1 /* 2 * jdsample.c 3 * 4 * This file was part of the Independent JPEG Group's software: 5 * Copyright (C) 1991-1996, Thomas G. Lane. 6 * libjpeg-turbo Modifications: 7 * Copyright 2009 Pierre Ossman <ossman (at) cendio.se> for Cendio AB 8 * Copyright (C) 2010, 2015-2016, D. R. Commander. 9 * Copyright (C) 2014, MIPS Technologies, Inc., California. 10 * Copyright (C) 2015, Google, Inc. 11 * For conditions of distribution and use, see the accompanying README.ijg 12 * file. 13 * 14 * This file contains upsampling routines. 15 * 16 * Upsampling input data is counted in "row groups". A row group 17 * is defined to be (v_samp_factor * DCT_scaled_size / min_DCT_scaled_size) 18 * sample rows of each component. Upsampling will normally produce 19 * max_v_samp_factor pixel rows from each row group (but this could vary 20 * if the upsampler is applying a scale factor of its own). 21 * 22 * An excellent reference for image resampling is 23 * Digital Image Warping, George Wolberg, 1990. 24 * Pub. by IEEE Computer Society Press, Los Alamitos, CA. ISBN 0-8186-8944-7. 25 */ 26 27 #include "jinclude.h" 28 #include "jdsample.h" 29 #include "jsimd.h" 30 #include "jpegcomp.h" 31 32 33 34 /* 35 * Initialize for an upsampling pass. 36 */ 37 38 METHODDEF(void) 39 start_pass_upsample (j_decompress_ptr cinfo) 40 { 41 my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample; 42 43 /* Mark the conversion buffer empty */ 44 upsample->next_row_out = cinfo->max_v_samp_factor; 45 /* Initialize total-height counter for detecting bottom of image */ 46 upsample->rows_to_go = cinfo->output_height; 47 } 48 49 50 /* 51 * Control routine to do upsampling (and color conversion). 52 * 53 * In this version we upsample each component independently. 54 * We upsample one row group into the conversion buffer, then apply 55 * color conversion a row at a time. 56 */ 57 58 METHODDEF(void) 59 sep_upsample (j_decompress_ptr cinfo, 60 JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr, 61 JDIMENSION in_row_groups_avail, 62 JSAMPARRAY output_buf, JDIMENSION *out_row_ctr, 63 JDIMENSION out_rows_avail) 64 { 65 my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample; 66 int ci; 67 jpeg_component_info *compptr; 68 JDIMENSION num_rows; 69 70 /* Fill the conversion buffer, if it's empty */ 71 if (upsample->next_row_out >= cinfo->max_v_samp_factor) { 72 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; 73 ci++, compptr++) { 74 /* Invoke per-component upsample method. Notice we pass a POINTER 75 * to color_buf[ci], so that fullsize_upsample can change it. 76 */ 77 (*upsample->methods[ci]) (cinfo, compptr, 78 input_buf[ci] + (*in_row_group_ctr * upsample->rowgroup_height[ci]), 79 upsample->color_buf + ci); 80 } 81 upsample->next_row_out = 0; 82 } 83 84 /* Color-convert and emit rows */ 85 86 /* How many we have in the buffer: */ 87 num_rows = (JDIMENSION) (cinfo->max_v_samp_factor - upsample->next_row_out); 88 /* Not more than the distance to the end of the image. Need this test 89 * in case the image height is not a multiple of max_v_samp_factor: 90 */ 91 if (num_rows > upsample->rows_to_go) 92 num_rows = upsample->rows_to_go; 93 /* And not more than what the client can accept: */ 94 out_rows_avail -= *out_row_ctr; 95 if (num_rows > out_rows_avail) 96 num_rows = out_rows_avail; 97 98 (*cinfo->cconvert->color_convert) (cinfo, upsample->color_buf, 99 (JDIMENSION) upsample->next_row_out, 100 output_buf + *out_row_ctr, 101 (int) num_rows); 102 103 /* Adjust counts */ 104 *out_row_ctr += num_rows; 105 upsample->rows_to_go -= num_rows; 106 upsample->next_row_out += num_rows; 107 /* When the buffer is emptied, declare this input row group consumed */ 108 if (upsample->next_row_out >= cinfo->max_v_samp_factor) 109 (*in_row_group_ctr)++; 110 } 111 112 113 /* 114 * These are the routines invoked by sep_upsample to upsample pixel values 115 * of a single component. One row group is processed per call. 116 */ 117 118 119 /* 120 * For full-size components, we just make color_buf[ci] point at the 121 * input buffer, and thus avoid copying any data. Note that this is 122 * safe only because sep_upsample doesn't declare the input row group 123 * "consumed" until we are done color converting and emitting it. 124 */ 125 126 METHODDEF(void) 127 fullsize_upsample (j_decompress_ptr cinfo, jpeg_component_info *compptr, 128 JSAMPARRAY input_data, JSAMPARRAY *output_data_ptr) 129 { 130 *output_data_ptr = input_data; 131 } 132 133 134 /* 135 * This is a no-op version used for "uninteresting" components. 136 * These components will not be referenced by color conversion. 137 */ 138 139 METHODDEF(void) 140 noop_upsample (j_decompress_ptr cinfo, jpeg_component_info *compptr, 141 JSAMPARRAY input_data, JSAMPARRAY *output_data_ptr) 142 { 143 *output_data_ptr = NULL; /* safety check */ 144 } 145 146 147 /* 148 * This version handles any integral sampling ratios. 149 * This is not used for typical JPEG files, so it need not be fast. 150 * Nor, for that matter, is it particularly accurate: the algorithm is 151 * simple replication of the input pixel onto the corresponding output 152 * pixels. The hi-falutin sampling literature refers to this as a 153 * "box filter". A box filter tends to introduce visible artifacts, 154 * so if you are actually going to use 3:1 or 4:1 sampling ratios 155 * you would be well advised to improve this code. 156 */ 157 158 METHODDEF(void) 159 int_upsample (j_decompress_ptr cinfo, jpeg_component_info *compptr, 160 JSAMPARRAY input_data, JSAMPARRAY *output_data_ptr) 161 { 162 my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample; 163 JSAMPARRAY output_data = *output_data_ptr; 164 register JSAMPROW inptr, outptr; 165 register JSAMPLE invalue; 166 register int h; 167 JSAMPROW outend; 168 int h_expand, v_expand; 169 int inrow, outrow; 170 171 h_expand = upsample->h_expand[compptr->component_index]; 172 v_expand = upsample->v_expand[compptr->component_index]; 173 174 inrow = outrow = 0; 175 while (outrow < cinfo->max_v_samp_factor) { 176 /* Generate one output row with proper horizontal expansion */ 177 inptr = input_data[inrow]; 178 outptr = output_data[outrow]; 179 outend = outptr + cinfo->output_width; 180 while (outptr < outend) { 181 invalue = *inptr++; /* don't need GETJSAMPLE() here */ 182 for (h = h_expand; h > 0; h--) { 183 *outptr++ = invalue; 184 } 185 } 186 /* Generate any additional output rows by duplicating the first one */ 187 if (v_expand > 1) { 188 jcopy_sample_rows(output_data, outrow, output_data, outrow+1, 189 v_expand-1, cinfo->output_width); 190 } 191 inrow++; 192 outrow += v_expand; 193 } 194 } 195 196 197 /* 198 * Fast processing for the common case of 2:1 horizontal and 1:1 vertical. 199 * It's still a box filter. 200 */ 201 202 METHODDEF(void) 203 h2v1_upsample (j_decompress_ptr cinfo, jpeg_component_info *compptr, 204 JSAMPARRAY input_data, JSAMPARRAY *output_data_ptr) 205 { 206 JSAMPARRAY output_data = *output_data_ptr; 207 register JSAMPROW inptr, outptr; 208 register JSAMPLE invalue; 209 JSAMPROW outend; 210 int inrow; 211 212 for (inrow = 0; inrow < cinfo->max_v_samp_factor; inrow++) { 213 inptr = input_data[inrow]; 214 outptr = output_data[inrow]; 215 outend = outptr + cinfo->output_width; 216 while (outptr < outend) { 217 invalue = *inptr++; /* don't need GETJSAMPLE() here */ 218 *outptr++ = invalue; 219 *outptr++ = invalue; 220 } 221 } 222 } 223 224 225 /* 226 * Fast processing for the common case of 2:1 horizontal and 2:1 vertical. 227 * It's still a box filter. 228 */ 229 230 METHODDEF(void) 231 h2v2_upsample (j_decompress_ptr cinfo, jpeg_component_info *compptr, 232 JSAMPARRAY input_data, JSAMPARRAY *output_data_ptr) 233 { 234 JSAMPARRAY output_data = *output_data_ptr; 235 register JSAMPROW inptr, outptr; 236 register JSAMPLE invalue; 237 JSAMPROW outend; 238 int inrow, outrow; 239 240 inrow = outrow = 0; 241 while (outrow < cinfo->max_v_samp_factor) { 242 inptr = input_data[inrow]; 243 outptr = output_data[outrow]; 244 outend = outptr + cinfo->output_width; 245 while (outptr < outend) { 246 invalue = *inptr++; /* don't need GETJSAMPLE() here */ 247 *outptr++ = invalue; 248 *outptr++ = invalue; 249 } 250 jcopy_sample_rows(output_data, outrow, output_data, outrow+1, 251 1, cinfo->output_width); 252 inrow++; 253 outrow += 2; 254 } 255 } 256 257 258 /* 259 * Fancy processing for the common case of 2:1 horizontal and 1:1 vertical. 260 * 261 * The upsampling algorithm is linear interpolation between pixel centers, 262 * also known as a "triangle filter". This is a good compromise between 263 * speed and visual quality. The centers of the output pixels are 1/4 and 3/4 264 * of the way between input pixel centers. 265 * 266 * A note about the "bias" calculations: when rounding fractional values to 267 * integer, we do not want to always round 0.5 up to the next integer. 268 * If we did that, we'd introduce a noticeable bias towards larger values. 269 * Instead, this code is arranged so that 0.5 will be rounded up or down at 270 * alternate pixel locations (a simple ordered dither pattern). 271 */ 272 273 METHODDEF(void) 274 h2v1_fancy_upsample (j_decompress_ptr cinfo, jpeg_component_info *compptr, 275 JSAMPARRAY input_data, JSAMPARRAY *output_data_ptr) 276 { 277 JSAMPARRAY output_data = *output_data_ptr; 278 register JSAMPROW inptr, outptr; 279 register int invalue; 280 register JDIMENSION colctr; 281 int inrow; 282 283 for (inrow = 0; inrow < cinfo->max_v_samp_factor; inrow++) { 284 inptr = input_data[inrow]; 285 outptr = output_data[inrow]; 286 /* Special case for first column */ 287 invalue = GETJSAMPLE(*inptr++); 288 *outptr++ = (JSAMPLE) invalue; 289 *outptr++ = (JSAMPLE) ((invalue * 3 + GETJSAMPLE(*inptr) + 2) >> 2); 290 291 for (colctr = compptr->downsampled_width - 2; colctr > 0; colctr--) { 292 /* General case: 3/4 * nearer pixel + 1/4 * further pixel */ 293 invalue = GETJSAMPLE(*inptr++) * 3; 294 *outptr++ = (JSAMPLE) ((invalue + GETJSAMPLE(inptr[-2]) + 1) >> 2); 295 *outptr++ = (JSAMPLE) ((invalue + GETJSAMPLE(*inptr) + 2) >> 2); 296 } 297 298 /* Special case for last column */ 299 invalue = GETJSAMPLE(*inptr); 300 *outptr++ = (JSAMPLE) ((invalue * 3 + GETJSAMPLE(inptr[-1]) + 1) >> 2); 301 *outptr++ = (JSAMPLE) invalue; 302 } 303 } 304 305 306 /* 307 * Fancy processing for 1:1 horizontal and 2:1 vertical (4:4:0 subsampling). 308 * 309 * This is a less common case, but it can be encountered when losslessly 310 * rotating/transposing a JPEG file that uses 4:2:2 chroma subsampling. 311 */ 312 313 METHODDEF(void) 314 h1v2_fancy_upsample (j_decompress_ptr cinfo, jpeg_component_info *compptr, 315 JSAMPARRAY input_data, JSAMPARRAY *output_data_ptr) 316 { 317 JSAMPARRAY output_data = *output_data_ptr; 318 JSAMPROW inptr0, inptr1, outptr; 319 #if BITS_IN_JSAMPLE == 8 320 int thiscolsum; 321 #else 322 JLONG thiscolsum; 323 #endif 324 JDIMENSION colctr; 325 int inrow, outrow, v; 326 327 inrow = outrow = 0; 328 while (outrow < cinfo->max_v_samp_factor) { 329 for (v = 0; v < 2; v++) { 330 /* inptr0 points to nearest input row, inptr1 points to next nearest */ 331 inptr0 = input_data[inrow]; 332 if (v == 0) /* next nearest is row above */ 333 inptr1 = input_data[inrow-1]; 334 else /* next nearest is row below */ 335 inptr1 = input_data[inrow+1]; 336 outptr = output_data[outrow++]; 337 338 for(colctr = 0; colctr < compptr->downsampled_width; colctr++) { 339 thiscolsum = GETJSAMPLE(*inptr0++) * 3 + GETJSAMPLE(*inptr1++); 340 *outptr++ = (JSAMPLE) ((thiscolsum + 1) >> 2); 341 } 342 } 343 inrow++; 344 } 345 } 346 347 348 /* 349 * Fancy processing for the common case of 2:1 horizontal and 2:1 vertical. 350 * Again a triangle filter; see comments for h2v1 case, above. 351 * 352 * It is OK for us to reference the adjacent input rows because we demanded 353 * context from the main buffer controller (see initialization code). 354 */ 355 356 METHODDEF(void) 357 h2v2_fancy_upsample (j_decompress_ptr cinfo, jpeg_component_info *compptr, 358 JSAMPARRAY input_data, JSAMPARRAY *output_data_ptr) 359 { 360 JSAMPARRAY output_data = *output_data_ptr; 361 register JSAMPROW inptr0, inptr1, outptr; 362 #if BITS_IN_JSAMPLE == 8 363 register int thiscolsum, lastcolsum, nextcolsum; 364 #else 365 register JLONG thiscolsum, lastcolsum, nextcolsum; 366 #endif 367 register JDIMENSION colctr; 368 int inrow, outrow, v; 369 370 inrow = outrow = 0; 371 while (outrow < cinfo->max_v_samp_factor) { 372 for (v = 0; v < 2; v++) { 373 /* inptr0 points to nearest input row, inptr1 points to next nearest */ 374 inptr0 = input_data[inrow]; 375 if (v == 0) /* next nearest is row above */ 376 inptr1 = input_data[inrow-1]; 377 else /* next nearest is row below */ 378 inptr1 = input_data[inrow+1]; 379 outptr = output_data[outrow++]; 380 381 /* Special case for first column */ 382 thiscolsum = GETJSAMPLE(*inptr0++) * 3 + GETJSAMPLE(*inptr1++); 383 nextcolsum = GETJSAMPLE(*inptr0++) * 3 + GETJSAMPLE(*inptr1++); 384 *outptr++ = (JSAMPLE) ((thiscolsum * 4 + 8) >> 4); 385 *outptr++ = (JSAMPLE) ((thiscolsum * 3 + nextcolsum + 7) >> 4); 386 lastcolsum = thiscolsum; thiscolsum = nextcolsum; 387 388 for (colctr = compptr->downsampled_width - 2; colctr > 0; colctr--) { 389 /* General case: 3/4 * nearer pixel + 1/4 * further pixel in each */ 390 /* dimension, thus 9/16, 3/16, 3/16, 1/16 overall */ 391 nextcolsum = GETJSAMPLE(*inptr0++) * 3 + GETJSAMPLE(*inptr1++); 392 *outptr++ = (JSAMPLE) ((thiscolsum * 3 + lastcolsum + 8) >> 4); 393 *outptr++ = (JSAMPLE) ((thiscolsum * 3 + nextcolsum + 7) >> 4); 394 lastcolsum = thiscolsum; thiscolsum = nextcolsum; 395 } 396 397 /* Special case for last column */ 398 *outptr++ = (JSAMPLE) ((thiscolsum * 3 + lastcolsum + 8) >> 4); 399 *outptr++ = (JSAMPLE) ((thiscolsum * 4 + 7) >> 4); 400 } 401 inrow++; 402 } 403 } 404 405 406 /* 407 * Module initialization routine for upsampling. 408 */ 409 410 GLOBAL(void) 411 jinit_upsampler (j_decompress_ptr cinfo) 412 { 413 my_upsample_ptr upsample; 414 int ci; 415 jpeg_component_info *compptr; 416 boolean need_buffer, do_fancy; 417 int h_in_group, v_in_group, h_out_group, v_out_group; 418 419 if (!cinfo->master->jinit_upsampler_no_alloc) { 420 upsample = (my_upsample_ptr) 421 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, 422 sizeof(my_upsampler)); 423 cinfo->upsample = (struct jpeg_upsampler *) upsample; 424 upsample->pub.start_pass = start_pass_upsample; 425 upsample->pub.upsample = sep_upsample; 426 upsample->pub.need_context_rows = FALSE; /* until we find out differently */ 427 } else 428 upsample = (my_upsample_ptr) cinfo->upsample; 429 430 if (cinfo->CCIR601_sampling) /* this isn't supported */ 431 ERREXIT(cinfo, JERR_CCIR601_NOTIMPL); 432 433 /* jdmainct.c doesn't support context rows when min_DCT_scaled_size = 1, 434 * so don't ask for it. 435 */ 436 do_fancy = cinfo->do_fancy_upsampling && cinfo->_min_DCT_scaled_size > 1; 437 438 /* Verify we can handle the sampling factors, select per-component methods, 439 * and create storage as needed. 440 */ 441 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; 442 ci++, compptr++) { 443 /* Compute size of an "input group" after IDCT scaling. This many samples 444 * are to be converted to max_h_samp_factor * max_v_samp_factor pixels. 445 */ 446 h_in_group = (compptr->h_samp_factor * compptr->_DCT_scaled_size) / 447 cinfo->_min_DCT_scaled_size; 448 v_in_group = (compptr->v_samp_factor * compptr->_DCT_scaled_size) / 449 cinfo->_min_DCT_scaled_size; 450 h_out_group = cinfo->max_h_samp_factor; 451 v_out_group = cinfo->max_v_samp_factor; 452 upsample->rowgroup_height[ci] = v_in_group; /* save for use later */ 453 need_buffer = TRUE; 454 if (! compptr->component_needed) { 455 /* Don't bother to upsample an uninteresting component. */ 456 upsample->methods[ci] = noop_upsample; 457 need_buffer = FALSE; 458 } else if (h_in_group == h_out_group && v_in_group == v_out_group) { 459 /* Fullsize components can be processed without any work. */ 460 upsample->methods[ci] = fullsize_upsample; 461 need_buffer = FALSE; 462 } else if (h_in_group * 2 == h_out_group && 463 v_in_group == v_out_group) { 464 /* Special cases for 2h1v upsampling */ 465 if (do_fancy && compptr->downsampled_width > 2) { 466 if (jsimd_can_h2v1_fancy_upsample()) 467 upsample->methods[ci] = jsimd_h2v1_fancy_upsample; 468 else 469 upsample->methods[ci] = h2v1_fancy_upsample; 470 } else { 471 if (jsimd_can_h2v1_upsample()) 472 upsample->methods[ci] = jsimd_h2v1_upsample; 473 else 474 upsample->methods[ci] = h2v1_upsample; 475 } 476 } else if (h_in_group == h_out_group && 477 v_in_group * 2 == v_out_group && do_fancy) { 478 /* Non-fancy upsampling is handled by the generic method */ 479 upsample->methods[ci] = h1v2_fancy_upsample; 480 upsample->pub.need_context_rows = TRUE; 481 } else if (h_in_group * 2 == h_out_group && 482 v_in_group * 2 == v_out_group) { 483 /* Special cases for 2h2v upsampling */ 484 if (do_fancy && compptr->downsampled_width > 2) { 485 if (jsimd_can_h2v2_fancy_upsample()) 486 upsample->methods[ci] = jsimd_h2v2_fancy_upsample; 487 else 488 upsample->methods[ci] = h2v2_fancy_upsample; 489 upsample->pub.need_context_rows = TRUE; 490 } else { 491 if (jsimd_can_h2v2_upsample()) 492 upsample->methods[ci] = jsimd_h2v2_upsample; 493 else 494 upsample->methods[ci] = h2v2_upsample; 495 } 496 } else if ((h_out_group % h_in_group) == 0 && 497 (v_out_group % v_in_group) == 0) { 498 /* Generic integral-factors upsampling method */ 499 #if defined(__mips__) 500 if (jsimd_can_int_upsample()) 501 upsample->methods[ci] = jsimd_int_upsample; 502 else 503 #endif 504 upsample->methods[ci] = int_upsample; 505 upsample->h_expand[ci] = (UINT8) (h_out_group / h_in_group); 506 upsample->v_expand[ci] = (UINT8) (v_out_group / v_in_group); 507 } else 508 ERREXIT(cinfo, JERR_FRACT_SAMPLE_NOTIMPL); 509 if (need_buffer && !cinfo->master->jinit_upsampler_no_alloc) { 510 upsample->color_buf[ci] = (*cinfo->mem->alloc_sarray) 511 ((j_common_ptr) cinfo, JPOOL_IMAGE, 512 (JDIMENSION) jround_up((long) cinfo->output_width, 513 (long) cinfo->max_h_samp_factor), 514 (JDIMENSION) cinfo->max_v_samp_factor); 515 } 516 } 517 } 518
