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annotate libs/libjpeg/jdsample.c @ 0:b2f14e535253

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author John Tsiombikas <nuclear@member.fsf.org>
date Sat, 01 Feb 2014 19:58:19 +0200
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nuclear@0 1 /*
nuclear@0 2 * jdsample.c
nuclear@0 3 *
nuclear@0 4 * Copyright (C) 1991-1996, Thomas G. Lane.
nuclear@0 5 * This file is part of the Independent JPEG Group's software.
nuclear@0 6 * For conditions of distribution and use, see the accompanying README file.
nuclear@0 7 *
nuclear@0 8 * This file contains upsampling routines.
nuclear@0 9 *
nuclear@0 10 * Upsampling input data is counted in "row groups". A row group
nuclear@0 11 * is defined to be (v_samp_factor * DCT_scaled_size / min_DCT_scaled_size)
nuclear@0 12 * sample rows of each component. Upsampling will normally produce
nuclear@0 13 * max_v_samp_factor pixel rows from each row group (but this could vary
nuclear@0 14 * if the upsampler is applying a scale factor of its own).
nuclear@0 15 *
nuclear@0 16 * An excellent reference for image resampling is
nuclear@0 17 * Digital Image Warping, George Wolberg, 1990.
nuclear@0 18 * Pub. by IEEE Computer Society Press, Los Alamitos, CA. ISBN 0-8186-8944-7.
nuclear@0 19 */
nuclear@0 20
nuclear@0 21 #define JPEG_INTERNALS
nuclear@0 22 #include "jinclude.h"
nuclear@0 23 #include "jpeglib.h"
nuclear@0 24
nuclear@0 25
nuclear@0 26 /* Pointer to routine to upsample a single component */
nuclear@0 27 typedef JMETHOD(void, upsample1_ptr,
nuclear@0 28 (j_decompress_ptr cinfo, jpeg_component_info * compptr,
nuclear@0 29 JSAMPARRAY input_data, JSAMPARRAY * output_data_ptr));
nuclear@0 30
nuclear@0 31 /* Private subobject */
nuclear@0 32
nuclear@0 33 typedef struct {
nuclear@0 34 struct jpeg_upsampler pub; /* public fields */
nuclear@0 35
nuclear@0 36 /* Color conversion buffer. When using separate upsampling and color
nuclear@0 37 * conversion steps, this buffer holds one upsampled row group until it
nuclear@0 38 * has been color converted and output.
nuclear@0 39 * Note: we do not allocate any storage for component(s) which are full-size,
nuclear@0 40 * ie do not need rescaling. The corresponding entry of color_buf[] is
nuclear@0 41 * simply set to point to the input data array, thereby avoiding copying.
nuclear@0 42 */
nuclear@0 43 JSAMPARRAY color_buf[MAX_COMPONENTS];
nuclear@0 44
nuclear@0 45 /* Per-component upsampling method pointers */
nuclear@0 46 upsample1_ptr methods[MAX_COMPONENTS];
nuclear@0 47
nuclear@0 48 int next_row_out; /* counts rows emitted from color_buf */
nuclear@0 49 JDIMENSION rows_to_go; /* counts rows remaining in image */
nuclear@0 50
nuclear@0 51 /* Height of an input row group for each component. */
nuclear@0 52 int rowgroup_height[MAX_COMPONENTS];
nuclear@0 53
nuclear@0 54 /* These arrays save pixel expansion factors so that int_expand need not
nuclear@0 55 * recompute them each time. They are unused for other upsampling methods.
nuclear@0 56 */
nuclear@0 57 UINT8 h_expand[MAX_COMPONENTS];
nuclear@0 58 UINT8 v_expand[MAX_COMPONENTS];
nuclear@0 59 } my_upsampler;
nuclear@0 60
nuclear@0 61 typedef my_upsampler * my_upsample_ptr;
nuclear@0 62
nuclear@0 63
nuclear@0 64 /*
nuclear@0 65 * Initialize for an upsampling pass.
nuclear@0 66 */
nuclear@0 67
nuclear@0 68 METHODDEF(void)
nuclear@0 69 start_pass_upsample (j_decompress_ptr cinfo)
nuclear@0 70 {
nuclear@0 71 my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample;
nuclear@0 72
nuclear@0 73 /* Mark the conversion buffer empty */
nuclear@0 74 upsample->next_row_out = cinfo->max_v_samp_factor;
nuclear@0 75 /* Initialize total-height counter for detecting bottom of image */
nuclear@0 76 upsample->rows_to_go = cinfo->output_height;
nuclear@0 77 }
nuclear@0 78
nuclear@0 79
nuclear@0 80 /*
nuclear@0 81 * Control routine to do upsampling (and color conversion).
nuclear@0 82 *
nuclear@0 83 * In this version we upsample each component independently.
nuclear@0 84 * We upsample one row group into the conversion buffer, then apply
nuclear@0 85 * color conversion a row at a time.
nuclear@0 86 */
nuclear@0 87
nuclear@0 88 METHODDEF(void)
nuclear@0 89 sep_upsample (j_decompress_ptr cinfo,
nuclear@0 90 JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr,
nuclear@0 91 JDIMENSION in_row_groups_avail,
nuclear@0 92 JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,
nuclear@0 93 JDIMENSION out_rows_avail)
nuclear@0 94 {
nuclear@0 95 my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample;
nuclear@0 96 int ci;
nuclear@0 97 jpeg_component_info * compptr;
nuclear@0 98 JDIMENSION num_rows;
nuclear@0 99
nuclear@0 100 /* Fill the conversion buffer, if it's empty */
nuclear@0 101 if (upsample->next_row_out >= cinfo->max_v_samp_factor) {
nuclear@0 102 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
nuclear@0 103 ci++, compptr++) {
nuclear@0 104 /* Invoke per-component upsample method. Notice we pass a POINTER
nuclear@0 105 * to color_buf[ci], so that fullsize_upsample can change it.
nuclear@0 106 */
nuclear@0 107 (*upsample->methods[ci]) (cinfo, compptr,
nuclear@0 108 input_buf[ci] + (*in_row_group_ctr * upsample->rowgroup_height[ci]),
nuclear@0 109 upsample->color_buf + ci);
nuclear@0 110 }
nuclear@0 111 upsample->next_row_out = 0;
nuclear@0 112 }
nuclear@0 113
nuclear@0 114 /* Color-convert and emit rows */
nuclear@0 115
nuclear@0 116 /* How many we have in the buffer: */
nuclear@0 117 num_rows = (JDIMENSION) (cinfo->max_v_samp_factor - upsample->next_row_out);
nuclear@0 118 /* Not more than the distance to the end of the image. Need this test
nuclear@0 119 * in case the image height is not a multiple of max_v_samp_factor:
nuclear@0 120 */
nuclear@0 121 if (num_rows > upsample->rows_to_go)
nuclear@0 122 num_rows = upsample->rows_to_go;
nuclear@0 123 /* And not more than what the client can accept: */
nuclear@0 124 out_rows_avail -= *out_row_ctr;
nuclear@0 125 if (num_rows > out_rows_avail)
nuclear@0 126 num_rows = out_rows_avail;
nuclear@0 127
nuclear@0 128 (*cinfo->cconvert->color_convert) (cinfo, upsample->color_buf,
nuclear@0 129 (JDIMENSION) upsample->next_row_out,
nuclear@0 130 output_buf + *out_row_ctr,
nuclear@0 131 (int) num_rows);
nuclear@0 132
nuclear@0 133 /* Adjust counts */
nuclear@0 134 *out_row_ctr += num_rows;
nuclear@0 135 upsample->rows_to_go -= num_rows;
nuclear@0 136 upsample->next_row_out += num_rows;
nuclear@0 137 /* When the buffer is emptied, declare this input row group consumed */
nuclear@0 138 if (upsample->next_row_out >= cinfo->max_v_samp_factor)
nuclear@0 139 (*in_row_group_ctr)++;
nuclear@0 140 }
nuclear@0 141
nuclear@0 142
nuclear@0 143 /*
nuclear@0 144 * These are the routines invoked by sep_upsample to upsample pixel values
nuclear@0 145 * of a single component. One row group is processed per call.
nuclear@0 146 */
nuclear@0 147
nuclear@0 148
nuclear@0 149 /*
nuclear@0 150 * For full-size components, we just make color_buf[ci] point at the
nuclear@0 151 * input buffer, and thus avoid copying any data. Note that this is
nuclear@0 152 * safe only because sep_upsample doesn't declare the input row group
nuclear@0 153 * "consumed" until we are done color converting and emitting it.
nuclear@0 154 */
nuclear@0 155
nuclear@0 156 METHODDEF(void)
nuclear@0 157 fullsize_upsample (j_decompress_ptr cinfo, jpeg_component_info * compptr,
nuclear@0 158 JSAMPARRAY input_data, JSAMPARRAY * output_data_ptr)
nuclear@0 159 {
nuclear@0 160 *output_data_ptr = input_data;
nuclear@0 161 }
nuclear@0 162
nuclear@0 163
nuclear@0 164 /*
nuclear@0 165 * This is a no-op version used for "uninteresting" components.
nuclear@0 166 * These components will not be referenced by color conversion.
nuclear@0 167 */
nuclear@0 168
nuclear@0 169 METHODDEF(void)
nuclear@0 170 noop_upsample (j_decompress_ptr cinfo, jpeg_component_info * compptr,
nuclear@0 171 JSAMPARRAY input_data, JSAMPARRAY * output_data_ptr)
nuclear@0 172 {
nuclear@0 173 *output_data_ptr = NULL; /* safety check */
nuclear@0 174 }
nuclear@0 175
nuclear@0 176
nuclear@0 177 /*
nuclear@0 178 * This version handles any integral sampling ratios.
nuclear@0 179 * This is not used for typical JPEG files, so it need not be fast.
nuclear@0 180 * Nor, for that matter, is it particularly accurate: the algorithm is
nuclear@0 181 * simple replication of the input pixel onto the corresponding output
nuclear@0 182 * pixels. The hi-falutin sampling literature refers to this as a
nuclear@0 183 * "box filter". A box filter tends to introduce visible artifacts,
nuclear@0 184 * so if you are actually going to use 3:1 or 4:1 sampling ratios
nuclear@0 185 * you would be well advised to improve this code.
nuclear@0 186 */
nuclear@0 187
nuclear@0 188 METHODDEF(void)
nuclear@0 189 int_upsample (j_decompress_ptr cinfo, jpeg_component_info * compptr,
nuclear@0 190 JSAMPARRAY input_data, JSAMPARRAY * output_data_ptr)
nuclear@0 191 {
nuclear@0 192 my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample;
nuclear@0 193 JSAMPARRAY output_data = *output_data_ptr;
nuclear@0 194 register JSAMPROW inptr, outptr;
nuclear@0 195 register JSAMPLE invalue;
nuclear@0 196 register int h;
nuclear@0 197 JSAMPROW outend;
nuclear@0 198 int h_expand, v_expand;
nuclear@0 199 int inrow, outrow;
nuclear@0 200
nuclear@0 201 h_expand = upsample->h_expand[compptr->component_index];
nuclear@0 202 v_expand = upsample->v_expand[compptr->component_index];
nuclear@0 203
nuclear@0 204 inrow = outrow = 0;
nuclear@0 205 while (outrow < cinfo->max_v_samp_factor) {
nuclear@0 206 /* Generate one output row with proper horizontal expansion */
nuclear@0 207 inptr = input_data[inrow];
nuclear@0 208 outptr = output_data[outrow];
nuclear@0 209 outend = outptr + cinfo->output_width;
nuclear@0 210 while (outptr < outend) {
nuclear@0 211 invalue = *inptr++; /* don't need GETJSAMPLE() here */
nuclear@0 212 for (h = h_expand; h > 0; h--) {
nuclear@0 213 *outptr++ = invalue;
nuclear@0 214 }
nuclear@0 215 }
nuclear@0 216 /* Generate any additional output rows by duplicating the first one */
nuclear@0 217 if (v_expand > 1) {
nuclear@0 218 jcopy_sample_rows(output_data, outrow, output_data, outrow+1,
nuclear@0 219 v_expand-1, cinfo->output_width);
nuclear@0 220 }
nuclear@0 221 inrow++;
nuclear@0 222 outrow += v_expand;
nuclear@0 223 }
nuclear@0 224 }
nuclear@0 225
nuclear@0 226
nuclear@0 227 /*
nuclear@0 228 * Fast processing for the common case of 2:1 horizontal and 1:1 vertical.
nuclear@0 229 * It's still a box filter.
nuclear@0 230 */
nuclear@0 231
nuclear@0 232 METHODDEF(void)
nuclear@0 233 h2v1_upsample (j_decompress_ptr cinfo, jpeg_component_info * compptr,
nuclear@0 234 JSAMPARRAY input_data, JSAMPARRAY * output_data_ptr)
nuclear@0 235 {
nuclear@0 236 JSAMPARRAY output_data = *output_data_ptr;
nuclear@0 237 register JSAMPROW inptr, outptr;
nuclear@0 238 register JSAMPLE invalue;
nuclear@0 239 JSAMPROW outend;
nuclear@0 240 int inrow;
nuclear@0 241
nuclear@0 242 for (inrow = 0; inrow < cinfo->max_v_samp_factor; inrow++) {
nuclear@0 243 inptr = input_data[inrow];
nuclear@0 244 outptr = output_data[inrow];
nuclear@0 245 outend = outptr + cinfo->output_width;
nuclear@0 246 while (outptr < outend) {
nuclear@0 247 invalue = *inptr++; /* don't need GETJSAMPLE() here */
nuclear@0 248 *outptr++ = invalue;
nuclear@0 249 *outptr++ = invalue;
nuclear@0 250 }
nuclear@0 251 }
nuclear@0 252 }
nuclear@0 253
nuclear@0 254
nuclear@0 255 /*
nuclear@0 256 * Fast processing for the common case of 2:1 horizontal and 2:1 vertical.
nuclear@0 257 * It's still a box filter.
nuclear@0 258 */
nuclear@0 259
nuclear@0 260 METHODDEF(void)
nuclear@0 261 h2v2_upsample (j_decompress_ptr cinfo, jpeg_component_info * compptr,
nuclear@0 262 JSAMPARRAY input_data, JSAMPARRAY * output_data_ptr)
nuclear@0 263 {
nuclear@0 264 JSAMPARRAY output_data = *output_data_ptr;
nuclear@0 265 register JSAMPROW inptr, outptr;
nuclear@0 266 register JSAMPLE invalue;
nuclear@0 267 JSAMPROW outend;
nuclear@0 268 int inrow, outrow;
nuclear@0 269
nuclear@0 270 inrow = outrow = 0;
nuclear@0 271 while (outrow < cinfo->max_v_samp_factor) {
nuclear@0 272 inptr = input_data[inrow];
nuclear@0 273 outptr = output_data[outrow];
nuclear@0 274 outend = outptr + cinfo->output_width;
nuclear@0 275 while (outptr < outend) {
nuclear@0 276 invalue = *inptr++; /* don't need GETJSAMPLE() here */
nuclear@0 277 *outptr++ = invalue;
nuclear@0 278 *outptr++ = invalue;
nuclear@0 279 }
nuclear@0 280 jcopy_sample_rows(output_data, outrow, output_data, outrow+1,
nuclear@0 281 1, cinfo->output_width);
nuclear@0 282 inrow++;
nuclear@0 283 outrow += 2;
nuclear@0 284 }
nuclear@0 285 }
nuclear@0 286
nuclear@0 287
nuclear@0 288 /*
nuclear@0 289 * Fancy processing for the common case of 2:1 horizontal and 1:1 vertical.
nuclear@0 290 *
nuclear@0 291 * The upsampling algorithm is linear interpolation between pixel centers,
nuclear@0 292 * also known as a "triangle filter". This is a good compromise between
nuclear@0 293 * speed and visual quality. The centers of the output pixels are 1/4 and 3/4
nuclear@0 294 * of the way between input pixel centers.
nuclear@0 295 *
nuclear@0 296 * A note about the "bias" calculations: when rounding fractional values to
nuclear@0 297 * integer, we do not want to always round 0.5 up to the next integer.
nuclear@0 298 * If we did that, we'd introduce a noticeable bias towards larger values.
nuclear@0 299 * Instead, this code is arranged so that 0.5 will be rounded up or down at
nuclear@0 300 * alternate pixel locations (a simple ordered dither pattern).
nuclear@0 301 */
nuclear@0 302
nuclear@0 303 METHODDEF(void)
nuclear@0 304 h2v1_fancy_upsample (j_decompress_ptr cinfo, jpeg_component_info * compptr,
nuclear@0 305 JSAMPARRAY input_data, JSAMPARRAY * output_data_ptr)
nuclear@0 306 {
nuclear@0 307 JSAMPARRAY output_data = *output_data_ptr;
nuclear@0 308 register JSAMPROW inptr, outptr;
nuclear@0 309 register int invalue;
nuclear@0 310 register JDIMENSION colctr;
nuclear@0 311 int inrow;
nuclear@0 312
nuclear@0 313 for (inrow = 0; inrow < cinfo->max_v_samp_factor; inrow++) {
nuclear@0 314 inptr = input_data[inrow];
nuclear@0 315 outptr = output_data[inrow];
nuclear@0 316 /* Special case for first column */
nuclear@0 317 invalue = GETJSAMPLE(*inptr++);
nuclear@0 318 *outptr++ = (JSAMPLE) invalue;
nuclear@0 319 *outptr++ = (JSAMPLE) ((invalue * 3 + GETJSAMPLE(*inptr) + 2) >> 2);
nuclear@0 320
nuclear@0 321 for (colctr = compptr->downsampled_width - 2; colctr > 0; colctr--) {
nuclear@0 322 /* General case: 3/4 * nearer pixel + 1/4 * further pixel */
nuclear@0 323 invalue = GETJSAMPLE(*inptr++) * 3;
nuclear@0 324 *outptr++ = (JSAMPLE) ((invalue + GETJSAMPLE(inptr[-2]) + 1) >> 2);
nuclear@0 325 *outptr++ = (JSAMPLE) ((invalue + GETJSAMPLE(*inptr) + 2) >> 2);
nuclear@0 326 }
nuclear@0 327
nuclear@0 328 /* Special case for last column */
nuclear@0 329 invalue = GETJSAMPLE(*inptr);
nuclear@0 330 *outptr++ = (JSAMPLE) ((invalue * 3 + GETJSAMPLE(inptr[-1]) + 1) >> 2);
nuclear@0 331 *outptr++ = (JSAMPLE) invalue;
nuclear@0 332 }
nuclear@0 333 }
nuclear@0 334
nuclear@0 335
nuclear@0 336 /*
nuclear@0 337 * Fancy processing for the common case of 2:1 horizontal and 2:1 vertical.
nuclear@0 338 * Again a triangle filter; see comments for h2v1 case, above.
nuclear@0 339 *
nuclear@0 340 * It is OK for us to reference the adjacent input rows because we demanded
nuclear@0 341 * context from the main buffer controller (see initialization code).
nuclear@0 342 */
nuclear@0 343
nuclear@0 344 METHODDEF(void)
nuclear@0 345 h2v2_fancy_upsample (j_decompress_ptr cinfo, jpeg_component_info * compptr,
nuclear@0 346 JSAMPARRAY input_data, JSAMPARRAY * output_data_ptr)
nuclear@0 347 {
nuclear@0 348 JSAMPARRAY output_data = *output_data_ptr;
nuclear@0 349 register JSAMPROW inptr0, inptr1, outptr;
nuclear@0 350 #if BITS_IN_JSAMPLE == 8
nuclear@0 351 register int thiscolsum, lastcolsum, nextcolsum;
nuclear@0 352 #else
nuclear@0 353 register INT32 thiscolsum, lastcolsum, nextcolsum;
nuclear@0 354 #endif
nuclear@0 355 register JDIMENSION colctr;
nuclear@0 356 int inrow, outrow, v;
nuclear@0 357
nuclear@0 358 inrow = outrow = 0;
nuclear@0 359 while (outrow < cinfo->max_v_samp_factor) {
nuclear@0 360 for (v = 0; v < 2; v++) {
nuclear@0 361 /* inptr0 points to nearest input row, inptr1 points to next nearest */
nuclear@0 362 inptr0 = input_data[inrow];
nuclear@0 363 if (v == 0) /* next nearest is row above */
nuclear@0 364 inptr1 = input_data[inrow-1];
nuclear@0 365 else /* next nearest is row below */
nuclear@0 366 inptr1 = input_data[inrow+1];
nuclear@0 367 outptr = output_data[outrow++];
nuclear@0 368
nuclear@0 369 /* Special case for first column */
nuclear@0 370 thiscolsum = GETJSAMPLE(*inptr0++) * 3 + GETJSAMPLE(*inptr1++);
nuclear@0 371 nextcolsum = GETJSAMPLE(*inptr0++) * 3 + GETJSAMPLE(*inptr1++);
nuclear@0 372 *outptr++ = (JSAMPLE) ((thiscolsum * 4 + 8) >> 4);
nuclear@0 373 *outptr++ = (JSAMPLE) ((thiscolsum * 3 + nextcolsum + 7) >> 4);
nuclear@0 374 lastcolsum = thiscolsum; thiscolsum = nextcolsum;
nuclear@0 375
nuclear@0 376 for (colctr = compptr->downsampled_width - 2; colctr > 0; colctr--) {
nuclear@0 377 /* General case: 3/4 * nearer pixel + 1/4 * further pixel in each */
nuclear@0 378 /* dimension, thus 9/16, 3/16, 3/16, 1/16 overall */
nuclear@0 379 nextcolsum = GETJSAMPLE(*inptr0++) * 3 + GETJSAMPLE(*inptr1++);
nuclear@0 380 *outptr++ = (JSAMPLE) ((thiscolsum * 3 + lastcolsum + 8) >> 4);
nuclear@0 381 *outptr++ = (JSAMPLE) ((thiscolsum * 3 + nextcolsum + 7) >> 4);
nuclear@0 382 lastcolsum = thiscolsum; thiscolsum = nextcolsum;
nuclear@0 383 }
nuclear@0 384
nuclear@0 385 /* Special case for last column */
nuclear@0 386 *outptr++ = (JSAMPLE) ((thiscolsum * 3 + lastcolsum + 8) >> 4);
nuclear@0 387 *outptr++ = (JSAMPLE) ((thiscolsum * 4 + 7) >> 4);
nuclear@0 388 }
nuclear@0 389 inrow++;
nuclear@0 390 }
nuclear@0 391 }
nuclear@0 392
nuclear@0 393
nuclear@0 394 /*
nuclear@0 395 * Module initialization routine for upsampling.
nuclear@0 396 */
nuclear@0 397
nuclear@0 398 GLOBAL(void)
nuclear@0 399 jinit_upsampler (j_decompress_ptr cinfo)
nuclear@0 400 {
nuclear@0 401 my_upsample_ptr upsample;
nuclear@0 402 int ci;
nuclear@0 403 jpeg_component_info * compptr;
nuclear@0 404 boolean need_buffer, do_fancy;
nuclear@0 405 int h_in_group, v_in_group, h_out_group, v_out_group;
nuclear@0 406
nuclear@0 407 upsample = (my_upsample_ptr)
nuclear@0 408 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
nuclear@0 409 SIZEOF(my_upsampler));
nuclear@0 410 cinfo->upsample = (struct jpeg_upsampler *) upsample;
nuclear@0 411 upsample->pub.start_pass = start_pass_upsample;
nuclear@0 412 upsample->pub.upsample = sep_upsample;
nuclear@0 413 upsample->pub.need_context_rows = FALSE; /* until we find out differently */
nuclear@0 414
nuclear@0 415 if (cinfo->CCIR601_sampling) /* this isn't supported */
nuclear@0 416 ERREXIT(cinfo, JERR_CCIR601_NOTIMPL);
nuclear@0 417
nuclear@0 418 /* jdmainct.c doesn't support context rows when min_DCT_scaled_size = 1,
nuclear@0 419 * so don't ask for it.
nuclear@0 420 */
nuclear@0 421 do_fancy = cinfo->do_fancy_upsampling && cinfo->min_DCT_scaled_size > 1;
nuclear@0 422
nuclear@0 423 /* Verify we can handle the sampling factors, select per-component methods,
nuclear@0 424 * and create storage as needed.
nuclear@0 425 */
nuclear@0 426 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
nuclear@0 427 ci++, compptr++) {
nuclear@0 428 /* Compute size of an "input group" after IDCT scaling. This many samples
nuclear@0 429 * are to be converted to max_h_samp_factor * max_v_samp_factor pixels.
nuclear@0 430 */
nuclear@0 431 h_in_group = (compptr->h_samp_factor * compptr->DCT_scaled_size) /
nuclear@0 432 cinfo->min_DCT_scaled_size;
nuclear@0 433 v_in_group = (compptr->v_samp_factor * compptr->DCT_scaled_size) /
nuclear@0 434 cinfo->min_DCT_scaled_size;
nuclear@0 435 h_out_group = cinfo->max_h_samp_factor;
nuclear@0 436 v_out_group = cinfo->max_v_samp_factor;
nuclear@0 437 upsample->rowgroup_height[ci] = v_in_group; /* save for use later */
nuclear@0 438 need_buffer = TRUE;
nuclear@0 439 if (! compptr->component_needed) {
nuclear@0 440 /* Don't bother to upsample an uninteresting component. */
nuclear@0 441 upsample->methods[ci] = noop_upsample;
nuclear@0 442 need_buffer = FALSE;
nuclear@0 443 } else if (h_in_group == h_out_group && v_in_group == v_out_group) {
nuclear@0 444 /* Fullsize components can be processed without any work. */
nuclear@0 445 upsample->methods[ci] = fullsize_upsample;
nuclear@0 446 need_buffer = FALSE;
nuclear@0 447 } else if (h_in_group * 2 == h_out_group &&
nuclear@0 448 v_in_group == v_out_group) {
nuclear@0 449 /* Special cases for 2h1v upsampling */
nuclear@0 450 if (do_fancy && compptr->downsampled_width > 2)
nuclear@0 451 upsample->methods[ci] = h2v1_fancy_upsample;
nuclear@0 452 else
nuclear@0 453 upsample->methods[ci] = h2v1_upsample;
nuclear@0 454 } else if (h_in_group * 2 == h_out_group &&
nuclear@0 455 v_in_group * 2 == v_out_group) {
nuclear@0 456 /* Special cases for 2h2v upsampling */
nuclear@0 457 if (do_fancy && compptr->downsampled_width > 2) {
nuclear@0 458 upsample->methods[ci] = h2v2_fancy_upsample;
nuclear@0 459 upsample->pub.need_context_rows = TRUE;
nuclear@0 460 } else
nuclear@0 461 upsample->methods[ci] = h2v2_upsample;
nuclear@0 462 } else if ((h_out_group % h_in_group) == 0 &&
nuclear@0 463 (v_out_group % v_in_group) == 0) {
nuclear@0 464 /* Generic integral-factors upsampling method */
nuclear@0 465 upsample->methods[ci] = int_upsample;
nuclear@0 466 upsample->h_expand[ci] = (UINT8) (h_out_group / h_in_group);
nuclear@0 467 upsample->v_expand[ci] = (UINT8) (v_out_group / v_in_group);
nuclear@0 468 } else
nuclear@0 469 ERREXIT(cinfo, JERR_FRACT_SAMPLE_NOTIMPL);
nuclear@0 470 if (need_buffer) {
nuclear@0 471 upsample->color_buf[ci] = (*cinfo->mem->alloc_sarray)
nuclear@0 472 ((j_common_ptr) cinfo, JPOOL_IMAGE,
nuclear@0 473 (JDIMENSION) jround_up((long) cinfo->output_width,
nuclear@0 474 (long) cinfo->max_h_samp_factor),
nuclear@0 475 (JDIMENSION) cinfo->max_v_samp_factor);
nuclear@0 476 }
nuclear@0 477 }
nuclear@0 478 }