy); 1119 C = dux*dux+duy*duy+1; 1120 F = A*C - B*B/4; 1121#endif 1122 1123#if DEBUG_ELLIPSE 1124 (void) FormatLocaleFile(stderr, "A=%lf; B=%lf; C=%lf; F=%lf\n", A,B,C,F); 1125 1126 /* Figure out the various information directly about the ellipse. 1127 This information currently not needed at this time, but may be 1128 needed later for better limit determination. 1129 1130 It is also good to have as a record for future debugging 1131 */ 1132 { double alpha, beta, gamma, Major, Minor; 1133 double Eccentricity, Ellipse_Area, Ellipse_Angle; 1134 1135 alpha = A+C; 1136 beta = A-C; 1137 gamma = sqrt(beta*beta + B*B ); 1138 1139 if ( alpha - gamma <= MagickEpsilon ) 1140 Major=MagickMaximumValue; 1141 else 1142 Major=sqrt(2*F/(alpha - gamma)); 1143 Minor = sqrt(2*F/(alpha + gamma)); 1144 1145 (void) FormatLocaleFile(stderr, "# Major=%lf; Minor=%lf\n", Major, Minor ); 1146 1147 /* other information about ellipse include... */ 1148 Eccentricity = Major/Minor; 1149 Ellipse_Area = MagickPI*Major*Minor; 1150 Ellipse_Angle = atan2(B, A-C); 1151 1152 (void) FormatLocaleFile(stderr, "# Angle=%lf Area=%lf\n", 1153 (double) RadiansToDegrees(Ellipse_Angle), Ellipse_Area); 1154 } 1155#endif 1156 1157 /* If one or both of the scaling vectors is impossibly large 1158 (producing a very large raw F value), we may as well not bother 1159 doing any form of resampling since resampled area is very large. 1160 In this case some alternative means of pixel sampling, such as 1161 the average of the whole image is needed to get a reasonable 1162 result. Calculate only as needed. 1163 */ 1164 if ( (4*A*C - B*B) > MagickMaximumValue ) { 1165 resample_filter->limit_reached = MagickTrue; 1166 return; 1167 } 1168 1169 /* Scale ellipse to match the filters support 1170 (that is, multiply F by the square of the support) 1171 Simplier to just multiply it by the support twice! 1172 */ 1173 F *= resample_filter->support; 1174 F *= resample_filter->support; 1175 1176 /* Orthogonal bounds of the ellipse */ 1177 resample_filter->Ulimit = sqrt(C*F/(A*C-0.25*B*B)); 1178 resample_filter->Vlimit = sqrt(A*F/(A*C-0.25*B*B)); 1179 1180 /* Horizontally aligned parallelogram fitted to Ellipse */ 1181 resample_filter->Uwidth = sqrt(F/A); /* Half of the parallelogram width */ 1182 resample_filter->slope = -B/(2.0*A); /* Reciprocal slope of the parallelogram */ 1183 1184#if DEBUG_ELLIPSE 1185 (void) FormatLocaleFile(stderr, "Ulimit=%lf; Vlimit=%lf; UWidth=%lf; Slope=%lf;\n", 1186 resample_filter->Ulimit, resample_filter->Vlimit, 1187 resample_filter->Uwidth, resample_filter->slope ); 1188#endif 1189 1190 /* Check the absolute area of the parallelogram involved. 1191 * This limit needs more work, as it is too slow for larger images 1192 * with tiled views of the horizon. 1193 */ 1194 if ( (resample_filter->Uwidth * resample_filter->Vlimit) 1195 > (4.0*resample_filter->image_area)) { 1196 resample_filter->limit_reached = MagickTrue; 1197 return; 1198 } 1199 1200 /* Scale ellipse formula to directly index the Filter Lookup Table */ 1201 { register double scale; 1202#if FILTER_LUT 1203 /* scale so that F = WLUT_WIDTH; -- hardcoded */ 1204 scale = (double)WLUT_WIDTH/F; 1205#else 1206 /* scale so that F = resample_filter->F (support^2) */ 1207 scale = resample_filter->F/F; 1208#endif 1209 resample_filter->A = A*scale; 1210 resample_filter->B = B*scale; 1211 resample_filter->C = C*scale; 1212 } 1213} 1214 1215/* 1216%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 1217% % 1218% % 1219% % 1220% S e t R e s a m p l e F i l t e r % 1221% % 1222% % 1223% % 1224%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 1225% 1226% SetResampleFilter() set the resampling filter lookup table based on a 1227% specific filter. Note that the filter is used as a radial filter not as a 1228% two pass othogonally aligned resampling filter. 1229% 1230% The format of the SetResampleFilter method is: 1231% 1232% void SetResampleFilter(ResampleFilter *resample_filter, 1233% const FilterType filter) 1234% 1235% A description of each parameter follows: 1236% 1237% o resample_filter: resampling resample_filterrmation structure 1238% 1239% o filter: the resize filter for elliptical weighting LUT 1240% 1241*/ 1242MagickExport void SetResampleFilter(ResampleFilter *resample_filter, 1243 const FilterType filter) 1244{ 1245 ResizeFilter 1246 *resize_filter; 1247 1248 assert(resample_filter != (ResampleFilter *) NULL); 1249 assert(resample_filter->signature == MagickCoreSignature); 1250 1251 resample_filter->do_interpolate = MagickFalse; 1252 resample_filter->filter = filter; 1253 1254 /* Default cylindrical filter is a Cubic Keys filter */ 1255 if ( filter == UndefinedFilter ) 1256 resample_filter->filter = RobidouxFilter; 1257 1258 if ( resample_filter->filter == PointFilter ) { 1259 resample_filter->do_interpolate = MagickTrue; 1260 return; /* EWA turned off - nothing more to do */ 1261 } 1262 1263 resize_filter = AcquireResizeFilter(resample_filter->image, 1264 resample_filter->filter,MagickTrue,resample_filter->exception); 1265 if (resize_filter == (ResizeFilter *) NULL) { 1266 (void) ThrowMagickException(resample_filter->exception,GetMagickModule(), 1267 ModuleError, "UnableToSetFilteringValue", 1268 "Fall back to Interpolated 'Point' filter"); 1269 resample_filter->filter = PointFilter; 1270 resample_filter->do_interpolate = MagickTrue; 1271 return; /* EWA turned off - nothing more to do */ 1272 } 1273 1274 /* Get the practical working support for the filter, 1275 * after any API call blur factors have been accoded for. 1276 */ 1277#if EWA 1278 resample_filter->support = GetResizeFilterSupport(resize_filter); 1279#else 1280 resample_filter->support = 2.0; /* fixed support size for HQ-EWA */ 1281#endif 1282 1283#if FILTER_LUT 1284 /* Fill the LUT with the weights from the selected filter function */ 1285 { register int 1286 Q; 1287 double 1288 r_scale; 1289 1290 /* Scale radius so the filter LUT covers the full support range */ 1291 r_scale = resample_filter->support*sqrt(1.0/(double)WLUT_WIDTH); 1292 for(Q=0; Q<WLUT_WIDTH; Q++) 1293 resample_filter->filter_lut[Q] = (double) 1294 GetResizeFilterWeight(resize_filter,sqrt((double)Q)*r_scale); 1295 1296 /* finished with the resize filter */ 1297 resize_filter = DestroyResizeFilter(resize_filter); 1298 } 1299#else 1300 /* save the filter and the scaled ellipse bounds needed for filter */ 1301 resample_filter->filter_def = resize_filter; 1302 resample_filter->F = resample_filter->support*resample_filter->support; 1303#endif 1304 1305 /* 1306 Adjust the scaling of the default unit circle 1307 This assumes that any real scaling changes will always 1308 take place AFTER the filter method has been initialized. 1309 */ 1310 ScaleResampleFilter(resample_filter, 1.0, 0.0, 0.0, 1.0); 1311 1312#if 0 1313 /* 1314 This is old code kept as a reference only. Basically it generates 1315 a Gaussian bell curve, with sigma = 0.5 if the support is 2.0 1316 1317 Create Normal Gaussian 2D Filter Weighted Lookup Table. 1318 A normal EWA guassual lookup would use exp(Q*ALPHA) 1319 where Q = distance squared from 0.0 (center) to 1.0 (edge) 1320 and ALPHA = -4.0*ln(2.0) ==> -2.77258872223978123767 1321 The table is of length 1024, and equates to support radius of 2.0 1322 thus needs to be scaled by ALPHA*4/1024 and any blur factor squared 1323 1324 The it comes from reference code provided by Fred Weinhaus. 1325 */ 1326 r_scale = -2.77258872223978123767/(WLUT_WIDTH*blur*blur); 1327 for(Q=0; Q<WLUT_WIDTH; Q++) 1328 resample_filter->filter_lut[Q] = exp((double)Q*r_scale); 1329 resample_filter->support = WLUT_WIDTH; 1330#endif 1331 1332#if FILTER_LUT 1333#if defined(MAGICKCORE_OPENMP_SUPPORT) 1334 #pragma omp single 1335#endif 1336 { 1337 if (IsStringTrue(GetImageArtifact(resample_filter->image, 1338 "resample:verbose")) != MagickFalse) 1339 { 1340 register int 1341 Q; 1342 double 1343 r_scale; 1344 1345 /* Debug output of the filter weighting LUT 1346 Gnuplot the LUT data, the x scale index has been adjusted 1347 plot [0:2][-.2:1] "lut.dat" with lines 1348 The filter values should be normalized for comparision 1349 */ 1350 printf("#\n"); 1351 printf("# Resampling Filter LUT (%d values) for '%s' filter\n", 1352 WLUT_WIDTH, CommandOptionToMnemonic(MagickFilterOptions, 1353 resample_filter->filter) ); 1354 printf("#\n"); 1355 printf("# Note: values in table are using a squared radius lookup.\n"); 1356 printf("# As such its distribution is not uniform.\n"); 1357 printf("#\n"); 1358 printf("# The X value is the support distance for the Y weight\n"); 1359 printf("# so you can use gnuplot to plot this cylindrical filter\n"); 1360 printf("# plot [0:2][-.2:1] \"lut.dat\" with lines\n"); 1361 printf("#\n"); 1362 1363 /* Scale radius so the filter LUT covers the full support range */ 1364 r_scale = resample_filter->support*sqrt(1.0/(double)WLUT_WIDTH); 1365 for(Q=0; Q<WLUT_WIDTH; Q++) 1366 printf("%8.*g %.*g\n", 1367 GetMagickPrecision(),sqrt((double)Q)*r_scale, 1368 GetMagickPrecision(),resample_filter->filter_lut[Q] ); 1369 printf("\n\n"); /* generate a 'break' in gnuplot if multiple outputs */ 1370 } 1371 /* Output the above once only for each image, and each setting 1372 (void) DeleteImageArtifact(resample_filter->image,"resample:verbose"); 1373 */ 1374 } 1375#endif /* FILTER_LUT */ 1376 return; 1377} 1378 1379/* 1380%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 1381% % 1382% % 1383% % 1384% S e t R e s a m p l e F i l t e r I n t e r p o l a t e M e t h o d % 1385% % 1386% % 1387% % 1388%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 1389% 1390% SetResampleFilterInterpolateMethod() sets the resample filter interpolation 1391% method. 1392% 1393% The format of the SetResampleFilterInterpolateMethod method is: 1394% 1395% MagickBooleanType SetResampleFilterInterpolateMethod( 1396% ResampleFilter *resample_filter,const InterpolateMethod method) 1397% 1398% A description of each parameter follows: 1399% 1400% o resample_filter: the resample filter. 1401% 1402% o method: the interpolation method. 1403% 1404*/ 1405MagickExport MagickBooleanType SetResampleFilterInterpolateMethod( 1406 ResampleFilter *resample_filter,const PixelInterpolateMethod method) 1407{ 1408 assert(resample_filter != (ResampleFilter *) NULL); 1409 assert(resample_filter->signature == MagickCoreSignature); 1410 assert(resample_filter->image != (Image *) NULL); 1411 if (resample_filter->debug != MagickFalse) 1412 (void) LogMagickEvent(TraceEvent,GetMagickModule(),"%s", 1413 resample_filter->image->filename); 1414 resample_filter->interpolate=method; 1415 return(MagickTrue); 1416} 1417 1418/* 1419%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 1420% % 1421% % 1422% % 1423% S e t R e s a m p l e F i l t e r V i r t u a l P i x e l M e t h o d % 1424% % 1425% % 1426% % 1427%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 1428% 1429% SetResampleFilterVirtualPixelMethod() changes the virtual pixel method 1430% associated with the specified resample filter. 1431% 1432% The format of the SetResampleFilterVirtualPixelMethod method is: 1433% 1434% MagickBooleanType SetResampleFilterVirtualPixelMethod( 1435% ResampleFilter *resample_filter,const VirtualPixelMethod method) 1436% 1437% A description of each parameter follows: 1438% 1439% o resample_filter: the resample filter. 1440% 1441% o method: the virtual pixel method. 1442% 1443*/ 1444MagickExport MagickBooleanType SetResampleFilterVirtualPixelMethod( 1445 ResampleFilter *resample_filter,const VirtualPixelMethod method) 1446{ 1447 assert(resample_filter != (ResampleFilter *) NULL); 1448 assert(resample_filter->signature == MagickCoreSignature); 1449 assert(resample_filter->image != (Image *) NULL); 1450 if (resample_filter->debug != MagickFalse) 1451 (void) LogMagickEvent(TraceEvent,GetMagickModule(),"%s", 1452 resample_filter->image->filename); 1453 resample_filter->virtual_pixel=method; 1454 if (method != UndefinedVirtualPixelMethod) 1455 (void) SetCacheViewVirtualPixelMethod(resample_filter->view,method); 1456 return(MagickTrue); 1457} 1458