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 * 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 "jdsample.h" 28 #include "jsimd.h" 29 #include "jpegcomp.h" 30 31 32 33 /* 34 * Initialize for an upsampling pass. 35 */ 36 37 METHODDEF(void) 38 start_pass_upsample (j_decompress_ptr cinfo) 39 { 40 my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample; 41 42 /* Mark the conversion buffer empty */ 43 upsample->next_row_out = cinfo->max_v_samp_factor; 44 /* Initialize total-height counter for detecting bottom of image */ 45 upsample->rows_to_go = cinfo->output_height; 46 } 47 48 49 /* 50 * Control routine to do upsampling (and color conversion). 51 * 52 * In this version we upsample each component independently. 53 * We upsample one row group into the conversion buffer, then apply 54 * color conversion a row at a time. 55 */ 56 57 METHODDEF(void) 58 sep_upsample (j_decompress_ptr cinfo, 59 JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr, 60 JDIMENSION in_row_groups_avail, 61 JSAMPARRAY output_buf, JDIMENSION *out_row_ctr, 62 JDIMENSION out_rows_avail) 63 { 64 my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample; 65 int ci; 66 jpeg_component_info * compptr; 67 JDIMENSION num_rows; 68 69 /* Fill the conversion buffer, if it's empty */ 70 if (upsample->next_row_out >= cinfo->max_v_samp_factor) { 71 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; 72 ci++, compptr++) { 73 /* Invoke per-component upsample method. Notice we pass a POINTER 74 * to color_buf[ci], so that fullsize_upsample can change it. 75 */ 76 (*upsample->methods[ci]) (cinfo, compptr, 77 input_buf[ci] + (*in_row_group_ctr * upsample->rowgroup_height[ci]), 78 upsample->color_buf + ci); 79 } 80 upsample->next_row_out = 0; 81 } 82 83 /* Color-convert and emit rows */ 84 85 /* How many we have in the buffer: */ 86 num_rows = (JDIMENSION) (cinfo->max_v_samp_factor - upsample->next_row_out); 87 /* Not more than the distance to the end of the image. Need this test 88 * in case the image height is not a multiple of max_v_samp_factor: 89 */ 90 if (num_rows > upsample->rows_to_go) 91 num_rows = upsample->rows_to_go; 92 /* And not more than what the client can accept: */ 93 out_rows_avail -= *out_row_ctr; 94 if (num_rows > out_rows_avail) 95 num_rows = out_rows_avail; 96 97 (*cinfo->cconvert->color_convert) (cinfo, upsample->color_buf, 98 (JDIMENSION) upsample->next_row_out, 99 output_buf + *out_row_ctr, 100 (int) num_rows); 101 102 /* Adjust counts */ 103 *out_row_ctr += num_rows; 104 upsample->rows_to_go -= num_rows; 105 upsample->next_row_out += num_rows; 106 /* When the buffer is emptied, declare this input row group consumed */ 107 if (upsample->next_row_out >= cinfo->max_v_samp_factor) 108 (*in_row_group_ctr)++; 109 } 110 111 112 /* 113 * These are the routines invoked by sep_upsample to upsample pixel values 114 * of a single component. One row group is processed per call. 115 */ 116 117 118 /* 119 * For full-size components, we just make color_buf[ci] point at the 120 * input buffer, and thus avoid copying any data. Note that this is 121 * safe only because sep_upsample doesn't declare the input row group 122 * "consumed" until we are done color converting and emitting it. 123 */ 124 125 METHODDEF(void) 126 fullsize_upsample (j_decompress_ptr cinfo, jpeg_component_info * compptr, 127 JSAMPARRAY input_data, JSAMPARRAY * output_data_ptr) 128 { 129 *output_data_ptr = input_data; 130 } 131 132 133 /* 134 * This is a no-op version used for "uninteresting" components. 135 * These components will not be referenced by color conversion. 136 */ 137 138 METHODDEF(void) 139 noop_upsample (j_decompress_ptr cinfo, jpeg_component_info * compptr, 140 JSAMPARRAY input_data, JSAMPARRAY * output_data_ptr) 141 { 142 *output_data_ptr = NULL; /* safety check */ 143 } 144 145 146 /* 147 * This version handles any integral sampling ratios. 148 * This is not used for typical JPEG files, so it need not be fast. 149 * Nor, for that matter, is it particularly accurate: the algorithm is 150 * simple replication of the input pixel onto the corresponding output 151 * pixels. The hi-falutin sampling literature refers to this as a 152 * "box filter". A box filter tends to introduce visible artifacts, 153 * so if you are actually going to use 3:1 or 4:1 sampling ratios 154 * you would be well advised to improve this code. 155 */ 156 157 METHODDEF(void) 158 int_upsample (j_decompress_ptr cinfo, jpeg_component_info * compptr, 159 JSAMPARRAY input_data, JSAMPARRAY * output_data_ptr) 160 { 161 my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample; 162 JSAMPARRAY output_data = *output_data_ptr; 163 register JSAMPROW inptr, outptr; 164 register JSAMPLE invalue; 165 register int h; 166 JSAMPROW outend; 167 int h_expand, v_expand; 168 int inrow, outrow; 169 170 h_expand = upsample->h_expand[compptr->component_index]; 171 v_expand = upsample->v_expand[compptr->component_index]; 172 173 inrow = outrow = 0; 174 while (outrow < cinfo->max_v_samp_factor) { 175 /* Generate one output row with proper horizontal expansion */ 176 inptr = input_data[inrow]; 177 outptr = output_data[outrow]; 178 outend = outptr + cinfo->output_width; 179 while (outptr < outend) { 180 invalue = *inptr++; /* don't need GETJSAMPLE() here */ 181 for (h = h_expand; h > 0; h--) { 182 *outptr++ = invalue; 183 } 184 } 185 /* Generate any additional output rows by duplicating the first one */ 186 if (v_expand > 1) { 187 jcopy_sample_rows(output_data, outrow, output_data, outrow+1, 188 v_expand-1, cinfo->output_width); 189 } 190 inrow++; 191 outrow += v_expand; 192 } 193 } 194 195 196 /* 197 * Fast processing for the common case of 2:1 horizontal and 1:1 vertical. 198 * It's still a box filter. 199 */ 200 201 METHODDEF(void) 202 h2v1_upsample (j_decompress_ptr cinfo, jpeg_component_info * compptr, 203 JSAMPARRAY input_data, JSAMPARRAY * output_data_ptr) 204 { 205 JSAMPARRAY output_data = *output_data_ptr; 206 register JSAMPROW inptr, outptr; 207 register JSAMPLE invalue; 208 JSAMPROW outend; 209 int inrow; 210 211 for (inrow = 0; inrow < cinfo->max_v_samp_factor; inrow++) { 212 inptr = input_data[inrow]; 213 outptr = output_data[inrow]; 214 outend = outptr + cinfo->output_width; 215 while (outptr < outend) { 216 invalue = *inptr++; /* don't need GETJSAMPLE() here */ 217 *outptr++ = invalue; 218 *outptr++ = invalue; 219 } 220 } 221 } 222 223 224 /* 225 * Fast processing for the common case of 2:1 horizontal and 2:1 vertical. 226 * It's still a box filter. 227 */ 228 229 METHODDEF(void) 230 h2v2_upsample (j_decompress_ptr cinfo, jpeg_component_info * compptr, 231 JSAMPARRAY input_data, JSAMPARRAY * output_data_ptr) 232 { 233 JSAMPARRAY output_data = *output_data_ptr; 234 register JSAMPROW inptr, outptr; 235 register JSAMPLE invalue; 236 JSAMPROW outend; 237 int inrow, outrow; 238 239 inrow = outrow = 0; 240 while (outrow < cinfo->max_v_samp_factor) { 241 inptr = input_data[inrow]; 242 outptr = output_data[outrow]; 243 outend = outptr + cinfo->output_width; 244 while (outptr < outend) { 245 invalue = *inptr++; /* don't need GETJSAMPLE() here */ 246 *outptr++ = invalue; 247 *outptr++ = invalue; 248 } 249 jcopy_sample_rows(output_data, outrow, output_data, outrow+1, 250 1, cinfo->output_width); 251 inrow++; 252 outrow += 2; 253 } 254 } 255 256 257 /* 258 * Fancy processing for the common case of 2:1 horizontal and 1:1 vertical. 259 * 260 * The upsampling algorithm is linear interpolation between pixel centers, 261 * also known as a "triangle filter". This is a good compromise between 262 * speed and visual quality. The centers of the output pixels are 1/4 and 3/4 263 * of the way between input pixel centers. 264 * 265 * A note about the "bias" calculations: when rounding fractional values to 266 * integer, we do not want to always round 0.5 up to the next integer. 267 * If we did that, we'd introduce a noticeable bias towards larger values. 268 * Instead, this code is arranged so that 0.5 will be rounded up or down at 269 * alternate pixel locations (a simple ordered dither pattern). 270 */ 271 272 METHODDEF(void) 273 h2v1_fancy_upsample (j_decompress_ptr cinfo, jpeg_component_info * compptr, 274 JSAMPARRAY input_data, JSAMPARRAY * output_data_ptr) 275 { 276 JSAMPARRAY output_data = *output_data_ptr; 277 register JSAMPROW inptr, outptr; 278 register int invalue; 279 register JDIMENSION colctr; 280 int inrow; 281 282 for (inrow = 0; inrow < cinfo->max_v_samp_factor; inrow++) { 283 inptr = input_data[inrow]; 284 outptr = output_data[inrow]; 285 /* Special case for first column */ 286 invalue = GETJSAMPLE(*inptr++); 287 *outptr++ = (JSAMPLE) invalue; 288 *outptr++ = (JSAMPLE) ((invalue * 3 + GETJSAMPLE(*inptr) + 2) >> 2); 289 290 for (colctr = compptr->downsampled_width - 2; colctr > 0; colctr--) { 291 /* General case: 3/4 * nearer pixel + 1/4 * further pixel */ 292 invalue = GETJSAMPLE(*inptr++) * 3; 293 *outptr++ = (JSAMPLE) ((invalue + GETJSAMPLE(inptr[-2]) + 1) >> 2); 294 *outptr++ = (JSAMPLE) ((invalue + GETJSAMPLE(*inptr) + 2) >> 2); 295 } 296 297 /* Special case for last column */ 298 invalue = GETJSAMPLE(*inptr); 299 *outptr++ = (JSAMPLE) ((invalue * 3 + GETJSAMPLE(inptr[-1]) + 1) >> 2); 300 *outptr++ = (JSAMPLE) invalue; 301 } 302 } 303 304 305 /* 306 * Fancy processing for the common case of 2:1 horizontal and 2:1 vertical. 307 * Again a triangle filter; see comments for h2v1 case, above. 308 * 309 * It is OK for us to reference the adjacent input rows because we demanded 310 * context from the main buffer controller (see initialization code). 311 */ 312 313 METHODDEF(void) 314 h2v2_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 register JSAMPROW inptr0, inptr1, outptr; 319 #if BITS_IN_JSAMPLE == 8 320 register int thiscolsum, lastcolsum, nextcolsum; 321 #else 322 register INT32 thiscolsum, lastcolsum, nextcolsum; 323 #endif 324 register 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 /* Special case for first column */ 339 thiscolsum = GETJSAMPLE(*inptr0++) * 3 + GETJSAMPLE(*inptr1++); 340 nextcolsum = GETJSAMPLE(*inptr0++) * 3 + GETJSAMPLE(*inptr1++); 341 *outptr++ = (JSAMPLE) ((thiscolsum * 4 + 8) >> 4); 342 *outptr++ = (JSAMPLE) ((thiscolsum * 3 + nextcolsum + 7) >> 4); 343 lastcolsum = thiscolsum; thiscolsum = nextcolsum; 344 345 for (colctr = compptr->downsampled_width - 2; colctr > 0; colctr--) { 346 /* General case: 3/4 * nearer pixel + 1/4 * further pixel in each */ 347 /* dimension, thus 9/16, 3/16, 3/16, 1/16 overall */ 348 nextcolsum = GETJSAMPLE(*inptr0++) * 3 + GETJSAMPLE(*inptr1++); 349 *outptr++ = (JSAMPLE) ((thiscolsum * 3 + lastcolsum + 8) >> 4); 350 *outptr++ = (JSAMPLE) ((thiscolsum * 3 + nextcolsum + 7) >> 4); 351 lastcolsum = thiscolsum; thiscolsum = nextcolsum; 352 } 353 354 /* Special case for last column */ 355 *outptr++ = (JSAMPLE) ((thiscolsum * 3 + lastcolsum + 8) >> 4); 356 *outptr++ = (JSAMPLE) ((thiscolsum * 4 + 7) >> 4); 357 } 358 inrow++; 359 } 360 } 361 362 363 /* 364 * Module initialization routine for upsampling. 365 */ 366 367 GLOBAL(void) 368 jinit_upsampler (j_decompress_ptr cinfo) 369 { 370 my_upsample_ptr upsample; 371 int ci; 372 jpeg_component_info * compptr; 373 boolean need_buffer, do_fancy; 374 int h_in_group, v_in_group, h_out_group, v_out_group; 375 376 if (!cinfo->master->jinit_upsampler_no_alloc) { 377 upsample = (my_upsample_ptr) 378 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, 379 sizeof(my_upsampler)); 380 cinfo->upsample = (struct jpeg_upsampler *) upsample; 381 upsample->pub.start_pass = start_pass_upsample; 382 upsample->pub.upsample = sep_upsample; 383 upsample->pub.need_context_rows = FALSE; /* until we find out differently */ 384 } else 385 upsample = (my_upsample_ptr) cinfo->upsample; 386 387 if (cinfo->CCIR601_sampling) /* this isn't supported */ 388 ERREXIT(cinfo, JERR_CCIR601_NOTIMPL); 389 390 /* jdmainct.c doesn't support context rows when min_DCT_scaled_size = 1, 391 * so don't ask for it. 392 */ 393 do_fancy = cinfo->do_fancy_upsampling && cinfo->_min_DCT_scaled_size > 1; 394 395 /* Verify we can handle the sampling factors, select per-component methods, 396 * and create storage as needed. 397 */ 398 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; 399 ci++, compptr++) { 400 /* Compute size of an "input group" after IDCT scaling. This many samples 401 * are to be converted to max_h_samp_factor * max_v_samp_factor pixels. 402 */ 403 h_in_group = (compptr->h_samp_factor * compptr->_DCT_scaled_size) / 404 cinfo->_min_DCT_scaled_size; 405 v_in_group = (compptr->v_samp_factor * compptr->_DCT_scaled_size) / 406 cinfo->_min_DCT_scaled_size; 407 h_out_group = cinfo->max_h_samp_factor; 408 v_out_group = cinfo->max_v_samp_factor; 409 upsample->rowgroup_height[ci] = v_in_group; /* save for use later */ 410 need_buffer = TRUE; 411 if (! compptr->component_needed) { 412 /* Don't bother to upsample an uninteresting component. */ 413 upsample->methods[ci] = noop_upsample; 414 need_buffer = FALSE; 415 } else if (h_in_group == h_out_group && v_in_group == v_out_group) { 416 /* Fullsize components can be processed without any work. */ 417 upsample->methods[ci] = fullsize_upsample; 418 need_buffer = FALSE; 419 } else if (h_in_group * 2 == h_out_group && 420 v_in_group == v_out_group) { 421 /* Special cases for 2h1v upsampling */ 422 if (do_fancy && compptr->downsampled_width > 2) { 423 if (jsimd_can_h2v1_fancy_upsample()) 424 upsample->methods[ci] = jsimd_h2v1_fancy_upsample; 425 else 426 upsample->methods[ci] = h2v1_fancy_upsample; 427 } else { 428 if (jsimd_can_h2v1_upsample()) 429 upsample->methods[ci] = jsimd_h2v1_upsample; 430 else 431 upsample->methods[ci] = h2v1_upsample; 432 } 433 } else if (h_in_group * 2 == h_out_group && 434 v_in_group * 2 == v_out_group) { 435 /* Special cases for 2h2v upsampling */ 436 if (do_fancy && compptr->downsampled_width > 2) { 437 if (jsimd_can_h2v2_fancy_upsample()) 438 upsample->methods[ci] = jsimd_h2v2_fancy_upsample; 439 else 440 upsample->methods[ci] = h2v2_fancy_upsample; 441 upsample->pub.need_context_rows = TRUE; 442 } else { 443 if (jsimd_can_h2v2_upsample()) 444 upsample->methods[ci] = jsimd_h2v2_upsample; 445 else 446 upsample->methods[ci] = h2v2_upsample; 447 } 448 } else if ((h_out_group % h_in_group) == 0 && 449 (v_out_group % v_in_group) == 0) { 450 /* Generic integral-factors upsampling method */ 451 #if defined(__mips__) 452 if (jsimd_can_int_upsample()) 453 upsample->methods[ci] = jsimd_int_upsample; 454 else 455 #endif 456 upsample->methods[ci] = int_upsample; 457 upsample->h_expand[ci] = (UINT8) (h_out_group / h_in_group); 458 upsample->v_expand[ci] = (UINT8) (v_out_group / v_in_group); 459 } else 460 ERREXIT(cinfo, JERR_FRACT_SAMPLE_NOTIMPL); 461 if (need_buffer && !cinfo->master->jinit_upsampler_no_alloc) { 462 upsample->color_buf[ci] = (*cinfo->mem->alloc_sarray) 463 ((j_common_ptr) cinfo, JPOOL_IMAGE, 464 (JDIMENSION) jround_up((long) cinfo->output_width, 465 (long) cinfo->max_h_samp_factor), 466 (JDIMENSION) cinfo->max_v_samp_factor); 467 } 468 } 469 } 470
