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annotate libs/libjpeg/jdsample.c @ 7:a3c4fcc9f8f3

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author John Tsiombikas <nuclear@member.fsf.org>
date Thu, 24 Sep 2015 06:49:25 +0300
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nuclear@2 1 /*
nuclear@2 2 * jdsample.c
nuclear@2 3 *
nuclear@2 4 * Copyright (C) 1991-1996, Thomas G. Lane.
nuclear@2 5 * This file is part of the Independent JPEG Group's software.
nuclear@2 6 * For conditions of distribution and use, see the accompanying README file.
nuclear@2 7 *
nuclear@2 8 * This file contains upsampling routines.
nuclear@2 9 *
nuclear@2 10 * Upsampling input data is counted in "row groups". A row group
nuclear@2 11 * is defined to be (v_samp_factor * DCT_scaled_size / min_DCT_scaled_size)
nuclear@2 12 * sample rows of each component. Upsampling will normally produce
nuclear@2 13 * max_v_samp_factor pixel rows from each row group (but this could vary
nuclear@2 14 * if the upsampler is applying a scale factor of its own).
nuclear@2 15 *
nuclear@2 16 * An excellent reference for image resampling is
nuclear@2 17 * Digital Image Warping, George Wolberg, 1990.
nuclear@2 18 * Pub. by IEEE Computer Society Press, Los Alamitos, CA. ISBN 0-8186-8944-7.
nuclear@2 19 */
nuclear@2 20
nuclear@2 21 #define JPEG_INTERNALS
nuclear@2 22 #include "jinclude.h"
nuclear@2 23 #include "jpeglib.h"
nuclear@2 24
nuclear@2 25
nuclear@2 26 /* Pointer to routine to upsample a single component */
nuclear@2 27 typedef JMETHOD(void, upsample1_ptr,
nuclear@2 28 (j_decompress_ptr cinfo, jpeg_component_info * compptr,
nuclear@2 29 JSAMPARRAY input_data, JSAMPARRAY * output_data_ptr));
nuclear@2 30
nuclear@2 31 /* Private subobject */
nuclear@2 32
nuclear@2 33 typedef struct {
nuclear@2 34 struct jpeg_upsampler pub; /* public fields */
nuclear@2 35
nuclear@2 36 /* Color conversion buffer. When using separate upsampling and color
nuclear@2 37 * conversion steps, this buffer holds one upsampled row group until it
nuclear@2 38 * has been color converted and output.
nuclear@2 39 * Note: we do not allocate any storage for component(s) which are full-size,
nuclear@2 40 * ie do not need rescaling. The corresponding entry of color_buf[] is
nuclear@2 41 * simply set to point to the input data array, thereby avoiding copying.
nuclear@2 42 */
nuclear@2 43 JSAMPARRAY color_buf[MAX_COMPONENTS];
nuclear@2 44
nuclear@2 45 /* Per-component upsampling method pointers */
nuclear@2 46 upsample1_ptr methods[MAX_COMPONENTS];
nuclear@2 47
nuclear@2 48 int next_row_out; /* counts rows emitted from color_buf */
nuclear@2 49 JDIMENSION rows_to_go; /* counts rows remaining in image */
nuclear@2 50
nuclear@2 51 /* Height of an input row group for each component. */
nuclear@2 52 int rowgroup_height[MAX_COMPONENTS];
nuclear@2 53
nuclear@2 54 /* These arrays save pixel expansion factors so that int_expand need not
nuclear@2 55 * recompute them each time. They are unused for other upsampling methods.
nuclear@2 56 */
nuclear@2 57 UINT8 h_expand[MAX_COMPONENTS];
nuclear@2 58 UINT8 v_expand[MAX_COMPONENTS];
nuclear@2 59 } my_upsampler;
nuclear@2 60
nuclear@2 61 typedef my_upsampler * my_upsample_ptr;
nuclear@2 62
nuclear@2 63
nuclear@2 64 /*
nuclear@2 65 * Initialize for an upsampling pass.
nuclear@2 66 */
nuclear@2 67
nuclear@2 68 METHODDEF(void)
nuclear@2 69 start_pass_upsample (j_decompress_ptr cinfo)
nuclear@2 70 {
nuclear@2 71 my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample;
nuclear@2 72
nuclear@2 73 /* Mark the conversion buffer empty */
nuclear@2 74 upsample->next_row_out = cinfo->max_v_samp_factor;
nuclear@2 75 /* Initialize total-height counter for detecting bottom of image */
nuclear@2 76 upsample->rows_to_go = cinfo->output_height;
nuclear@2 77 }
nuclear@2 78
nuclear@2 79
nuclear@2 80 /*
nuclear@2 81 * Control routine to do upsampling (and color conversion).
nuclear@2 82 *
nuclear@2 83 * In this version we upsample each component independently.
nuclear@2 84 * We upsample one row group into the conversion buffer, then apply
nuclear@2 85 * color conversion a row at a time.
nuclear@2 86 */
nuclear@2 87
nuclear@2 88 METHODDEF(void)
nuclear@2 89 sep_upsample (j_decompress_ptr cinfo,
nuclear@2 90 JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr,
nuclear@2 91 JDIMENSION in_row_groups_avail,
nuclear@2 92 JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,
nuclear@2 93 JDIMENSION out_rows_avail)
nuclear@2 94 {
nuclear@2 95 my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample;
nuclear@2 96 int ci;
nuclear@2 97 jpeg_component_info * compptr;
nuclear@2 98 JDIMENSION num_rows;
nuclear@2 99
nuclear@2 100 /* Fill the conversion buffer, if it's empty */
nuclear@2 101 if (upsample->next_row_out >= cinfo->max_v_samp_factor) {
nuclear@2 102 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
nuclear@2 103 ci++, compptr++) {
nuclear@2 104 /* Invoke per-component upsample method. Notice we pass a POINTER
nuclear@2 105 * to color_buf[ci], so that fullsize_upsample can change it.
nuclear@2 106 */
nuclear@2 107 (*upsample->methods[ci]) (cinfo, compptr,
nuclear@2 108 input_buf[ci] + (*in_row_group_ctr * upsample->rowgroup_height[ci]),
nuclear@2 109 upsample->color_buf + ci);
nuclear@2 110 }
nuclear@2 111 upsample->next_row_out = 0;
nuclear@2 112 }
nuclear@2 113
nuclear@2 114 /* Color-convert and emit rows */
nuclear@2 115
nuclear@2 116 /* How many we have in the buffer: */
nuclear@2 117 num_rows = (JDIMENSION) (cinfo->max_v_samp_factor - upsample->next_row_out);
nuclear@2 118 /* Not more than the distance to the end of the image. Need this test
nuclear@2 119 * in case the image height is not a multiple of max_v_samp_factor:
nuclear@2 120 */
nuclear@2 121 if (num_rows > upsample->rows_to_go)
nuclear@2 122 num_rows = upsample->rows_to_go;
nuclear@2 123 /* And not more than what the client can accept: */
nuclear@2 124 out_rows_avail -= *out_row_ctr;
nuclear@2 125 if (num_rows > out_rows_avail)
nuclear@2 126 num_rows = out_rows_avail;
nuclear@2 127
nuclear@2 128 (*cinfo->cconvert->color_convert) (cinfo, upsample->color_buf,
nuclear@2 129 (JDIMENSION) upsample->next_row_out,
nuclear@2 130 output_buf + *out_row_ctr,
nuclear@2 131 (int) num_rows);
nuclear@2 132
nuclear@2 133 /* Adjust counts */
nuclear@2 134 *out_row_ctr += num_rows;
nuclear@2 135 upsample->rows_to_go -= num_rows;
nuclear@2 136 upsample->next_row_out += num_rows;
nuclear@2 137 /* When the buffer is emptied, declare this input row group consumed */
nuclear@2 138 if (upsample->next_row_out >= cinfo->max_v_samp_factor)
nuclear@2 139 (*in_row_group_ctr)++;
nuclear@2 140 }
nuclear@2 141
nuclear@2 142
nuclear@2 143 /*
nuclear@2 144 * These are the routines invoked by sep_upsample to upsample pixel values
nuclear@2 145 * of a single component. One row group is processed per call.
nuclear@2 146 */
nuclear@2 147
nuclear@2 148
nuclear@2 149 /*
nuclear@2 150 * For full-size components, we just make color_buf[ci] point at the
nuclear@2 151 * input buffer, and thus avoid copying any data. Note that this is
nuclear@2 152 * safe only because sep_upsample doesn't declare the input row group
nuclear@2 153 * "consumed" until we are done color converting and emitting it.
nuclear@2 154 */
nuclear@2 155
nuclear@2 156 METHODDEF(void)
nuclear@2 157 fullsize_upsample (j_decompress_ptr cinfo, jpeg_component_info * compptr,
nuclear@2 158 JSAMPARRAY input_data, JSAMPARRAY * output_data_ptr)
nuclear@2 159 {
nuclear@2 160 *output_data_ptr = input_data;
nuclear@2 161 }
nuclear@2 162
nuclear@2 163
nuclear@2 164 /*
nuclear@2 165 * This is a no-op version used for "uninteresting" components.
nuclear@2 166 * These components will not be referenced by color conversion.
nuclear@2 167 */
nuclear@2 168
nuclear@2 169 METHODDEF(void)
nuclear@2 170 noop_upsample (j_decompress_ptr cinfo, jpeg_component_info * compptr,
nuclear@2 171 JSAMPARRAY input_data, JSAMPARRAY * output_data_ptr)
nuclear@2 172 {
nuclear@2 173 *output_data_ptr = NULL; /* safety check */
nuclear@2 174 }
nuclear@2 175
nuclear@2 176
nuclear@2 177 /*
nuclear@2 178 * This version handles any integral sampling ratios.
nuclear@2 179 * This is not used for typical JPEG files, so it need not be fast.
nuclear@2 180 * Nor, for that matter, is it particularly accurate: the algorithm is
nuclear@2 181 * simple replication of the input pixel onto the corresponding output
nuclear@2 182 * pixels. The hi-falutin sampling literature refers to this as a
nuclear@2 183 * "box filter". A box filter tends to introduce visible artifacts,
nuclear@2 184 * so if you are actually going to use 3:1 or 4:1 sampling ratios
nuclear@2 185 * you would be well advised to improve this code.
nuclear@2 186 */
nuclear@2 187
nuclear@2 188 METHODDEF(void)
nuclear@2 189 int_upsample (j_decompress_ptr cinfo, jpeg_component_info * compptr,
nuclear@2 190 JSAMPARRAY input_data, JSAMPARRAY * output_data_ptr)
nuclear@2 191 {
nuclear@2 192 my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample;
nuclear@2 193 JSAMPARRAY output_data = *output_data_ptr;
nuclear@2 194 register JSAMPROW inptr, outptr;
nuclear@2 195 register JSAMPLE invalue;
nuclear@2 196 register int h;
nuclear@2 197 JSAMPROW outend;
nuclear@2 198 int h_expand, v_expand;
nuclear@2 199 int inrow, outrow;
nuclear@2 200
nuclear@2 201 h_expand = upsample->h_expand[compptr->component_index];
nuclear@2 202 v_expand = upsample->v_expand[compptr->component_index];
nuclear@2 203
nuclear@2 204 inrow = outrow = 0;
nuclear@2 205 while (outrow < cinfo->max_v_samp_factor) {
nuclear@2 206 /* Generate one output row with proper horizontal expansion */
nuclear@2 207 inptr = input_data[inrow];
nuclear@2 208 outptr = output_data[outrow];
nuclear@2 209 outend = outptr + cinfo->output_width;
nuclear@2 210 while (outptr < outend) {
nuclear@2 211 invalue = *inptr++; /* don't need GETJSAMPLE() here */
nuclear@2 212 for (h = h_expand; h > 0; h--) {
nuclear@2 213 *outptr++ = invalue;
nuclear@2 214 }
nuclear@2 215 }
nuclear@2 216 /* Generate any additional output rows by duplicating the first one */
nuclear@2 217 if (v_expand > 1) {
nuclear@2 218 jcopy_sample_rows(output_data, outrow, output_data, outrow+1,
nuclear@2 219 v_expand-1, cinfo->output_width);
nuclear@2 220 }
nuclear@2 221 inrow++;
nuclear@2 222 outrow += v_expand;
nuclear@2 223 }
nuclear@2 224 }
nuclear@2 225
nuclear@2 226
nuclear@2 227 /*
nuclear@2 228 * Fast processing for the common case of 2:1 horizontal and 1:1 vertical.
nuclear@2 229 * It's still a box filter.
nuclear@2 230 */
nuclear@2 231
nuclear@2 232 METHODDEF(void)
nuclear@2 233 h2v1_upsample (j_decompress_ptr cinfo, jpeg_component_info * compptr,
nuclear@2 234 JSAMPARRAY input_data, JSAMPARRAY * output_data_ptr)
nuclear@2 235 {
nuclear@2 236 JSAMPARRAY output_data = *output_data_ptr;
nuclear@2 237 register JSAMPROW inptr, outptr;
nuclear@2 238 register JSAMPLE invalue;
nuclear@2 239 JSAMPROW outend;
nuclear@2 240 int inrow;
nuclear@2 241
nuclear@2 242 for (inrow = 0; inrow < cinfo->max_v_samp_factor; inrow++) {
nuclear@2 243 inptr = input_data[inrow];
nuclear@2 244 outptr = output_data[inrow];
nuclear@2 245 outend = outptr + cinfo->output_width;
nuclear@2 246 while (outptr < outend) {
nuclear@2 247 invalue = *inptr++; /* don't need GETJSAMPLE() here */
nuclear@2 248 *outptr++ = invalue;
nuclear@2 249 *outptr++ = invalue;
nuclear@2 250 }
nuclear@2 251 }
nuclear@2 252 }
nuclear@2 253
nuclear@2 254
nuclear@2 255 /*
nuclear@2 256 * Fast processing for the common case of 2:1 horizontal and 2:1 vertical.
nuclear@2 257 * It's still a box filter.
nuclear@2 258 */
nuclear@2 259
nuclear@2 260 METHODDEF(void)
nuclear@2 261 h2v2_upsample (j_decompress_ptr cinfo, jpeg_component_info * compptr,
nuclear@2 262 JSAMPARRAY input_data, JSAMPARRAY * output_data_ptr)
nuclear@2 263 {
nuclear@2 264 JSAMPARRAY output_data = *output_data_ptr;
nuclear@2 265 register JSAMPROW inptr, outptr;
nuclear@2 266 register JSAMPLE invalue;
nuclear@2 267 JSAMPROW outend;
nuclear@2 268 int inrow, outrow;
nuclear@2 269
nuclear@2 270 inrow = outrow = 0;
nuclear@2 271 while (outrow < cinfo->max_v_samp_factor) {
nuclear@2 272 inptr = input_data[inrow];
nuclear@2 273 outptr = output_data[outrow];
nuclear@2 274 outend = outptr + cinfo->output_width;
nuclear@2 275 while (outptr < outend) {
nuclear@2 276 invalue = *inptr++; /* don't need GETJSAMPLE() here */
nuclear@2 277 *outptr++ = invalue;
nuclear@2 278 *outptr++ = invalue;
nuclear@2 279 }
nuclear@2 280 jcopy_sample_rows(output_data, outrow, output_data, outrow+1,
nuclear@2 281 1, cinfo->output_width);
nuclear@2 282 inrow++;
nuclear@2 283 outrow += 2;
nuclear@2 284 }
nuclear@2 285 }
nuclear@2 286
nuclear@2 287
nuclear@2 288 /*
nuclear@2 289 * Fancy processing for the common case of 2:1 horizontal and 1:1 vertical.
nuclear@2 290 *
nuclear@2 291 * The upsampling algorithm is linear interpolation between pixel centers,
nuclear@2 292 * also known as a "triangle filter". This is a good compromise between
nuclear@2 293 * speed and visual quality. The centers of the output pixels are 1/4 and 3/4
nuclear@2 294 * of the way between input pixel centers.
nuclear@2 295 *
nuclear@2 296 * A note about the "bias" calculations: when rounding fractional values to
nuclear@2 297 * integer, we do not want to always round 0.5 up to the next integer.
nuclear@2 298 * If we did that, we'd introduce a noticeable bias towards larger values.
nuclear@2 299 * Instead, this code is arranged so that 0.5 will be rounded up or down at
nuclear@2 300 * alternate pixel locations (a simple ordered dither pattern).
nuclear@2 301 */
nuclear@2 302
nuclear@2 303 METHODDEF(void)
nuclear@2 304 h2v1_fancy_upsample (j_decompress_ptr cinfo, jpeg_component_info * compptr,
nuclear@2 305 JSAMPARRAY input_data, JSAMPARRAY * output_data_ptr)
nuclear@2 306 {
nuclear@2 307 JSAMPARRAY output_data = *output_data_ptr;
nuclear@2 308 register JSAMPROW inptr, outptr;
nuclear@2 309 register int invalue;
nuclear@2 310 register JDIMENSION colctr;
nuclear@2 311 int inrow;
nuclear@2 312
nuclear@2 313 for (inrow = 0; inrow < cinfo->max_v_samp_factor; inrow++) {
nuclear@2 314 inptr = input_data[inrow];
nuclear@2 315 outptr = output_data[inrow];
nuclear@2 316 /* Special case for first column */
nuclear@2 317 invalue = GETJSAMPLE(*inptr++);
nuclear@2 318 *outptr++ = (JSAMPLE) invalue;
nuclear@2 319 *outptr++ = (JSAMPLE) ((invalue * 3 + GETJSAMPLE(*inptr) + 2) >> 2);
nuclear@2 320
nuclear@2 321 for (colctr = compptr->downsampled_width - 2; colctr > 0; colctr--) {
nuclear@2 322 /* General case: 3/4 * nearer pixel + 1/4 * further pixel */
nuclear@2 323 invalue = GETJSAMPLE(*inptr++) * 3;
nuclear@2 324 *outptr++ = (JSAMPLE) ((invalue + GETJSAMPLE(inptr[-2]) + 1) >> 2);
nuclear@2 325 *outptr++ = (JSAMPLE) ((invalue + GETJSAMPLE(*inptr) + 2) >> 2);
nuclear@2 326 }
nuclear@2 327
nuclear@2 328 /* Special case for last column */
nuclear@2 329 invalue = GETJSAMPLE(*inptr);
nuclear@2 330 *outptr++ = (JSAMPLE) ((invalue * 3 + GETJSAMPLE(inptr[-1]) + 1) >> 2);
nuclear@2 331 *outptr++ = (JSAMPLE) invalue;
nuclear@2 332 }
nuclear@2 333 }
nuclear@2 334
nuclear@2 335
nuclear@2 336 /*
nuclear@2 337 * Fancy processing for the common case of 2:1 horizontal and 2:1 vertical.
nuclear@2 338 * Again a triangle filter; see comments for h2v1 case, above.
nuclear@2 339 *
nuclear@2 340 * It is OK for us to reference the adjacent input rows because we demanded
nuclear@2 341 * context from the main buffer controller (see initialization code).
nuclear@2 342 */
nuclear@2 343
nuclear@2 344 METHODDEF(void)
nuclear@2 345 h2v2_fancy_upsample (j_decompress_ptr cinfo, jpeg_component_info * compptr,
nuclear@2 346 JSAMPARRAY input_data, JSAMPARRAY * output_data_ptr)
nuclear@2 347 {
nuclear@2 348 JSAMPARRAY output_data = *output_data_ptr;
nuclear@2 349 register JSAMPROW inptr0, inptr1, outptr;
nuclear@2 350 #if BITS_IN_JSAMPLE == 8
nuclear@2 351 register int thiscolsum, lastcolsum, nextcolsum;
nuclear@2 352 #else
nuclear@2 353 register INT32 thiscolsum, lastcolsum, nextcolsum;
nuclear@2 354 #endif
nuclear@2 355 register JDIMENSION colctr;
nuclear@2 356 int inrow, outrow, v;
nuclear@2 357
nuclear@2 358 inrow = outrow = 0;
nuclear@2 359 while (outrow < cinfo->max_v_samp_factor) {
nuclear@2 360 for (v = 0; v < 2; v++) {
nuclear@2 361 /* inptr0 points to nearest input row, inptr1 points to next nearest */
nuclear@2 362 inptr0 = input_data[inrow];
nuclear@2 363 if (v == 0) /* next nearest is row above */
nuclear@2 364 inptr1 = input_data[inrow-1];
nuclear@2 365 else /* next nearest is row below */
nuclear@2 366 inptr1 = input_data[inrow+1];
nuclear@2 367 outptr = output_data[outrow++];
nuclear@2 368
nuclear@2 369 /* Special case for first column */
nuclear@2 370 thiscolsum = GETJSAMPLE(*inptr0++) * 3 + GETJSAMPLE(*inptr1++);
nuclear@2 371 nextcolsum = GETJSAMPLE(*inptr0++) * 3 + GETJSAMPLE(*inptr1++);
nuclear@2 372 *outptr++ = (JSAMPLE) ((thiscolsum * 4 + 8) >> 4);
nuclear@2 373 *outptr++ = (JSAMPLE) ((thiscolsum * 3 + nextcolsum + 7) >> 4);
nuclear@2 374 lastcolsum = thiscolsum; thiscolsum = nextcolsum;
nuclear@2 375
nuclear@2 376 for (colctr = compptr->downsampled_width - 2; colctr > 0; colctr--) {
nuclear@2 377 /* General case: 3/4 * nearer pixel + 1/4 * further pixel in each */
nuclear@2 378 /* dimension, thus 9/16, 3/16, 3/16, 1/16 overall */
nuclear@2 379 nextcolsum = GETJSAMPLE(*inptr0++) * 3 + GETJSAMPLE(*inptr1++);
nuclear@2 380 *outptr++ = (JSAMPLE) ((thiscolsum * 3 + lastcolsum + 8) >> 4);
nuclear@2 381 *outptr++ = (JSAMPLE) ((thiscolsum * 3 + nextcolsum + 7) >> 4);
nuclear@2 382 lastcolsum = thiscolsum; thiscolsum = nextcolsum;
nuclear@2 383 }
nuclear@2 384
nuclear@2 385 /* Special case for last column */
nuclear@2 386 *outptr++ = (JSAMPLE) ((thiscolsum * 3 + lastcolsum + 8) >> 4);
nuclear@2 387 *outptr++ = (JSAMPLE) ((thiscolsum * 4 + 7) >> 4);
nuclear@2 388 }
nuclear@2 389 inrow++;
nuclear@2 390 }
nuclear@2 391 }
nuclear@2 392
nuclear@2 393
nuclear@2 394 /*
nuclear@2 395 * Module initialization routine for upsampling.
nuclear@2 396 */
nuclear@2 397
nuclear@2 398 GLOBAL(void)
nuclear@2 399 jinit_upsampler (j_decompress_ptr cinfo)
nuclear@2 400 {
nuclear@2 401 my_upsample_ptr upsample;
nuclear@2 402 int ci;
nuclear@2 403 jpeg_component_info * compptr;
nuclear@2 404 boolean need_buffer, do_fancy;
nuclear@2 405 int h_in_group, v_in_group, h_out_group, v_out_group;
nuclear@2 406
nuclear@2 407 upsample = (my_upsample_ptr)
nuclear@2 408 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
nuclear@2 409 SIZEOF(my_upsampler));
nuclear@2 410 cinfo->upsample = (struct jpeg_upsampler *) upsample;
nuclear@2 411 upsample->pub.start_pass = start_pass_upsample;
nuclear@2 412 upsample->pub.upsample = sep_upsample;
nuclear@2 413 upsample->pub.need_context_rows = FALSE; /* until we find out differently */
nuclear@2 414
nuclear@2 415 if (cinfo->CCIR601_sampling) /* this isn't supported */
nuclear@2 416 ERREXIT(cinfo, JERR_CCIR601_NOTIMPL);
nuclear@2 417
nuclear@2 418 /* jdmainct.c doesn't support context rows when min_DCT_scaled_size = 1,
nuclear@2 419 * so don't ask for it.
nuclear@2 420 */
nuclear@2 421 do_fancy = cinfo->do_fancy_upsampling && cinfo->min_DCT_scaled_size > 1;
nuclear@2 422
nuclear@2 423 /* Verify we can handle the sampling factors, select per-component methods,
nuclear@2 424 * and create storage as needed.
nuclear@2 425 */
nuclear@2 426 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
nuclear@2 427 ci++, compptr++) {
nuclear@2 428 /* Compute size of an "input group" after IDCT scaling. This many samples
nuclear@2 429 * are to be converted to max_h_samp_factor * max_v_samp_factor pixels.
nuclear@2 430 */
nuclear@2 431 h_in_group = (compptr->h_samp_factor * compptr->DCT_scaled_size) /
nuclear@2 432 cinfo->min_DCT_scaled_size;
nuclear@2 433 v_in_group = (compptr->v_samp_factor * compptr->DCT_scaled_size) /
nuclear@2 434 cinfo->min_DCT_scaled_size;
nuclear@2 435 h_out_group = cinfo->max_h_samp_factor;
nuclear@2 436 v_out_group = cinfo->max_v_samp_factor;
nuclear@2 437 upsample->rowgroup_height[ci] = v_in_group; /* save for use later */
nuclear@2 438 need_buffer = TRUE;
nuclear@2 439 if (! compptr->component_needed) {
nuclear@2 440 /* Don't bother to upsample an uninteresting component. */
nuclear@2 441 upsample->methods[ci] = noop_upsample;
nuclear@2 442 need_buffer = FALSE;
nuclear@2 443 } else if (h_in_group == h_out_group && v_in_group == v_out_group) {
nuclear@2 444 /* Fullsize components can be processed without any work. */
nuclear@2 445 upsample->methods[ci] = fullsize_upsample;
nuclear@2 446 need_buffer = FALSE;
nuclear@2 447 } else if (h_in_group * 2 == h_out_group &&
nuclear@2 448 v_in_group == v_out_group) {
nuclear@2 449 /* Special cases for 2h1v upsampling */
nuclear@2 450 if (do_fancy && compptr->downsampled_width > 2)
nuclear@2 451 upsample->methods[ci] = h2v1_fancy_upsample;
nuclear@2 452 else
nuclear@2 453 upsample->methods[ci] = h2v1_upsample;
nuclear@2 454 } else if (h_in_group * 2 == h_out_group &&
nuclear@2 455 v_in_group * 2 == v_out_group) {
nuclear@2 456 /* Special cases for 2h2v upsampling */
nuclear@2 457 if (do_fancy && compptr->downsampled_width > 2) {
nuclear@2 458 upsample->methods[ci] = h2v2_fancy_upsample;
nuclear@2 459 upsample->pub.need_context_rows = TRUE;
nuclear@2 460 } else
nuclear@2 461 upsample->methods[ci] = h2v2_upsample;
nuclear@2 462 } else if ((h_out_group % h_in_group) == 0 &&
nuclear@2 463 (v_out_group % v_in_group) == 0) {
nuclear@2 464 /* Generic integral-factors upsampling method */
nuclear@2 465 upsample->methods[ci] = int_upsample;
nuclear@2 466 upsample->h_expand[ci] = (UINT8) (h_out_group / h_in_group);
nuclear@2 467 upsample->v_expand[ci] = (UINT8) (v_out_group / v_in_group);
nuclear@2 468 } else
nuclear@2 469 ERREXIT(cinfo, JERR_FRACT_SAMPLE_NOTIMPL);
nuclear@2 470 if (need_buffer) {
nuclear@2 471 upsample->color_buf[ci] = (*cinfo->mem->alloc_sarray)
nuclear@2 472 ((j_common_ptr) cinfo, JPOOL_IMAGE,
nuclear@2 473 (JDIMENSION) jround_up((long) cinfo->output_width,
nuclear@2 474 (long) cinfo->max_h_samp_factor),
nuclear@2 475 (JDIMENSION) cinfo->max_v_samp_factor);
nuclear@2 476 }
nuclear@2 477 }
nuclear@2 478 }