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annotate libs/libjpeg/jdsample.c @ 26:862a3329a8f0

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wohooo, added a shitload of code from zlib/libpng/libjpeg. When the good lord was raining shared libraries the iphone held a fucking umbrella...
author John Tsiombikas <nuclear@mutantstargoat.com>
date Thu, 08 Sep 2011 06:28:38 +0300
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nuclear@26 1 /*
nuclear@26 2 * jdsample.c
nuclear@26 3 *
nuclear@26 4 * Copyright (C) 1991-1996, Thomas G. Lane.
nuclear@26 5 * This file is part of the Independent JPEG Group's software.
nuclear@26 6 * For conditions of distribution and use, see the accompanying README file.
nuclear@26 7 *
nuclear@26 8 * This file contains upsampling routines.
nuclear@26 9 *
nuclear@26 10 * Upsampling input data is counted in "row groups". A row group
nuclear@26 11 * is defined to be (v_samp_factor * DCT_scaled_size / min_DCT_scaled_size)
nuclear@26 12 * sample rows of each component. Upsampling will normally produce
nuclear@26 13 * max_v_samp_factor pixel rows from each row group (but this could vary
nuclear@26 14 * if the upsampler is applying a scale factor of its own).
nuclear@26 15 *
nuclear@26 16 * An excellent reference for image resampling is
nuclear@26 17 * Digital Image Warping, George Wolberg, 1990.
nuclear@26 18 * Pub. by IEEE Computer Society Press, Los Alamitos, CA. ISBN 0-8186-8944-7.
nuclear@26 19 */
nuclear@26 20
nuclear@26 21 #define JPEG_INTERNALS
nuclear@26 22 #include "jinclude.h"
nuclear@26 23 #include "jpeglib.h"
nuclear@26 24
nuclear@26 25
nuclear@26 26 /* Pointer to routine to upsample a single component */
nuclear@26 27 typedef JMETHOD(void, upsample1_ptr,
nuclear@26 28 (j_decompress_ptr cinfo, jpeg_component_info * compptr,
nuclear@26 29 JSAMPARRAY input_data, JSAMPARRAY * output_data_ptr));
nuclear@26 30
nuclear@26 31 /* Private subobject */
nuclear@26 32
nuclear@26 33 typedef struct {
nuclear@26 34 struct jpeg_upsampler pub; /* public fields */
nuclear@26 35
nuclear@26 36 /* Color conversion buffer. When using separate upsampling and color
nuclear@26 37 * conversion steps, this buffer holds one upsampled row group until it
nuclear@26 38 * has been color converted and output.
nuclear@26 39 * Note: we do not allocate any storage for component(s) which are full-size,
nuclear@26 40 * ie do not need rescaling. The corresponding entry of color_buf[] is
nuclear@26 41 * simply set to point to the input data array, thereby avoiding copying.
nuclear@26 42 */
nuclear@26 43 JSAMPARRAY color_buf[MAX_COMPONENTS];
nuclear@26 44
nuclear@26 45 /* Per-component upsampling method pointers */
nuclear@26 46 upsample1_ptr methods[MAX_COMPONENTS];
nuclear@26 47
nuclear@26 48 int next_row_out; /* counts rows emitted from color_buf */
nuclear@26 49 JDIMENSION rows_to_go; /* counts rows remaining in image */
nuclear@26 50
nuclear@26 51 /* Height of an input row group for each component. */
nuclear@26 52 int rowgroup_height[MAX_COMPONENTS];
nuclear@26 53
nuclear@26 54 /* These arrays save pixel expansion factors so that int_expand need not
nuclear@26 55 * recompute them each time. They are unused for other upsampling methods.
nuclear@26 56 */
nuclear@26 57 UINT8 h_expand[MAX_COMPONENTS];
nuclear@26 58 UINT8 v_expand[MAX_COMPONENTS];
nuclear@26 59 } my_upsampler;
nuclear@26 60
nuclear@26 61 typedef my_upsampler * my_upsample_ptr;
nuclear@26 62
nuclear@26 63
nuclear@26 64 /*
nuclear@26 65 * Initialize for an upsampling pass.
nuclear@26 66 */
nuclear@26 67
nuclear@26 68 METHODDEF(void)
nuclear@26 69 start_pass_upsample (j_decompress_ptr cinfo)
nuclear@26 70 {
nuclear@26 71 my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample;
nuclear@26 72
nuclear@26 73 /* Mark the conversion buffer empty */
nuclear@26 74 upsample->next_row_out = cinfo->max_v_samp_factor;
nuclear@26 75 /* Initialize total-height counter for detecting bottom of image */
nuclear@26 76 upsample->rows_to_go = cinfo->output_height;
nuclear@26 77 }
nuclear@26 78
nuclear@26 79
nuclear@26 80 /*
nuclear@26 81 * Control routine to do upsampling (and color conversion).
nuclear@26 82 *
nuclear@26 83 * In this version we upsample each component independently.
nuclear@26 84 * We upsample one row group into the conversion buffer, then apply
nuclear@26 85 * color conversion a row at a time.
nuclear@26 86 */
nuclear@26 87
nuclear@26 88 METHODDEF(void)
nuclear@26 89 sep_upsample (j_decompress_ptr cinfo,
nuclear@26 90 JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr,
nuclear@26 91 JDIMENSION in_row_groups_avail,
nuclear@26 92 JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,
nuclear@26 93 JDIMENSION out_rows_avail)
nuclear@26 94 {
nuclear@26 95 my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample;
nuclear@26 96 int ci;
nuclear@26 97 jpeg_component_info * compptr;
nuclear@26 98 JDIMENSION num_rows;
nuclear@26 99
nuclear@26 100 /* Fill the conversion buffer, if it's empty */
nuclear@26 101 if (upsample->next_row_out >= cinfo->max_v_samp_factor) {
nuclear@26 102 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
nuclear@26 103 ci++, compptr++) {
nuclear@26 104 /* Invoke per-component upsample method. Notice we pass a POINTER
nuclear@26 105 * to color_buf[ci], so that fullsize_upsample can change it.
nuclear@26 106 */
nuclear@26 107 (*upsample->methods[ci]) (cinfo, compptr,
nuclear@26 108 input_buf[ci] + (*in_row_group_ctr * upsample->rowgroup_height[ci]),
nuclear@26 109 upsample->color_buf + ci);
nuclear@26 110 }
nuclear@26 111 upsample->next_row_out = 0;
nuclear@26 112 }
nuclear@26 113
nuclear@26 114 /* Color-convert and emit rows */
nuclear@26 115
nuclear@26 116 /* How many we have in the buffer: */
nuclear@26 117 num_rows = (JDIMENSION) (cinfo->max_v_samp_factor - upsample->next_row_out);
nuclear@26 118 /* Not more than the distance to the end of the image. Need this test
nuclear@26 119 * in case the image height is not a multiple of max_v_samp_factor:
nuclear@26 120 */
nuclear@26 121 if (num_rows > upsample->rows_to_go)
nuclear@26 122 num_rows = upsample->rows_to_go;
nuclear@26 123 /* And not more than what the client can accept: */
nuclear@26 124 out_rows_avail -= *out_row_ctr;
nuclear@26 125 if (num_rows > out_rows_avail)
nuclear@26 126 num_rows = out_rows_avail;
nuclear@26 127
nuclear@26 128 (*cinfo->cconvert->color_convert) (cinfo, upsample->color_buf,
nuclear@26 129 (JDIMENSION) upsample->next_row_out,
nuclear@26 130 output_buf + *out_row_ctr,
nuclear@26 131 (int) num_rows);
nuclear@26 132
nuclear@26 133 /* Adjust counts */
nuclear@26 134 *out_row_ctr += num_rows;
nuclear@26 135 upsample->rows_to_go -= num_rows;
nuclear@26 136 upsample->next_row_out += num_rows;
nuclear@26 137 /* When the buffer is emptied, declare this input row group consumed */
nuclear@26 138 if (upsample->next_row_out >= cinfo->max_v_samp_factor)
nuclear@26 139 (*in_row_group_ctr)++;
nuclear@26 140 }
nuclear@26 141
nuclear@26 142
nuclear@26 143 /*
nuclear@26 144 * These are the routines invoked by sep_upsample to upsample pixel values
nuclear@26 145 * of a single component. One row group is processed per call.
nuclear@26 146 */
nuclear@26 147
nuclear@26 148
nuclear@26 149 /*
nuclear@26 150 * For full-size components, we just make color_buf[ci] point at the
nuclear@26 151 * input buffer, and thus avoid copying any data. Note that this is
nuclear@26 152 * safe only because sep_upsample doesn't declare the input row group
nuclear@26 153 * "consumed" until we are done color converting and emitting it.
nuclear@26 154 */
nuclear@26 155
nuclear@26 156 METHODDEF(void)
nuclear@26 157 fullsize_upsample (j_decompress_ptr cinfo, jpeg_component_info * compptr,
nuclear@26 158 JSAMPARRAY input_data, JSAMPARRAY * output_data_ptr)
nuclear@26 159 {
nuclear@26 160 *output_data_ptr = input_data;
nuclear@26 161 }
nuclear@26 162
nuclear@26 163
nuclear@26 164 /*
nuclear@26 165 * This is a no-op version used for "uninteresting" components.
nuclear@26 166 * These components will not be referenced by color conversion.
nuclear@26 167 */
nuclear@26 168
nuclear@26 169 METHODDEF(void)
nuclear@26 170 noop_upsample (j_decompress_ptr cinfo, jpeg_component_info * compptr,
nuclear@26 171 JSAMPARRAY input_data, JSAMPARRAY * output_data_ptr)
nuclear@26 172 {
nuclear@26 173 *output_data_ptr = NULL; /* safety check */
nuclear@26 174 }
nuclear@26 175
nuclear@26 176
nuclear@26 177 /*
nuclear@26 178 * This version handles any integral sampling ratios.
nuclear@26 179 * This is not used for typical JPEG files, so it need not be fast.
nuclear@26 180 * Nor, for that matter, is it particularly accurate: the algorithm is
nuclear@26 181 * simple replication of the input pixel onto the corresponding output
nuclear@26 182 * pixels. The hi-falutin sampling literature refers to this as a
nuclear@26 183 * "box filter". A box filter tends to introduce visible artifacts,
nuclear@26 184 * so if you are actually going to use 3:1 or 4:1 sampling ratios
nuclear@26 185 * you would be well advised to improve this code.
nuclear@26 186 */
nuclear@26 187
nuclear@26 188 METHODDEF(void)
nuclear@26 189 int_upsample (j_decompress_ptr cinfo, jpeg_component_info * compptr,
nuclear@26 190 JSAMPARRAY input_data, JSAMPARRAY * output_data_ptr)
nuclear@26 191 {
nuclear@26 192 my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample;
nuclear@26 193 JSAMPARRAY output_data = *output_data_ptr;
nuclear@26 194 register JSAMPROW inptr, outptr;
nuclear@26 195 register JSAMPLE invalue;
nuclear@26 196 register int h;
nuclear@26 197 JSAMPROW outend;
nuclear@26 198 int h_expand, v_expand;
nuclear@26 199 int inrow, outrow;
nuclear@26 200
nuclear@26 201 h_expand = upsample->h_expand[compptr->component_index];
nuclear@26 202 v_expand = upsample->v_expand[compptr->component_index];
nuclear@26 203
nuclear@26 204 inrow = outrow = 0;
nuclear@26 205 while (outrow < cinfo->max_v_samp_factor) {
nuclear@26 206 /* Generate one output row with proper horizontal expansion */
nuclear@26 207 inptr = input_data[inrow];
nuclear@26 208 outptr = output_data[outrow];
nuclear@26 209 outend = outptr + cinfo->output_width;
nuclear@26 210 while (outptr < outend) {
nuclear@26 211 invalue = *inptr++; /* don't need GETJSAMPLE() here */
nuclear@26 212 for (h = h_expand; h > 0; h--) {
nuclear@26 213 *outptr++ = invalue;
nuclear@26 214 }
nuclear@26 215 }
nuclear@26 216 /* Generate any additional output rows by duplicating the first one */
nuclear@26 217 if (v_expand > 1) {
nuclear@26 218 jcopy_sample_rows(output_data, outrow, output_data, outrow+1,
nuclear@26 219 v_expand-1, cinfo->output_width);
nuclear@26 220 }
nuclear@26 221 inrow++;
nuclear@26 222 outrow += v_expand;
nuclear@26 223 }
nuclear@26 224 }
nuclear@26 225
nuclear@26 226
nuclear@26 227 /*
nuclear@26 228 * Fast processing for the common case of 2:1 horizontal and 1:1 vertical.
nuclear@26 229 * It's still a box filter.
nuclear@26 230 */
nuclear@26 231
nuclear@26 232 METHODDEF(void)
nuclear@26 233 h2v1_upsample (j_decompress_ptr cinfo, jpeg_component_info * compptr,
nuclear@26 234 JSAMPARRAY input_data, JSAMPARRAY * output_data_ptr)
nuclear@26 235 {
nuclear@26 236 JSAMPARRAY output_data = *output_data_ptr;
nuclear@26 237 register JSAMPROW inptr, outptr;
nuclear@26 238 register JSAMPLE invalue;
nuclear@26 239 JSAMPROW outend;
nuclear@26 240 int inrow;
nuclear@26 241
nuclear@26 242 for (inrow = 0; inrow < cinfo->max_v_samp_factor; inrow++) {
nuclear@26 243 inptr = input_data[inrow];
nuclear@26 244 outptr = output_data[inrow];
nuclear@26 245 outend = outptr + cinfo->output_width;
nuclear@26 246 while (outptr < outend) {
nuclear@26 247 invalue = *inptr++; /* don't need GETJSAMPLE() here */
nuclear@26 248 *outptr++ = invalue;
nuclear@26 249 *outptr++ = invalue;
nuclear@26 250 }
nuclear@26 251 }
nuclear@26 252 }
nuclear@26 253
nuclear@26 254
nuclear@26 255 /*
nuclear@26 256 * Fast processing for the common case of 2:1 horizontal and 2:1 vertical.
nuclear@26 257 * It's still a box filter.
nuclear@26 258 */
nuclear@26 259
nuclear@26 260 METHODDEF(void)
nuclear@26 261 h2v2_upsample (j_decompress_ptr cinfo, jpeg_component_info * compptr,
nuclear@26 262 JSAMPARRAY input_data, JSAMPARRAY * output_data_ptr)
nuclear@26 263 {
nuclear@26 264 JSAMPARRAY output_data = *output_data_ptr;
nuclear@26 265 register JSAMPROW inptr, outptr;
nuclear@26 266 register JSAMPLE invalue;
nuclear@26 267 JSAMPROW outend;
nuclear@26 268 int inrow, outrow;
nuclear@26 269
nuclear@26 270 inrow = outrow = 0;
nuclear@26 271 while (outrow < cinfo->max_v_samp_factor) {
nuclear@26 272 inptr = input_data[inrow];
nuclear@26 273 outptr = output_data[outrow];
nuclear@26 274 outend = outptr + cinfo->output_width;
nuclear@26 275 while (outptr < outend) {
nuclear@26 276 invalue = *inptr++; /* don't need GETJSAMPLE() here */
nuclear@26 277 *outptr++ = invalue;
nuclear@26 278 *outptr++ = invalue;
nuclear@26 279 }
nuclear@26 280 jcopy_sample_rows(output_data, outrow, output_data, outrow+1,
nuclear@26 281 1, cinfo->output_width);
nuclear@26 282 inrow++;
nuclear@26 283 outrow += 2;
nuclear@26 284 }
nuclear@26 285 }
nuclear@26 286
nuclear@26 287
nuclear@26 288 /*
nuclear@26 289 * Fancy processing for the common case of 2:1 horizontal and 1:1 vertical.
nuclear@26 290 *
nuclear@26 291 * The upsampling algorithm is linear interpolation between pixel centers,
nuclear@26 292 * also known as a "triangle filter". This is a good compromise between
nuclear@26 293 * speed and visual quality. The centers of the output pixels are 1/4 and 3/4
nuclear@26 294 * of the way between input pixel centers.
nuclear@26 295 *
nuclear@26 296 * A note about the "bias" calculations: when rounding fractional values to
nuclear@26 297 * integer, we do not want to always round 0.5 up to the next integer.
nuclear@26 298 * If we did that, we'd introduce a noticeable bias towards larger values.
nuclear@26 299 * Instead, this code is arranged so that 0.5 will be rounded up or down at
nuclear@26 300 * alternate pixel locations (a simple ordered dither pattern).
nuclear@26 301 */
nuclear@26 302
nuclear@26 303 METHODDEF(void)
nuclear@26 304 h2v1_fancy_upsample (j_decompress_ptr cinfo, jpeg_component_info * compptr,
nuclear@26 305 JSAMPARRAY input_data, JSAMPARRAY * output_data_ptr)
nuclear@26 306 {
nuclear@26 307 JSAMPARRAY output_data = *output_data_ptr;
nuclear@26 308 register JSAMPROW inptr, outptr;
nuclear@26 309 register int invalue;
nuclear@26 310 register JDIMENSION colctr;
nuclear@26 311 int inrow;
nuclear@26 312
nuclear@26 313 for (inrow = 0; inrow < cinfo->max_v_samp_factor; inrow++) {
nuclear@26 314 inptr = input_data[inrow];
nuclear@26 315 outptr = output_data[inrow];
nuclear@26 316 /* Special case for first column */
nuclear@26 317 invalue = GETJSAMPLE(*inptr++);
nuclear@26 318 *outptr++ = (JSAMPLE) invalue;
nuclear@26 319 *outptr++ = (JSAMPLE) ((invalue * 3 + GETJSAMPLE(*inptr) + 2) >> 2);
nuclear@26 320
nuclear@26 321 for (colctr = compptr->downsampled_width - 2; colctr > 0; colctr--) {
nuclear@26 322 /* General case: 3/4 * nearer pixel + 1/4 * further pixel */
nuclear@26 323 invalue = GETJSAMPLE(*inptr++) * 3;
nuclear@26 324 *outptr++ = (JSAMPLE) ((invalue + GETJSAMPLE(inptr[-2]) + 1) >> 2);
nuclear@26 325 *outptr++ = (JSAMPLE) ((invalue + GETJSAMPLE(*inptr) + 2) >> 2);
nuclear@26 326 }
nuclear@26 327
nuclear@26 328 /* Special case for last column */
nuclear@26 329 invalue = GETJSAMPLE(*inptr);
nuclear@26 330 *outptr++ = (JSAMPLE) ((invalue * 3 + GETJSAMPLE(inptr[-1]) + 1) >> 2);
nuclear@26 331 *outptr++ = (JSAMPLE) invalue;
nuclear@26 332 }
nuclear@26 333 }
nuclear@26 334
nuclear@26 335
nuclear@26 336 /*
nuclear@26 337 * Fancy processing for the common case of 2:1 horizontal and 2:1 vertical.
nuclear@26 338 * Again a triangle filter; see comments for h2v1 case, above.
nuclear@26 339 *
nuclear@26 340 * It is OK for us to reference the adjacent input rows because we demanded
nuclear@26 341 * context from the main buffer controller (see initialization code).
nuclear@26 342 */
nuclear@26 343
nuclear@26 344 METHODDEF(void)
nuclear@26 345 h2v2_fancy_upsample (j_decompress_ptr cinfo, jpeg_component_info * compptr,
nuclear@26 346 JSAMPARRAY input_data, JSAMPARRAY * output_data_ptr)
nuclear@26 347 {
nuclear@26 348 JSAMPARRAY output_data = *output_data_ptr;
nuclear@26 349 register JSAMPROW inptr0, inptr1, outptr;
nuclear@26 350 #if BITS_IN_JSAMPLE == 8
nuclear@26 351 register int thiscolsum, lastcolsum, nextcolsum;
nuclear@26 352 #else
nuclear@26 353 register INT32 thiscolsum, lastcolsum, nextcolsum;
nuclear@26 354 #endif
nuclear@26 355 register JDIMENSION colctr;
nuclear@26 356 int inrow, outrow, v;
nuclear@26 357
nuclear@26 358 inrow = outrow = 0;
nuclear@26 359 while (outrow < cinfo->max_v_samp_factor) {
nuclear@26 360 for (v = 0; v < 2; v++) {
nuclear@26 361 /* inptr0 points to nearest input row, inptr1 points to next nearest */
nuclear@26 362 inptr0 = input_data[inrow];
nuclear@26 363 if (v == 0) /* next nearest is row above */
nuclear@26 364 inptr1 = input_data[inrow-1];
nuclear@26 365 else /* next nearest is row below */
nuclear@26 366 inptr1 = input_data[inrow+1];
nuclear@26 367 outptr = output_data[outrow++];
nuclear@26 368
nuclear@26 369 /* Special case for first column */
nuclear@26 370 thiscolsum = GETJSAMPLE(*inptr0++) * 3 + GETJSAMPLE(*inptr1++);
nuclear@26 371 nextcolsum = GETJSAMPLE(*inptr0++) * 3 + GETJSAMPLE(*inptr1++);
nuclear@26 372 *outptr++ = (JSAMPLE) ((thiscolsum * 4 + 8) >> 4);
nuclear@26 373 *outptr++ = (JSAMPLE) ((thiscolsum * 3 + nextcolsum + 7) >> 4);
nuclear@26 374 lastcolsum = thiscolsum; thiscolsum = nextcolsum;
nuclear@26 375
nuclear@26 376 for (colctr = compptr->downsampled_width - 2; colctr > 0; colctr--) {
nuclear@26 377 /* General case: 3/4 * nearer pixel + 1/4 * further pixel in each */
nuclear@26 378 /* dimension, thus 9/16, 3/16, 3/16, 1/16 overall */
nuclear@26 379 nextcolsum = GETJSAMPLE(*inptr0++) * 3 + GETJSAMPLE(*inptr1++);
nuclear@26 380 *outptr++ = (JSAMPLE) ((thiscolsum * 3 + lastcolsum + 8) >> 4);
nuclear@26 381 *outptr++ = (JSAMPLE) ((thiscolsum * 3 + nextcolsum + 7) >> 4);
nuclear@26 382 lastcolsum = thiscolsum; thiscolsum = nextcolsum;
nuclear@26 383 }
nuclear@26 384
nuclear@26 385 /* Special case for last column */
nuclear@26 386 *outptr++ = (JSAMPLE) ((thiscolsum * 3 + lastcolsum + 8) >> 4);
nuclear@26 387 *outptr++ = (JSAMPLE) ((thiscolsum * 4 + 7) >> 4);
nuclear@26 388 }
nuclear@26 389 inrow++;
nuclear@26 390 }
nuclear@26 391 }
nuclear@26 392
nuclear@26 393
nuclear@26 394 /*
nuclear@26 395 * Module initialization routine for upsampling.
nuclear@26 396 */
nuclear@26 397
nuclear@26 398 GLOBAL(void)
nuclear@26 399 jinit_upsampler (j_decompress_ptr cinfo)
nuclear@26 400 {
nuclear@26 401 my_upsample_ptr upsample;
nuclear@26 402 int ci;
nuclear@26 403 jpeg_component_info * compptr;
nuclear@26 404 boolean need_buffer, do_fancy;
nuclear@26 405 int h_in_group, v_in_group, h_out_group, v_out_group;
nuclear@26 406
nuclear@26 407 upsample = (my_upsample_ptr)
nuclear@26 408 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
nuclear@26 409 SIZEOF(my_upsampler));
nuclear@26 410 cinfo->upsample = (struct jpeg_upsampler *) upsample;
nuclear@26 411 upsample->pub.start_pass = start_pass_upsample;
nuclear@26 412 upsample->pub.upsample = sep_upsample;
nuclear@26 413 upsample->pub.need_context_rows = FALSE; /* until we find out differently */
nuclear@26 414
nuclear@26 415 if (cinfo->CCIR601_sampling) /* this isn't supported */
nuclear@26 416 ERREXIT(cinfo, JERR_CCIR601_NOTIMPL);
nuclear@26 417
nuclear@26 418 /* jdmainct.c doesn't support context rows when min_DCT_scaled_size = 1,
nuclear@26 419 * so don't ask for it.
nuclear@26 420 */
nuclear@26 421 do_fancy = cinfo->do_fancy_upsampling && cinfo->min_DCT_scaled_size > 1;
nuclear@26 422
nuclear@26 423 /* Verify we can handle the sampling factors, select per-component methods,
nuclear@26 424 * and create storage as needed.
nuclear@26 425 */
nuclear@26 426 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
nuclear@26 427 ci++, compptr++) {
nuclear@26 428 /* Compute size of an "input group" after IDCT scaling. This many samples
nuclear@26 429 * are to be converted to max_h_samp_factor * max_v_samp_factor pixels.
nuclear@26 430 */
nuclear@26 431 h_in_group = (compptr->h_samp_factor * compptr->DCT_scaled_size) /
nuclear@26 432 cinfo->min_DCT_scaled_size;
nuclear@26 433 v_in_group = (compptr->v_samp_factor * compptr->DCT_scaled_size) /
nuclear@26 434 cinfo->min_DCT_scaled_size;
nuclear@26 435 h_out_group = cinfo->max_h_samp_factor;
nuclear@26 436 v_out_group = cinfo->max_v_samp_factor;
nuclear@26 437 upsample->rowgroup_height[ci] = v_in_group; /* save for use later */
nuclear@26 438 need_buffer = TRUE;
nuclear@26 439 if (! compptr->component_needed) {
nuclear@26 440 /* Don't bother to upsample an uninteresting component. */
nuclear@26 441 upsample->methods[ci] = noop_upsample;
nuclear@26 442 need_buffer = FALSE;
nuclear@26 443 } else if (h_in_group == h_out_group && v_in_group == v_out_group) {
nuclear@26 444 /* Fullsize components can be processed without any work. */
nuclear@26 445 upsample->methods[ci] = fullsize_upsample;
nuclear@26 446 need_buffer = FALSE;
nuclear@26 447 } else if (h_in_group * 2 == h_out_group &&
nuclear@26 448 v_in_group == v_out_group) {
nuclear@26 449 /* Special cases for 2h1v upsampling */
nuclear@26 450 if (do_fancy && compptr->downsampled_width > 2)
nuclear@26 451 upsample->methods[ci] = h2v1_fancy_upsample;
nuclear@26 452 else
nuclear@26 453 upsample->methods[ci] = h2v1_upsample;
nuclear@26 454 } else if (h_in_group * 2 == h_out_group &&
nuclear@26 455 v_in_group * 2 == v_out_group) {
nuclear@26 456 /* Special cases for 2h2v upsampling */
nuclear@26 457 if (do_fancy && compptr->downsampled_width > 2) {
nuclear@26 458 upsample->methods[ci] = h2v2_fancy_upsample;
nuclear@26 459 upsample->pub.need_context_rows = TRUE;
nuclear@26 460 } else
nuclear@26 461 upsample->methods[ci] = h2v2_upsample;
nuclear@26 462 } else if ((h_out_group % h_in_group) == 0 &&
nuclear@26 463 (v_out_group % v_in_group) == 0) {
nuclear@26 464 /* Generic integral-factors upsampling method */
nuclear@26 465 upsample->methods[ci] = int_upsample;
nuclear@26 466 upsample->h_expand[ci] = (UINT8) (h_out_group / h_in_group);
nuclear@26 467 upsample->v_expand[ci] = (UINT8) (v_out_group / v_in_group);
nuclear@26 468 } else
nuclear@26 469 ERREXIT(cinfo, JERR_FRACT_SAMPLE_NOTIMPL);
nuclear@26 470 if (need_buffer) {
nuclear@26 471 upsample->color_buf[ci] = (*cinfo->mem->alloc_sarray)
nuclear@26 472 ((j_common_ptr) cinfo, JPOOL_IMAGE,
nuclear@26 473 (JDIMENSION) jround_up((long) cinfo->output_width,
nuclear@26 474 (long) cinfo->max_h_samp_factor),
nuclear@26 475 (JDIMENSION) cinfo->max_v_samp_factor);
nuclear@26 476 }
nuclear@26 477 }
nuclear@26 478 }