Doxygen Source Code Documentation
jdmaster.c File Reference
#include "jinclude.h"
#include "jpeglib.h"
Go to the source code of this file.
Data Structures | |
struct | my_decomp_master |
Defines | |
#define | JPEG_INTERNALS |
Typedefs | |
typedef my_decomp_master * | my_master_ptr |
Functions | |
use_merged_upsample (j_decompress_ptr cinfo) | |
jpeg_calc_output_dimensions (j_decompress_ptr cinfo) | |
prepare_range_limit_table (j_decompress_ptr cinfo) | |
master_selection (j_decompress_ptr cinfo) | |
prepare_for_output_pass (j_decompress_ptr cinfo) | |
finish_output_pass (j_decompress_ptr cinfo) | |
jpeg_new_colormap (j_decompress_ptr cinfo) | |
jinit_master_decompress (j_decompress_ptr cinfo) |
Define Documentation
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Definition at line 14 of file jdmaster.c. |
Typedef Documentation
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Definition at line 35 of file jdmaster.c. |
Function Documentation
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Definition at line 498 of file jdmaster.c. References jpeg_decompress_struct::cquantize, jpeg_decompress_struct::master, my_decomp_master::pass_number, and jpeg_decompress_struct::quantize_colors. Referenced by jinit_master_decompress().
00499 { 00500 my_master_ptr master = (my_master_ptr) cinfo->master; 00501 00502 if (cinfo->quantize_colors) 00503 (*cinfo->cquantize->finish_pass) (cinfo); 00504 master->pass_number++; 00505 } |
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Definition at line 543 of file jdmaster.c. References finish_output_pass(), jpeg_decomp_master::is_dummy_pass, JPOOL_IMAGE, master_selection(), prepare_for_output_pass(), and SIZEOF. Referenced by jpeg_start_decompress().
00544 { 00545 my_master_ptr master; 00546 00547 master = (my_master_ptr) 00548 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, 00549 SIZEOF(my_decomp_master)); 00550 cinfo->master = (struct jpeg_decomp_master *) master; 00551 master->pub.prepare_for_output_pass = prepare_for_output_pass; 00552 master->pub.finish_output_pass = finish_output_pass; 00553 00554 master->pub.is_dummy_pass = FALSE; 00555 00556 master_selection(cinfo); 00557 } |
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Definition at line 84 of file jdmaster.c. References jpeg_decompress_struct::comp_info, compptr, jpeg_component_info::DCT_scaled_size, jpeg_component_info::downsampled_height, jpeg_component_info::downsampled_width, DSTATE_READY, ERREXIT1, jpeg_component_info::h_samp_factor, jpeg_decompress_struct::image_height, jpeg_decompress_struct::image_width, JCS_CMYK, JCS_GRAYSCALE, JCS_RGB, JCS_YCbCr, JCS_YCCK, jdiv_round_up(), L, jpeg_decompress_struct::max_h_samp_factor, jpeg_decompress_struct::max_v_samp_factor, jpeg_decompress_struct::min_DCT_scaled_size, jpeg_decompress_struct::num_components, jpeg_decompress_struct::out_color_components, jpeg_decompress_struct::out_color_space, jpeg_decompress_struct::output_components, jpeg_decompress_struct::output_height, jpeg_decompress_struct::output_width, jpeg_decompress_struct::quantize_colors, jpeg_decompress_struct::rec_outbuf_height, jpeg_decompress_struct::scale_denom, jpeg_decompress_struct::scale_num, use_merged_upsample(), and jpeg_component_info::v_samp_factor. Referenced by master_selection().
00086 { 00087 #ifdef IDCT_SCALING_SUPPORTED 00088 int ci; 00089 jpeg_component_info *compptr; 00090 #endif 00091 00092 /* Prevent application from calling me at wrong times */ 00093 if (cinfo->global_state != DSTATE_READY) 00094 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state); 00095 00096 #ifdef IDCT_SCALING_SUPPORTED 00097 00098 /* Compute actual output image dimensions and DCT scaling choices. */ 00099 if (cinfo->scale_num * 8 <= cinfo->scale_denom) { 00100 /* Provide 1/8 scaling */ 00101 cinfo->output_width = (JDIMENSION) 00102 jdiv_round_up((long) cinfo->image_width, 8L); 00103 cinfo->output_height = (JDIMENSION) 00104 jdiv_round_up((long) cinfo->image_height, 8L); 00105 cinfo->min_DCT_scaled_size = 1; 00106 } else if (cinfo->scale_num * 4 <= cinfo->scale_denom) { 00107 /* Provide 1/4 scaling */ 00108 cinfo->output_width = (JDIMENSION) 00109 jdiv_round_up((long) cinfo->image_width, 4L); 00110 cinfo->output_height = (JDIMENSION) 00111 jdiv_round_up((long) cinfo->image_height, 4L); 00112 cinfo->min_DCT_scaled_size = 2; 00113 } else if (cinfo->scale_num * 2 <= cinfo->scale_denom) { 00114 /* Provide 1/2 scaling */ 00115 cinfo->output_width = (JDIMENSION) 00116 jdiv_round_up((long) cinfo->image_width, 2L); 00117 cinfo->output_height = (JDIMENSION) 00118 jdiv_round_up((long) cinfo->image_height, 2L); 00119 cinfo->min_DCT_scaled_size = 4; 00120 } else { 00121 /* Provide 1/1 scaling */ 00122 cinfo->output_width = cinfo->image_width; 00123 cinfo->output_height = cinfo->image_height; 00124 cinfo->min_DCT_scaled_size = DCTSIZE; 00125 } 00126 /* In selecting the actual DCT scaling for each component, we try to 00127 * scale up the chroma components via IDCT scaling rather than upsampling. 00128 * This saves time if the upsampler gets to use 1:1 scaling. 00129 * Note this code assumes that the supported DCT scalings are powers of 2. 00130 */ 00131 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; 00132 ci++, compptr++) { 00133 int ssize = cinfo->min_DCT_scaled_size; 00134 while (ssize < DCTSIZE && 00135 (compptr->h_samp_factor * ssize * 2 <= 00136 cinfo->max_h_samp_factor * cinfo->min_DCT_scaled_size) && 00137 (compptr->v_samp_factor * ssize * 2 <= 00138 cinfo->max_v_samp_factor * cinfo->min_DCT_scaled_size)) { 00139 ssize = ssize * 2; 00140 } 00141 compptr->DCT_scaled_size = ssize; 00142 } 00143 00144 /* Recompute downsampled dimensions of components; 00145 * application needs to know these if using raw downsampled data. 00146 */ 00147 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; 00148 ci++, compptr++) { 00149 /* Size in samples, after IDCT scaling */ 00150 compptr->downsampled_width = (JDIMENSION) 00151 jdiv_round_up((long) cinfo->image_width * 00152 (long) (compptr->h_samp_factor * compptr->DCT_scaled_size), 00153 (long) (cinfo->max_h_samp_factor * DCTSIZE)); 00154 compptr->downsampled_height = (JDIMENSION) 00155 jdiv_round_up((long) cinfo->image_height * 00156 (long) (compptr->v_samp_factor * compptr->DCT_scaled_size), 00157 (long) (cinfo->max_v_samp_factor * DCTSIZE)); 00158 } 00159 00160 #else /* !IDCT_SCALING_SUPPORTED */ 00161 00162 /* Hardwire it to "no scaling" */ 00163 cinfo->output_width = cinfo->image_width; 00164 cinfo->output_height = cinfo->image_height; 00165 /* jdinput.c has already initialized DCT_scaled_size to DCTSIZE, 00166 * and has computed unscaled downsampled_width and downsampled_height. 00167 */ 00168 00169 #endif /* IDCT_SCALING_SUPPORTED */ 00170 00171 /* Report number of components in selected colorspace. */ 00172 /* Probably this should be in the color conversion module... */ 00173 switch (cinfo->out_color_space) { 00174 case JCS_GRAYSCALE: 00175 cinfo->out_color_components = 1; 00176 break; 00177 case JCS_RGB: 00178 #if RGB_PIXELSIZE != 3 00179 cinfo->out_color_components = RGB_PIXELSIZE; 00180 break; 00181 #endif /* else share code with YCbCr */ 00182 case JCS_YCbCr: 00183 cinfo->out_color_components = 3; 00184 break; 00185 case JCS_CMYK: 00186 case JCS_YCCK: 00187 cinfo->out_color_components = 4; 00188 break; 00189 default: /* else must be same colorspace as in file */ 00190 cinfo->out_color_components = cinfo->num_components; 00191 break; 00192 } 00193 cinfo->output_components = (cinfo->quantize_colors ? 1 : 00194 cinfo->out_color_components); 00195 00196 /* See if upsampler will want to emit more than one row at a time */ 00197 if (use_merged_upsample(cinfo)) 00198 cinfo->rec_outbuf_height = cinfo->max_v_samp_factor; 00199 else 00200 cinfo->rec_outbuf_height = 1; 00201 } |
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Definition at line 515 of file jdmaster.c. References jpeg_decompress_struct::colormap, jpeg_decompress_struct::cquantize, DSTATE_BUFIMAGE, jpeg_decompress_struct::enable_external_quant, ERREXIT, ERREXIT1, jpeg_decomp_master::is_dummy_pass, jpeg_decompress_struct::master, my_decomp_master::pub, jpeg_decompress_struct::quantize_colors, and my_decomp_master::quantizer_2pass.
00516 { 00517 my_master_ptr master = (my_master_ptr) cinfo->master; 00518 00519 /* Prevent application from calling me at wrong times */ 00520 if (cinfo->global_state != DSTATE_BUFIMAGE) 00521 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state); 00522 00523 if (cinfo->quantize_colors && cinfo->enable_external_quant && 00524 cinfo->colormap != NULL) { 00525 /* Select 2-pass quantizer for external colormap use */ 00526 cinfo->cquantize = master->quantizer_2pass; 00527 /* Notify quantizer of colormap change */ 00528 (*cinfo->cquantize->new_color_map) (cinfo); 00529 master->pub.is_dummy_pass = FALSE; /* just in case */ 00530 } else 00531 ERREXIT(cinfo, JERR_MODE_CHANGE); 00532 } |
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Definition at line 288 of file jdmaster.c. References jpeg_decompress_struct::arith_code, jpeg_decompress_struct::buffered_image, jpeg_decompress_struct::colormap, jpeg_decompress_struct::cquantize, jpeg_decompress_struct::enable_1pass_quant, jpeg_decompress_struct::enable_2pass_quant, jpeg_decompress_struct::enable_external_quant, ERREXIT, jpeg_input_controller::has_multiple_scans, jpeg_decompress_struct::inputctl, JDIMENSION, JERR_ARITH_NOTIMPL, jinit_1pass_quantizer(), jinit_2pass_quantizer(), jinit_color_deconverter(), jinit_d_coef_controller(), jinit_d_main_controller(), jinit_d_post_controller(), jinit_huff_decoder(), jinit_inverse_dct(), jinit_merged_upsampler(), jinit_phuff_decoder(), jinit_upsampler(), jpeg_calc_output_dimensions(), L, jpeg_decompress_struct::master, jpeg_decompress_struct::num_components, jpeg_decompress_struct::out_color_components, jpeg_decompress_struct::output_width, my_decomp_master::pass_number, prepare_range_limit_table(), jpeg_decompress_struct::progressive_mode, jpeg_decompress_struct::quantize_colors, my_decomp_master::quantizer_1pass, my_decomp_master::quantizer_2pass, jpeg_decompress_struct::raw_data_out, jpeg_decompress_struct::total_iMCU_rows, jpeg_decompress_struct::two_pass_quantize, use_merged_upsample(), and my_decomp_master::using_merged_upsample. Referenced by jinit_master_decompress().
00289 { 00290 my_master_ptr master = (my_master_ptr) cinfo->master; 00291 boolean use_c_buffer; 00292 long samplesperrow; 00293 JDIMENSION jd_samplesperrow; 00294 00295 /* Initialize dimensions and other stuff */ 00296 jpeg_calc_output_dimensions(cinfo); 00297 prepare_range_limit_table(cinfo); 00298 00299 /* Width of an output scanline must be representable as JDIMENSION. */ 00300 samplesperrow = (long) cinfo->output_width * (long) cinfo->out_color_components; 00301 jd_samplesperrow = (JDIMENSION) samplesperrow; 00302 if ((long) jd_samplesperrow != samplesperrow) 00303 ERREXIT(cinfo, JERR_WIDTH_OVERFLOW); 00304 00305 /* Initialize my private state */ 00306 master->pass_number = 0; 00307 master->using_merged_upsample = use_merged_upsample(cinfo); 00308 00309 /* Color quantizer selection */ 00310 master->quantizer_1pass = NULL; 00311 master->quantizer_2pass = NULL; 00312 /* No mode changes if not using buffered-image mode. */ 00313 if (! cinfo->quantize_colors || ! cinfo->buffered_image) { 00314 cinfo->enable_1pass_quant = FALSE; 00315 cinfo->enable_external_quant = FALSE; 00316 cinfo->enable_2pass_quant = FALSE; 00317 } 00318 if (cinfo->quantize_colors) { 00319 if (cinfo->raw_data_out) 00320 ERREXIT(cinfo, JERR_NOTIMPL); 00321 /* 2-pass quantizer only works in 3-component color space. */ 00322 if (cinfo->out_color_components != 3) { 00323 cinfo->enable_1pass_quant = TRUE; 00324 cinfo->enable_external_quant = FALSE; 00325 cinfo->enable_2pass_quant = FALSE; 00326 cinfo->colormap = NULL; 00327 } else if (cinfo->colormap != NULL) { 00328 cinfo->enable_external_quant = TRUE; 00329 } else if (cinfo->two_pass_quantize) { 00330 cinfo->enable_2pass_quant = TRUE; 00331 } else { 00332 cinfo->enable_1pass_quant = TRUE; 00333 } 00334 00335 if (cinfo->enable_1pass_quant) { 00336 #ifdef QUANT_1PASS_SUPPORTED 00337 jinit_1pass_quantizer(cinfo); 00338 master->quantizer_1pass = cinfo->cquantize; 00339 #else 00340 ERREXIT(cinfo, JERR_NOT_COMPILED); 00341 #endif 00342 } 00343 00344 /* We use the 2-pass code to map to external colormaps. */ 00345 if (cinfo->enable_2pass_quant || cinfo->enable_external_quant) { 00346 #ifdef QUANT_2PASS_SUPPORTED 00347 jinit_2pass_quantizer(cinfo); 00348 master->quantizer_2pass = cinfo->cquantize; 00349 #else 00350 ERREXIT(cinfo, JERR_NOT_COMPILED); 00351 #endif 00352 } 00353 /* If both quantizers are initialized, the 2-pass one is left active; 00354 * this is necessary for starting with quantization to an external map. 00355 */ 00356 } 00357 00358 /* Post-processing: in particular, color conversion first */ 00359 if (! cinfo->raw_data_out) { 00360 if (master->using_merged_upsample) { 00361 #ifdef UPSAMPLE_MERGING_SUPPORTED 00362 jinit_merged_upsampler(cinfo); /* does color conversion too */ 00363 #else 00364 ERREXIT(cinfo, JERR_NOT_COMPILED); 00365 #endif 00366 } else { 00367 jinit_color_deconverter(cinfo); 00368 jinit_upsampler(cinfo); 00369 } 00370 jinit_d_post_controller(cinfo, cinfo->enable_2pass_quant); 00371 } 00372 /* Inverse DCT */ 00373 jinit_inverse_dct(cinfo); 00374 /* Entropy decoding: either Huffman or arithmetic coding. */ 00375 if (cinfo->arith_code) { 00376 ERREXIT(cinfo, JERR_ARITH_NOTIMPL); 00377 } else { 00378 if (cinfo->progressive_mode) { 00379 #ifdef D_PROGRESSIVE_SUPPORTED 00380 jinit_phuff_decoder(cinfo); 00381 #else 00382 ERREXIT(cinfo, JERR_NOT_COMPILED); 00383 #endif 00384 } else 00385 jinit_huff_decoder(cinfo); 00386 } 00387 00388 /* Initialize principal buffer controllers. */ 00389 use_c_buffer = cinfo->inputctl->has_multiple_scans || cinfo->buffered_image; 00390 jinit_d_coef_controller(cinfo, use_c_buffer); 00391 00392 if (! cinfo->raw_data_out) 00393 jinit_d_main_controller(cinfo, FALSE /* never need full buffer here */); 00394 00395 /* We can now tell the memory manager to allocate virtual arrays. */ 00396 (*cinfo->mem->realize_virt_arrays) ((j_common_ptr) cinfo); 00397 00398 /* Initialize input side of decompressor to consume first scan. */ 00399 (*cinfo->inputctl->start_input_pass) (cinfo); 00400 00401 #ifdef D_MULTISCAN_FILES_SUPPORTED 00402 /* If jpeg_start_decompress will read the whole file, initialize 00403 * progress monitoring appropriately. The input step is counted 00404 * as one pass. 00405 */ 00406 if (cinfo->progress != NULL && ! cinfo->buffered_image && 00407 cinfo->inputctl->has_multiple_scans) { 00408 int nscans; 00409 /* Estimate number of scans to set pass_limit. */ 00410 if (cinfo->progressive_mode) { 00411 /* Arbitrarily estimate 2 interleaved DC scans + 3 AC scans/component. */ 00412 nscans = 2 + 3 * cinfo->num_components; 00413 } else { 00414 /* For a nonprogressive multiscan file, estimate 1 scan per component. */ 00415 nscans = cinfo->num_components; 00416 } 00417 cinfo->progress->pass_counter = 0L; 00418 cinfo->progress->pass_limit = (long) cinfo->total_iMCU_rows * nscans; 00419 cinfo->progress->completed_passes = 0; 00420 cinfo->progress->total_passes = (cinfo->enable_2pass_quant ? 3 : 2); 00421 /* Count the input pass as done */ 00422 master->pass_number++; 00423 } 00424 #endif /* D_MULTISCAN_FILES_SUPPORTED */ 00425 } |
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Definition at line 438 of file jdmaster.c. References jpeg_decompress_struct::buffered_image, jpeg_decompress_struct::cconvert, jpeg_decompress_struct::coef, jpeg_decompress_struct::colormap, jpeg_decompress_struct::cquantize, jpeg_decompress_struct::enable_1pass_quant, jpeg_decompress_struct::enable_2pass_quant, jpeg_input_controller::eoi_reached, ERREXIT, jpeg_decompress_struct::idct, jpeg_decompress_struct::inputctl, jpeg_decomp_master::is_dummy_pass, JBUF_CRANK_DEST, JBUF_PASS_THRU, JBUF_SAVE_AND_PASS, jpeg_decompress_struct::main, jpeg_decompress_struct::master, my_decomp_master::pass_number, jpeg_decompress_struct::post, my_decomp_master::pub, jpeg_decompress_struct::quantize_colors, my_decomp_master::quantizer_1pass, my_decomp_master::quantizer_2pass, jpeg_decompress_struct::raw_data_out, jpeg_decompress_struct::two_pass_quantize, jpeg_decompress_struct::upsample, and my_decomp_master::using_merged_upsample. Referenced by jinit_master_decompress().
00439 { 00440 my_master_ptr master = (my_master_ptr) cinfo->master; 00441 00442 if (master->pub.is_dummy_pass) { 00443 #ifdef QUANT_2PASS_SUPPORTED 00444 /* Final pass of 2-pass quantization */ 00445 master->pub.is_dummy_pass = FALSE; 00446 (*cinfo->cquantize->start_pass) (cinfo, FALSE); 00447 (*cinfo->post->start_pass) (cinfo, JBUF_CRANK_DEST); 00448 (*cinfo->main->start_pass) (cinfo, JBUF_CRANK_DEST); 00449 #else 00450 ERREXIT(cinfo, JERR_NOT_COMPILED); 00451 #endif /* QUANT_2PASS_SUPPORTED */ 00452 } else { 00453 if (cinfo->quantize_colors && cinfo->colormap == NULL) { 00454 /* Select new quantization method */ 00455 if (cinfo->two_pass_quantize && cinfo->enable_2pass_quant) { 00456 cinfo->cquantize = master->quantizer_2pass; 00457 master->pub.is_dummy_pass = TRUE; 00458 } else if (cinfo->enable_1pass_quant) { 00459 cinfo->cquantize = master->quantizer_1pass; 00460 } else { 00461 ERREXIT(cinfo, JERR_MODE_CHANGE); 00462 } 00463 } 00464 (*cinfo->idct->start_pass) (cinfo); 00465 (*cinfo->coef->start_output_pass) (cinfo); 00466 if (! cinfo->raw_data_out) { 00467 if (! master->using_merged_upsample) 00468 (*cinfo->cconvert->start_pass) (cinfo); 00469 (*cinfo->upsample->start_pass) (cinfo); 00470 if (cinfo->quantize_colors) 00471 (*cinfo->cquantize->start_pass) (cinfo, master->pub.is_dummy_pass); 00472 (*cinfo->post->start_pass) (cinfo, 00473 (master->pub.is_dummy_pass ? JBUF_SAVE_AND_PASS : JBUF_PASS_THRU)); 00474 (*cinfo->main->start_pass) (cinfo, JBUF_PASS_THRU); 00475 } 00476 } 00477 00478 /* Set up progress monitor's pass info if present */ 00479 if (cinfo->progress != NULL) { 00480 cinfo->progress->completed_passes = master->pass_number; 00481 cinfo->progress->total_passes = master->pass_number + 00482 (master->pub.is_dummy_pass ? 2 : 1); 00483 /* In buffered-image mode, we assume one more output pass if EOI not 00484 * yet reached, but no more passes if EOI has been reached. 00485 */ 00486 if (cinfo->buffered_image && ! cinfo->inputctl->eoi_reached) { 00487 cinfo->progress->total_passes += (cinfo->enable_2pass_quant ? 2 : 1); 00488 } 00489 } 00490 } |
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Definition at line 248 of file jdmaster.c. References CENTERJSAMPLE, i, JPOOL_IMAGE, JSAMPLE, MAXJSAMPLE, MEMCOPY, MEMZERO, and SIZEOF. Referenced by master_selection().
00250 { 00251 JSAMPLE * table; 00252 int i; 00253 00254 table = (JSAMPLE *) 00255 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, 00256 (5 * (MAXJSAMPLE+1) + CENTERJSAMPLE) * SIZEOF(JSAMPLE)); 00257 table += (MAXJSAMPLE+1); /* allow negative subscripts of simple table */ 00258 cinfo->sample_range_limit = table; 00259 /* First segment of "simple" table: limit[x] = 0 for x < 0 */ 00260 MEMZERO(table - (MAXJSAMPLE+1), (MAXJSAMPLE+1) * SIZEOF(JSAMPLE)); 00261 /* Main part of "simple" table: limit[x] = x */ 00262 for (i = 0; i <= MAXJSAMPLE; i++) 00263 table[i] = (JSAMPLE) i; 00264 table += CENTERJSAMPLE; /* Point to where post-IDCT table starts */ 00265 /* End of simple table, rest of first half of post-IDCT table */ 00266 for (i = CENTERJSAMPLE; i < 2*(MAXJSAMPLE+1); i++) 00267 table[i] = MAXJSAMPLE; 00268 /* Second half of post-IDCT table */ 00269 MEMZERO(table + (2 * (MAXJSAMPLE+1)), 00270 (2 * (MAXJSAMPLE+1) - CENTERJSAMPLE) * SIZEOF(JSAMPLE)); 00271 MEMCOPY(table + (4 * (MAXJSAMPLE+1) - CENTERJSAMPLE), 00272 cinfo->sample_range_limit, CENTERJSAMPLE * SIZEOF(JSAMPLE)); 00273 } |
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Definition at line 44 of file jdmaster.c. References jpeg_decompress_struct::CCIR601_sampling, jpeg_decompress_struct::comp_info, jpeg_component_info::DCT_scaled_size, jpeg_decompress_struct::do_fancy_upsampling, jpeg_component_info::h_samp_factor, JCS_RGB, JCS_YCbCr, jpeg_decompress_struct::jpeg_color_space, jpeg_decompress_struct::min_DCT_scaled_size, jpeg_decompress_struct::num_components, jpeg_decompress_struct::out_color_components, jpeg_decompress_struct::out_color_space, and jpeg_component_info::v_samp_factor. Referenced by jpeg_calc_output_dimensions(), and master_selection().
00045 { 00046 #ifdef UPSAMPLE_MERGING_SUPPORTED 00047 /* Merging is the equivalent of plain box-filter upsampling */ 00048 if (cinfo->do_fancy_upsampling || cinfo->CCIR601_sampling) 00049 return FALSE; 00050 /* jdmerge.c only supports YCC=>RGB color conversion */ 00051 if (cinfo->jpeg_color_space != JCS_YCbCr || cinfo->num_components != 3 || 00052 cinfo->out_color_space != JCS_RGB || 00053 cinfo->out_color_components != RGB_PIXELSIZE) 00054 return FALSE; 00055 /* and it only handles 2h1v or 2h2v sampling ratios */ 00056 if (cinfo->comp_info[0].h_samp_factor != 2 || 00057 cinfo->comp_info[1].h_samp_factor != 1 || 00058 cinfo->comp_info[2].h_samp_factor != 1 || 00059 cinfo->comp_info[0].v_samp_factor > 2 || 00060 cinfo->comp_info[1].v_samp_factor != 1 || 00061 cinfo->comp_info[2].v_samp_factor != 1) 00062 return FALSE; 00063 /* furthermore, it doesn't work if we've scaled the IDCTs differently */ 00064 if (cinfo->comp_info[0].DCT_scaled_size != cinfo->min_DCT_scaled_size || 00065 cinfo->comp_info[1].DCT_scaled_size != cinfo->min_DCT_scaled_size || 00066 cinfo->comp_info[2].DCT_scaled_size != cinfo->min_DCT_scaled_size) 00067 return FALSE; 00068 /* ??? also need to test for upsample-time rescaling, when & if supported */ 00069 return TRUE; /* by golly, it'll work... */ 00070 #else 00071 return FALSE; 00072 #endif 00073 } |