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, D. R. Commander. 9 * For conditions of distribution and use, see the accompanying README file. 10 * 11 * This file contains upsampling routines. 12 * 13 * Upsampling input data is counted in "row groups". A row group 14 * is defined to be (v_samp_factor * DCT_scaled_size / min_DCT_scaled_size) 15 * sample rows of each component. Upsampling will normally produce 16 * max_v_samp_factor pixel rows from each row group (but this could vary 17 * if the upsampler is applying a scale factor of its own). 18 * 19 * An excellent reference for image resampling is 20 * Digital Image Warping, George Wolberg, 1990. 21 * Pub. by IEEE Computer Society Press, Los Alamitos, CA. ISBN 0-8186-8944-7. 22 */ 23 24 #define JPEG_INTERNALS 25 #include "jinclude.h" 26 #include "jpeglib.h" 27 #include "jsimd.h" 28 #include "jpegcomp.h" 29 30 31 /* Pointer to routine to upsample a single component */ 32 typedef JMETHOD(void, upsample1_ptr, 33 (j_decompress_ptr cinfo, jpeg_component_info * compptr, 34 JSAMPARRAY input_data, JSAMPARRAY * output_data_ptr)); 35 36 /* Private subobject */ 37 38 typedef struct { 39 struct jpeg_upsampler pub; /* public fields */ 40 41 /* Color conversion buffer. When using separate upsampling and color 42 * conversion steps, this buffer holds one upsampled row group until it 43 * has been color converted and output. 44 * Note: we do not allocate any storage for component(s) which are full-size, 45 * ie do not need rescaling. The corresponding entry of color_buf[] is 46 * simply set to point to the input data array, thereby avoiding copying. 47 */ 48 JSAMPARRAY color_buf[MAX_COMPONENTS]; 49 50 /* Per-component upsampling method pointers */ 51 upsample1_ptr methods[MAX_COMPONENTS]; 52 53 int next_row_out; /* counts rows emitted from color_buf */ 54 JDIMENSION rows_to_go; /* counts rows remaining in image */ 55 56 /* Height of an input row group for each component. */ 57 int rowgroup_height[MAX_COMPONENTS]; 58 59 /* These arrays save pixel expansion factors so that int_expand need not 60 * recompute them each time. They are unused for other upsampling methods. 61 */ 62 UINT8 h_expand[MAX_COMPONENTS]; 63 UINT8 v_expand[MAX_COMPONENTS]; 64 } my_upsampler; 65 66 typedef my_upsampler * my_upsample_ptr; 67 68 69 /* 70 * Initialize for an upsampling pass. 71 */ 72 73 METHODDEF(void) 74 start_pass_upsample (j_decompress_ptr cinfo) 75 { 76 my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample; 77 78 /* Mark the conversion buffer empty */ 79 upsample->next_row_out = cinfo->max_v_samp_factor; 80 /* Initialize total-height counter for detecting bottom of image */ 81 upsample->rows_to_go = cinfo->output_height; 82 } 83 84 85 /* 86 * Control routine to do upsampling (and color conversion). 87 * 88 * In this version we upsample each component independently. 89 * We upsample one row group into the conversion buffer, then apply 90 * color conversion a row at a time. 91 */ 92 93 METHODDEF(void) 94 sep_upsample (j_decompress_ptr cinfo, 95 JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr, 96 JDIMENSION in_row_groups_avail, 97 JSAMPARRAY output_buf, JDIMENSION *out_row_ctr, 98 JDIMENSION out_rows_avail) 99 { 100 my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample; 101 int ci; 102 jpeg_component_info * compptr; 103 JDIMENSION num_rows; 104 105 /* Fill the conversion buffer, if it's empty */ 106 if (upsample->next_row_out >= cinfo->max_v_samp_factor) { 107 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; 108 ci++, compptr++) { 109 /* Invoke per-component upsample method. Notice we pass a POINTER 110 * to color_buf[ci], so that fullsize_upsample can change it. 111 */ 112 (*upsample->methods[ci]) (cinfo, compptr, 113 input_buf[ci] + (*in_row_group_ctr * upsample->rowgroup_height[ci]), 114 upsample->color_buf + ci); 115 } 116 upsample->next_row_out = 0; 117 } 118 119 /* Color-convert and emit rows */ 120 121 /* How many we have in the buffer: */ 122 num_rows = (JDIMENSION) (cinfo->max_v_samp_factor - upsample->next_row_out); 123 /* Not more than the distance to the end of the image. Need this test 124 * in case the image height is not a multiple of max_v_samp_factor: 125 */ 126 if (num_rows > upsample->rows_to_go) 127 num_rows = upsample->rows_to_go; 128 /* And not more than what the client can accept: */ 129 out_rows_avail -= *out_row_ctr; 130 if (num_rows > out_rows_avail) 131 num_rows = out_rows_avail; 132 133 (*cinfo->cconvert->color_convert) (cinfo, upsample->color_buf, 134 (JDIMENSION) upsample->next_row_out, 135 output_buf + *out_row_ctr, 136 (int) num_rows); 137 138 /* Adjust counts */ 139 *out_row_ctr += num_rows; 140 upsample->rows_to_go -= num_rows; 141 upsample->next_row_out += num_rows; 142 /* When the buffer is emptied, declare this input row group consumed */ 143 if (upsample->next_row_out >= cinfo->max_v_samp_factor) 144 (*in_row_group_ctr)++; 145 } 146 147 148 /* 149 * These are the routines invoked by sep_upsample to upsample pixel values 150 * of a single component. One row group is processed per call. 151 */ 152 153 154 /* 155 * For full-size components, we just make color_buf[ci] point at the 156 * input buffer, and thus avoid copying any data. Note that this is 157 * safe only because sep_upsample doesn't declare the input row group 158 * "consumed" until we are done color converting and emitting it. 159 */ 160 161 METHODDEF(void) 162 fullsize_upsample (j_decompress_ptr cinfo, jpeg_component_info * compptr, 163 JSAMPARRAY input_data, JSAMPARRAY * output_data_ptr) 164 { 165 *output_data_ptr = input_data; 166 } 167 168 169 /* 170 * This is a no-op version used for "uninteresting" components. 171 * These components will not be referenced by color conversion. 172 */ 173 174 METHODDEF(void) 175 noop_upsample (j_decompress_ptr cinfo, jpeg_component_info * compptr, 176 JSAMPARRAY input_data, JSAMPARRAY * output_data_ptr) 177 { 178 *output_data_ptr = NULL; /* safety check */ 179 } 180 181 182 /* 183 * This version handles any integral sampling ratios. 184 * This is not used for typical JPEG files, so it need not be fast. 185 * Nor, for that matter, is it particularly accurate: the algorithm is 186 * simple replication of the input pixel onto the corresponding output 187 * pixels. The hi-falutin sampling literature refers to this as a 188 * "box filter". A box filter tends to introduce visible artifacts, 189 * so if you are actually going to use 3:1 or 4:1 sampling ratios 190 * you would be well advised to improve this code. 191 */ 192 193 METHODDEF(void) 194 int_upsample (j_decompress_ptr cinfo, jpeg_component_info * compptr, 195 JSAMPARRAY input_data, JSAMPARRAY * output_data_ptr) 196 { 197 my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample; 198 JSAMPARRAY output_data = *output_data_ptr; 199 register JSAMPROW inptr, outptr; 200 register JSAMPLE invalue; 201 register int h; 202 JSAMPROW outend; 203 int h_expand, v_expand; 204 int inrow, outrow; 205 206 h_expand = upsample->h_expand[compptr->component_index]; 207 v_expand = upsample->v_expand[compptr->component_index]; 208 209 inrow = outrow = 0; 210 while (outrow < cinfo->max_v_samp_factor) { 211 /* Generate one output row with proper horizontal expansion */ 212 inptr = input_data[inrow]; 213 outptr = output_data[outrow]; 214 outend = outptr + cinfo->output_width; 215 while (outptr < outend) { 216 invalue = *inptr++; /* don't need GETJSAMPLE() here */ 217 for (h = h_expand; h > 0; h--) { 218 *outptr++ = invalue; 219 } 220 } 221 /* Generate any additional output rows by duplicating the first one */ 222 if (v_expand > 1) { 223 jcopy_sample_rows(output_data, outrow, output_data, outrow+1, 224 v_expand-1, cinfo->output_width); 225 } 226 inrow++; 227 outrow += v_expand; 228 } 229 } 230 231 232 /* 233 * Fast processing for the common case of 2:1 horizontal and 1:1 vertical. 234 * It's still a box filter. 235 */ 236 237 METHODDEF(void) 238 h2v1_upsample (j_decompress_ptr cinfo, jpeg_component_info * compptr, 239 JSAMPARRAY input_data, JSAMPARRAY * output_data_ptr) 240 { 241 JSAMPARRAY output_data = *output_data_ptr; 242 register JSAMPROW inptr, outptr; 243 register JSAMPLE invalue; 244 JSAMPROW outend; 245 int inrow; 246 247 for (inrow = 0; inrow < cinfo->max_v_samp_factor; inrow++) { 248 inptr = input_data[inrow]; 249 outptr = output_data[inrow]; 250 outend = outptr + cinfo->output_width; 251 while (outptr < outend) { 252 invalue = *inptr++; /* don't need GETJSAMPLE() here */ 253 *outptr++ = invalue; 254 *outptr++ = invalue; 255 } 256 } 257 } 258 259 260 /* 261 * Fast processing for the common case of 2:1 horizontal and 2:1 vertical. 262 * It's still a box filter. 263 */ 264 265 METHODDEF(void) 266 h2v2_upsample (j_decompress_ptr cinfo, jpeg_component_info * compptr, 267 JSAMPARRAY input_data, JSAMPARRAY * output_data_ptr) 268 { 269 JSAMPARRAY output_data = *output_data_ptr; 270 register JSAMPROW inptr, outptr; 271 register JSAMPLE invalue; 272 JSAMPROW outend; 273 int inrow, outrow; 274 275 inrow = outrow = 0; 276 while (outrow < cinfo->max_v_samp_factor) { 277 inptr = input_data[inrow]; 278 outptr = output_data[outrow]; 279 outend = outptr + cinfo->output_width; 280 while (outptr < outend) { 281 invalue = *inptr++; /* don't need GETJSAMPLE() here */ 282 *outptr++ = invalue; 283 *outptr++ = invalue; 284 } 285 jcopy_sample_rows(output_data, outrow, output_data, outrow+1, 286 1, cinfo->output_width); 287 inrow++; 288 outrow += 2; 289 } 290 } 291 292 293 /* 294 * Fancy processing for the common case of 2:1 horizontal and 1:1 vertical. 295 * 296 * The upsampling algorithm is linear interpolation between pixel centers, 297 * also known as a "triangle filter". This is a good compromise between 298 * speed and visual quality. The centers of the output pixels are 1/4 and 3/4 299 * of the way between input pixel centers. 300 * 301 * A note about the "bias" calculations: when rounding fractional values to 302 * integer, we do not want to always round 0.5 up to the next integer. 303 * If we did that, we'd introduce a noticeable bias towards larger values. 304 * Instead, this code is arranged so that 0.5 will be rounded up or down at 305 * alternate pixel locations (a simple ordered dither pattern). 306 */ 307 308 METHODDEF(void) 309 h2v1_fancy_upsample (j_decompress_ptr cinfo, jpeg_component_info * compptr, 310 JSAMPARRAY input_data, JSAMPARRAY * output_data_ptr) 311 { 312 JSAMPARRAY output_data = *output_data_ptr; 313 register JSAMPROW inptr, outptr; 314 register int invalue; 315 register JDIMENSION colctr; 316 int inrow; 317 318 for (inrow = 0; inrow < cinfo->max_v_samp_factor; inrow++) { 319 inptr = input_data[inrow]; 320 outptr = output_data[inrow]; 321 /* Special case for first column */ 322 invalue = GETJSAMPLE(*inptr++); 323 *outptr++ = (JSAMPLE) invalue; 324 *outptr++ = (JSAMPLE) ((invalue * 3 + GETJSAMPLE(*inptr) + 2) >> 2); 325 326 for (colctr = compptr->downsampled_width - 2; colctr > 0; colctr--) { 327 /* General case: 3/4 * nearer pixel + 1/4 * further pixel */ 328 invalue = GETJSAMPLE(*inptr++) * 3; 329 *outptr++ = (JSAMPLE) ((invalue + GETJSAMPLE(inptr[-2]) + 1) >> 2); 330 *outptr++ = (JSAMPLE) ((invalue + GETJSAMPLE(*inptr) + 2) >> 2); 331 } 332 333 /* Special case for last column */ 334 invalue = GETJSAMPLE(*inptr); 335 *outptr++ = (JSAMPLE) ((invalue * 3 + GETJSAMPLE(inptr[-1]) + 1) >> 2); 336 *outptr++ = (JSAMPLE) invalue; 337 } 338 } 339 340 341 /* 342 * Fancy processing for the common case of 2:1 horizontal and 2:1 vertical. 343 * Again a triangle filter; see comments for h2v1 case, above. 344 * 345 * It is OK for us to reference the adjacent input rows because we demanded 346 * context from the main buffer controller (see initialization code). 347 */ 348 349 METHODDEF(void) 350 h2v2_fancy_upsample (j_decompress_ptr cinfo, jpeg_component_info * compptr, 351 JSAMPARRAY input_data, JSAMPARRAY * output_data_ptr) 352 { 353 JSAMPARRAY output_data = *output_data_ptr; 354 register JSAMPROW inptr0, inptr1, outptr; 355 #if BITS_IN_JSAMPLE == 8 356 register int thiscolsum, lastcolsum, nextcolsum; 357 #else 358 register INT32 thiscolsum, lastcolsum, nextcolsum; 359 #endif 360 register JDIMENSION colctr; 361 int inrow, outrow, v; 362 363 inrow = outrow = 0; 364 while (outrow < cinfo->max_v_samp_factor) { 365 for (v = 0; v < 2; v++) { 366 /* inptr0 points to nearest input row, inptr1 points to next nearest */ 367 inptr0 = input_data[inrow]; 368 if (v == 0) /* next nearest is row above */ 369 inptr1 = input_data[inrow-1]; 370 else /* next nearest is row below */ 371 inptr1 = input_data[inrow+1]; 372 outptr = output_data[outrow++]; 373 374 /* Special case for first column */ 375 thiscolsum = GETJSAMPLE(*inptr0++) * 3 + GETJSAMPLE(*inptr1++); 376 nextcolsum = GETJSAMPLE(*inptr0++) * 3 + GETJSAMPLE(*inptr1++); 377 *outptr++ = (JSAMPLE) ((thiscolsum * 4 + 8) >> 4); 378 *outptr++ = (JSAMPLE) ((thiscolsum * 3 + nextcolsum + 7) >> 4); 379 lastcolsum = thiscolsum; thiscolsum = nextcolsum; 380 381 for (colctr = compptr->downsampled_width - 2; colctr > 0; colctr--) { 382 /* General case: 3/4 * nearer pixel + 1/4 * further pixel in each */ 383 /* dimension, thus 9/16, 3/16, 3/16, 1/16 overall */ 384 nextcolsum = GETJSAMPLE(*inptr0++) * 3 + GETJSAMPLE(*inptr1++); 385 *outptr++ = (JSAMPLE) ((thiscolsum * 3 + lastcolsum + 8) >> 4); 386 *outptr++ = (JSAMPLE) ((thiscolsum * 3 + nextcolsum + 7) >> 4); 387 lastcolsum = thiscolsum; thiscolsum = nextcolsum; 388 } 389 390 /* Special case for last column */ 391 *outptr++ = (JSAMPLE) ((thiscolsum * 3 + lastcolsum + 8) >> 4); 392 *outptr++ = (JSAMPLE) ((thiscolsum * 4 + 7) >> 4); 393 } 394 inrow++; 395 } 396 } 397 398 399 /* 400 * Module initialization routine for upsampling. 401 */ 402 403 GLOBAL(void) 404 jinit_upsampler (j_decompress_ptr cinfo) 405 { 406 my_upsample_ptr upsample; 407 int ci; 408 jpeg_component_info * compptr; 409 boolean need_buffer, do_fancy; 410 int h_in_group, v_in_group, h_out_group, v_out_group; 411 412 upsample = (my_upsample_ptr) 413 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, 414 SIZEOF(my_upsampler)); 415 cinfo->upsample = (struct jpeg_upsampler *) upsample; 416 upsample->pub.start_pass = start_pass_upsample; 417 upsample->pub.upsample = sep_upsample; 418 upsample->pub.need_context_rows = FALSE; /* until we find out differently */ 419 420 if (cinfo->CCIR601_sampling) /* this isn't supported */ 421 ERREXIT(cinfo, JERR_CCIR601_NOTIMPL); 422 423 /* jdmainct.c doesn't support context rows when min_DCT_scaled_size = 1, 424 * so don't ask for it. 425 */ 426 do_fancy = cinfo->do_fancy_upsampling && cinfo->_min_DCT_scaled_size > 1; 427 428 /* Verify we can handle the sampling factors, select per-component methods, 429 * and create storage as needed. 430 */ 431 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; 432 ci++, compptr++) { 433 /* Compute size of an "input group" after IDCT scaling. This many samples 434 * are to be converted to max_h_samp_factor * max_v_samp_factor pixels. 435 */ 436 h_in_group = (compptr->h_samp_factor * compptr->_DCT_scaled_size) / 437 cinfo->_min_DCT_scaled_size; 438 v_in_group = (compptr->v_samp_factor * compptr->_DCT_scaled_size) / 439 cinfo->_min_DCT_scaled_size; 440 h_out_group = cinfo->max_h_samp_factor; 441 v_out_group = cinfo->max_v_samp_factor; 442 upsample->rowgroup_height[ci] = v_in_group; /* save for use later */ 443 need_buffer = TRUE; 444 if (! compptr->component_needed) { 445 /* Don't bother to upsample an uninteresting component. */ 446 upsample->methods[ci] = noop_upsample; 447 need_buffer = FALSE; 448 } else if (h_in_group == h_out_group && v_in_group == v_out_group) { 449 /* Fullsize components can be processed without any work. */ 450 upsample->methods[ci] = fullsize_upsample; 451 need_buffer = FALSE; 452 } else if (h_in_group * 2 == h_out_group && 453 v_in_group == v_out_group) { 454 /* Special cases for 2h1v upsampling */ 455 if (do_fancy && compptr->downsampled_width > 2) { 456 if (jsimd_can_h2v1_fancy_upsample()) 457 upsample->methods[ci] = jsimd_h2v1_fancy_upsample; 458 else 459 upsample->methods[ci] = h2v1_fancy_upsample; 460 } else { 461 if (jsimd_can_h2v1_upsample()) 462 upsample->methods[ci] = jsimd_h2v1_upsample; 463 else 464 upsample->methods[ci] = h2v1_upsample; 465 } 466 } else if (h_in_group * 2 == h_out_group && 467 v_in_group * 2 == v_out_group) { 468 /* Special cases for 2h2v upsampling */ 469 if (do_fancy && compptr->downsampled_width > 2) { 470 if (jsimd_can_h2v2_fancy_upsample()) 471 upsample->methods[ci] = jsimd_h2v2_fancy_upsample; 472 else 473 upsample->methods[ci] = h2v2_fancy_upsample; 474 upsample->pub.need_context_rows = TRUE; 475 } else { 476 if (jsimd_can_h2v2_upsample()) 477 upsample->methods[ci] = jsimd_h2v2_upsample; 478 else 479 upsample->methods[ci] = h2v2_upsample; 480 } 481 } else if ((h_out_group % h_in_group) == 0 && 482 (v_out_group % v_in_group) == 0) { 483 /* Generic integral-factors upsampling method */ 484 upsample->methods[ci] = int_upsample; 485 upsample->h_expand[ci] = (UINT8) (h_out_group / h_in_group); 486 upsample->v_expand[ci] = (UINT8) (v_out_group / v_in_group); 487 } else 488 ERREXIT(cinfo, JERR_FRACT_SAMPLE_NOTIMPL); 489 if (need_buffer) { 490 upsample->color_buf[ci] = (*cinfo->mem->alloc_sarray) 491 ((j_common_ptr) cinfo, JPOOL_IMAGE, 492 (JDIMENSION) jround_up((long) cinfo->output_width, 493 (long) cinfo->max_h_samp_factor), 494 (JDIMENSION) cinfo->max_v_samp_factor); 495 } 496 } 497 } 498
