jcparam.c 23 KB

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  1. /*
  2. * jcparam.c
  3. *
  4. * Copyright (C) 1991-1998, Thomas G. Lane.
  5. * Modified 2003-2013 by Guido Vollbeding.
  6. * This file is part of the Independent JPEG Group's software.
  7. * For conditions of distribution and use, see the accompanying README file.
  8. *
  9. * This file contains optional default-setting code for the JPEG compressor.
  10. * Applications do not have to use this file, but those that don't use it
  11. * must know a lot more about the innards of the JPEG code.
  12. */
  13. #define JPEG_INTERNALS
  14. #include "jinclude.h"
  15. #include "jpeglib.h"
  16. /*
  17. * Quantization table setup routines
  18. */
  19. GLOBAL(void)
  20. jpeg_add_quant_table (j_compress_ptr cinfo, int which_tbl,
  21. const unsigned int *basic_table,
  22. int scale_factor, boolean force_baseline)
  23. /* Define a quantization table equal to the basic_table times
  24. * a scale factor (given as a percentage).
  25. * If force_baseline is TRUE, the computed quantization table entries
  26. * are limited to 1..255 for JPEG baseline compatibility.
  27. */
  28. {
  29. JQUANT_TBL ** qtblptr;
  30. int i;
  31. long temp;
  32. /* Safety check to ensure start_compress not called yet. */
  33. if (cinfo->global_state != CSTATE_START)
  34. ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
  35. if (which_tbl < 0 || which_tbl >= NUM_QUANT_TBLS)
  36. ERREXIT1(cinfo, JERR_DQT_INDEX, which_tbl);
  37. qtblptr = & cinfo->quant_tbl_ptrs[which_tbl];
  38. if (*qtblptr == NULL)
  39. *qtblptr = jpeg_alloc_quant_table((j_common_ptr) cinfo);
  40. for (i = 0; i < DCTSIZE2; i++) {
  41. temp = ((long) basic_table[i] * scale_factor + 50L) / 100L;
  42. /* limit the values to the valid range */
  43. if (temp <= 0L) temp = 1L;
  44. if (temp > 32767L) temp = 32767L; /* max quantizer needed for 12 bits */
  45. if (force_baseline && temp > 255L)
  46. temp = 255L; /* limit to baseline range if requested */
  47. (*qtblptr)->quantval[i] = (UINT16) temp;
  48. }
  49. /* Initialize sent_table FALSE so table will be written to JPEG file. */
  50. (*qtblptr)->sent_table = FALSE;
  51. }
  52. /* These are the sample quantization tables given in JPEG spec section K.1.
  53. * The spec says that the values given produce "good" quality, and
  54. * when divided by 2, "very good" quality.
  55. */
  56. static const unsigned int std_luminance_quant_tbl[DCTSIZE2] = {
  57. 16, 11, 10, 16, 24, 40, 51, 61,
  58. 12, 12, 14, 19, 26, 58, 60, 55,
  59. 14, 13, 16, 24, 40, 57, 69, 56,
  60. 14, 17, 22, 29, 51, 87, 80, 62,
  61. 18, 22, 37, 56, 68, 109, 103, 77,
  62. 24, 35, 55, 64, 81, 104, 113, 92,
  63. 49, 64, 78, 87, 103, 121, 120, 101,
  64. 72, 92, 95, 98, 112, 100, 103, 99
  65. };
  66. static const unsigned int std_chrominance_quant_tbl[DCTSIZE2] = {
  67. 17, 18, 24, 47, 99, 99, 99, 99,
  68. 18, 21, 26, 66, 99, 99, 99, 99,
  69. 24, 26, 56, 99, 99, 99, 99, 99,
  70. 47, 66, 99, 99, 99, 99, 99, 99,
  71. 99, 99, 99, 99, 99, 99, 99, 99,
  72. 99, 99, 99, 99, 99, 99, 99, 99,
  73. 99, 99, 99, 99, 99, 99, 99, 99,
  74. 99, 99, 99, 99, 99, 99, 99, 99
  75. };
  76. GLOBAL(void)
  77. jpeg_default_qtables (j_compress_ptr cinfo, boolean force_baseline)
  78. /* Set or change the 'quality' (quantization) setting, using default tables
  79. * and straight percentage-scaling quality scales.
  80. * This entry point allows different scalings for luminance and chrominance.
  81. */
  82. {
  83. /* Set up two quantization tables using the specified scaling */
  84. jpeg_add_quant_table(cinfo, 0, std_luminance_quant_tbl,
  85. cinfo->q_scale_factor[0], force_baseline);
  86. jpeg_add_quant_table(cinfo, 1, std_chrominance_quant_tbl,
  87. cinfo->q_scale_factor[1], force_baseline);
  88. }
  89. GLOBAL(void)
  90. jpeg_set_linear_quality (j_compress_ptr cinfo, int scale_factor,
  91. boolean force_baseline)
  92. /* Set or change the 'quality' (quantization) setting, using default tables
  93. * and a straight percentage-scaling quality scale. In most cases it's better
  94. * to use jpeg_set_quality (below); this entry point is provided for
  95. * applications that insist on a linear percentage scaling.
  96. */
  97. {
  98. /* Set up two quantization tables using the specified scaling */
  99. jpeg_add_quant_table(cinfo, 0, std_luminance_quant_tbl,
  100. scale_factor, force_baseline);
  101. jpeg_add_quant_table(cinfo, 1, std_chrominance_quant_tbl,
  102. scale_factor, force_baseline);
  103. }
  104. GLOBAL(int)
  105. jpeg_quality_scaling (int quality)
  106. /* Convert a user-specified quality rating to a percentage scaling factor
  107. * for an underlying quantization table, using our recommended scaling curve.
  108. * The input 'quality' factor should be 0 (terrible) to 100 (very good).
  109. */
  110. {
  111. /* Safety limit on quality factor. Convert 0 to 1 to avoid zero divide. */
  112. if (quality <= 0) quality = 1;
  113. if (quality > 100) quality = 100;
  114. /* The basic table is used as-is (scaling 100) for a quality of 50.
  115. * Qualities 50..100 are converted to scaling percentage 200 - 2*Q;
  116. * note that at Q=100 the scaling is 0, which will cause jpeg_add_quant_table
  117. * to make all the table entries 1 (hence, minimum quantization loss).
  118. * Qualities 1..50 are converted to scaling percentage 5000/Q.
  119. */
  120. if (quality < 50)
  121. quality = 5000 / quality;
  122. else
  123. quality = 200 - quality*2;
  124. return quality;
  125. }
  126. GLOBAL(void)
  127. jpeg_set_quality (j_compress_ptr cinfo, int quality, boolean force_baseline)
  128. /* Set or change the 'quality' (quantization) setting, using default tables.
  129. * This is the standard quality-adjusting entry point for typical user
  130. * interfaces; only those who want detailed control over quantization tables
  131. * would use the preceding routines directly.
  132. */
  133. {
  134. /* Convert user 0-100 rating to percentage scaling */
  135. quality = jpeg_quality_scaling(quality);
  136. /* Set up standard quality tables */
  137. jpeg_set_linear_quality(cinfo, quality, force_baseline);
  138. }
  139. /*
  140. * Huffman table setup routines
  141. */
  142. LOCAL(void)
  143. add_huff_table (j_compress_ptr cinfo,
  144. JHUFF_TBL **htblptr, const UINT8 *bits, const UINT8 *val)
  145. /* Define a Huffman table */
  146. {
  147. int nsymbols, len;
  148. if (*htblptr == NULL)
  149. *htblptr = jpeg_alloc_huff_table((j_common_ptr) cinfo);
  150. /* Copy the number-of-symbols-of-each-code-length counts */
  151. MEMCOPY((*htblptr)->bits, bits, SIZEOF((*htblptr)->bits));
  152. /* Validate the counts. We do this here mainly so we can copy the right
  153. * number of symbols from the val[] array, without risking marching off
  154. * the end of memory. jchuff.c will do a more thorough test later.
  155. */
  156. nsymbols = 0;
  157. for (len = 1; len <= 16; len++)
  158. nsymbols += bits[len];
  159. if (nsymbols < 1 || nsymbols > 256)
  160. ERREXIT(cinfo, JERR_BAD_HUFF_TABLE);
  161. MEMCOPY((*htblptr)->huffval, val, nsymbols * SIZEOF(UINT8));
  162. /* Initialize sent_table FALSE so table will be written to JPEG file. */
  163. (*htblptr)->sent_table = FALSE;
  164. }
  165. LOCAL(void)
  166. std_huff_tables (j_compress_ptr cinfo)
  167. /* Set up the standard Huffman tables (cf. JPEG standard section K.3) */
  168. /* IMPORTANT: these are only valid for 8-bit data precision! */
  169. {
  170. static const UINT8 bits_dc_luminance[17] =
  171. { /* 0-base */ 0, 0, 1, 5, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0 };
  172. static const UINT8 val_dc_luminance[] =
  173. { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 };
  174. static const UINT8 bits_dc_chrominance[17] =
  175. { /* 0-base */ 0, 0, 3, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0 };
  176. static const UINT8 val_dc_chrominance[] =
  177. { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 };
  178. static const UINT8 bits_ac_luminance[17] =
  179. { /* 0-base */ 0, 0, 2, 1, 3, 3, 2, 4, 3, 5, 5, 4, 4, 0, 0, 1, 0x7d };
  180. static const UINT8 val_ac_luminance[] =
  181. { 0x01, 0x02, 0x03, 0x00, 0x04, 0x11, 0x05, 0x12,
  182. 0x21, 0x31, 0x41, 0x06, 0x13, 0x51, 0x61, 0x07,
  183. 0x22, 0x71, 0x14, 0x32, 0x81, 0x91, 0xa1, 0x08,
  184. 0x23, 0x42, 0xb1, 0xc1, 0x15, 0x52, 0xd1, 0xf0,
  185. 0x24, 0x33, 0x62, 0x72, 0x82, 0x09, 0x0a, 0x16,
  186. 0x17, 0x18, 0x19, 0x1a, 0x25, 0x26, 0x27, 0x28,
  187. 0x29, 0x2a, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39,
  188. 0x3a, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48, 0x49,
  189. 0x4a, 0x53, 0x54, 0x55, 0x56, 0x57, 0x58, 0x59,
  190. 0x5a, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68, 0x69,
  191. 0x6a, 0x73, 0x74, 0x75, 0x76, 0x77, 0x78, 0x79,
  192. 0x7a, 0x83, 0x84, 0x85, 0x86, 0x87, 0x88, 0x89,
  193. 0x8a, 0x92, 0x93, 0x94, 0x95, 0x96, 0x97, 0x98,
  194. 0x99, 0x9a, 0xa2, 0xa3, 0xa4, 0xa5, 0xa6, 0xa7,
  195. 0xa8, 0xa9, 0xaa, 0xb2, 0xb3, 0xb4, 0xb5, 0xb6,
  196. 0xb7, 0xb8, 0xb9, 0xba, 0xc2, 0xc3, 0xc4, 0xc5,
  197. 0xc6, 0xc7, 0xc8, 0xc9, 0xca, 0xd2, 0xd3, 0xd4,
  198. 0xd5, 0xd6, 0xd7, 0xd8, 0xd9, 0xda, 0xe1, 0xe2,
  199. 0xe3, 0xe4, 0xe5, 0xe6, 0xe7, 0xe8, 0xe9, 0xea,
  200. 0xf1, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7, 0xf8,
  201. 0xf9, 0xfa };
  202. static const UINT8 bits_ac_chrominance[17] =
  203. { /* 0-base */ 0, 0, 2, 1, 2, 4, 4, 3, 4, 7, 5, 4, 4, 0, 1, 2, 0x77 };
  204. static const UINT8 val_ac_chrominance[] =
  205. { 0x00, 0x01, 0x02, 0x03, 0x11, 0x04, 0x05, 0x21,
  206. 0x31, 0x06, 0x12, 0x41, 0x51, 0x07, 0x61, 0x71,
  207. 0x13, 0x22, 0x32, 0x81, 0x08, 0x14, 0x42, 0x91,
  208. 0xa1, 0xb1, 0xc1, 0x09, 0x23, 0x33, 0x52, 0xf0,
  209. 0x15, 0x62, 0x72, 0xd1, 0x0a, 0x16, 0x24, 0x34,
  210. 0xe1, 0x25, 0xf1, 0x17, 0x18, 0x19, 0x1a, 0x26,
  211. 0x27, 0x28, 0x29, 0x2a, 0x35, 0x36, 0x37, 0x38,
  212. 0x39, 0x3a, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48,
  213. 0x49, 0x4a, 0x53, 0x54, 0x55, 0x56, 0x57, 0x58,
  214. 0x59, 0x5a, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68,
  215. 0x69, 0x6a, 0x73, 0x74, 0x75, 0x76, 0x77, 0x78,
  216. 0x79, 0x7a, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87,
  217. 0x88, 0x89, 0x8a, 0x92, 0x93, 0x94, 0x95, 0x96,
  218. 0x97, 0x98, 0x99, 0x9a, 0xa2, 0xa3, 0xa4, 0xa5,
  219. 0xa6, 0xa7, 0xa8, 0xa9, 0xaa, 0xb2, 0xb3, 0xb4,
  220. 0xb5, 0xb6, 0xb7, 0xb8, 0xb9, 0xba, 0xc2, 0xc3,
  221. 0xc4, 0xc5, 0xc6, 0xc7, 0xc8, 0xc9, 0xca, 0xd2,
  222. 0xd3, 0xd4, 0xd5, 0xd6, 0xd7, 0xd8, 0xd9, 0xda,
  223. 0xe2, 0xe3, 0xe4, 0xe5, 0xe6, 0xe7, 0xe8, 0xe9,
  224. 0xea, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7, 0xf8,
  225. 0xf9, 0xfa };
  226. add_huff_table(cinfo, &cinfo->dc_huff_tbl_ptrs[0],
  227. bits_dc_luminance, val_dc_luminance);
  228. add_huff_table(cinfo, &cinfo->ac_huff_tbl_ptrs[0],
  229. bits_ac_luminance, val_ac_luminance);
  230. add_huff_table(cinfo, &cinfo->dc_huff_tbl_ptrs[1],
  231. bits_dc_chrominance, val_dc_chrominance);
  232. add_huff_table(cinfo, &cinfo->ac_huff_tbl_ptrs[1],
  233. bits_ac_chrominance, val_ac_chrominance);
  234. }
  235. /*
  236. * Default parameter setup for compression.
  237. *
  238. * Applications that don't choose to use this routine must do their
  239. * own setup of all these parameters. Alternately, you can call this
  240. * to establish defaults and then alter parameters selectively. This
  241. * is the recommended approach since, if we add any new parameters,
  242. * your code will still work (they'll be set to reasonable defaults).
  243. */
  244. GLOBAL(void)
  245. jpeg_set_defaults (j_compress_ptr cinfo)
  246. {
  247. int i;
  248. /* Safety check to ensure start_compress not called yet. */
  249. if (cinfo->global_state != CSTATE_START)
  250. ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
  251. /* Allocate comp_info array large enough for maximum component count.
  252. * Array is made permanent in case application wants to compress
  253. * multiple images at same param settings.
  254. */
  255. if (cinfo->comp_info == NULL)
  256. cinfo->comp_info = (jpeg_component_info *)
  257. (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT,
  258. MAX_COMPONENTS * SIZEOF(jpeg_component_info));
  259. /* Initialize everything not dependent on the color space */
  260. cinfo->scale_num = 1; /* 1:1 scaling */
  261. cinfo->scale_denom = 1;
  262. cinfo->data_precision = BITS_IN_JSAMPLE;
  263. /* Set up two quantization tables using default quality of 75 */
  264. jpeg_set_quality(cinfo, 75, TRUE);
  265. /* Set up two Huffman tables */
  266. std_huff_tables(cinfo);
  267. /* Initialize default arithmetic coding conditioning */
  268. for (i = 0; i < NUM_ARITH_TBLS; i++) {
  269. cinfo->arith_dc_L[i] = 0;
  270. cinfo->arith_dc_U[i] = 1;
  271. cinfo->arith_ac_K[i] = 5;
  272. }
  273. /* Default is no multiple-scan output */
  274. cinfo->scan_info = NULL;
  275. cinfo->num_scans = 0;
  276. /* Expect normal source image, not raw downsampled data */
  277. cinfo->raw_data_in = FALSE;
  278. /* The standard Huffman tables are only valid for 8-bit data precision.
  279. * If the precision is higher, use arithmetic coding.
  280. * (Alternatively, using Huffman coding would be possible with forcing
  281. * optimization on so that usable tables will be computed, or by
  282. * supplying default tables that are valid for the desired precision.)
  283. * Otherwise, use Huffman coding by default.
  284. */
  285. cinfo->arith_code = cinfo->data_precision > 8 ? TRUE : FALSE;
  286. /* By default, don't do extra passes to optimize entropy coding */
  287. cinfo->optimize_coding = FALSE;
  288. /* By default, use the simpler non-cosited sampling alignment */
  289. cinfo->CCIR601_sampling = FALSE;
  290. /* By default, apply fancy downsampling */
  291. cinfo->do_fancy_downsampling = TRUE;
  292. /* No input smoothing */
  293. cinfo->smoothing_factor = 0;
  294. /* DCT algorithm preference */
  295. cinfo->dct_method = JDCT_DEFAULT;
  296. /* No restart markers */
  297. cinfo->restart_interval = 0;
  298. cinfo->restart_in_rows = 0;
  299. /* Fill in default JFIF marker parameters. Note that whether the marker
  300. * will actually be written is determined by jpeg_set_colorspace.
  301. *
  302. * By default, the library emits JFIF version code 1.01.
  303. * An application that wants to emit JFIF 1.02 extension markers should set
  304. * JFIF_minor_version to 2. We could probably get away with just defaulting
  305. * to 1.02, but there may still be some decoders in use that will complain
  306. * about that; saying 1.01 should minimize compatibility problems.
  307. *
  308. * For wide gamut colorspaces (BG_RGB and BG_YCC), the major version will be
  309. * overridden by jpeg_set_colorspace and set to 2.
  310. */
  311. cinfo->JFIF_major_version = 1; /* Default JFIF version = 1.01 */
  312. cinfo->JFIF_minor_version = 1;
  313. cinfo->density_unit = 0; /* Pixel size is unknown by default */
  314. cinfo->X_density = 1; /* Pixel aspect ratio is square by default */
  315. cinfo->Y_density = 1;
  316. /* No color transform */
  317. cinfo->color_transform = JCT_NONE;
  318. /* Choose JPEG colorspace based on input space, set defaults accordingly */
  319. jpeg_default_colorspace(cinfo);
  320. }
  321. /*
  322. * Select an appropriate JPEG colorspace for in_color_space.
  323. */
  324. GLOBAL(void)
  325. jpeg_default_colorspace (j_compress_ptr cinfo)
  326. {
  327. switch (cinfo->in_color_space) {
  328. case JCS_UNKNOWN:
  329. jpeg_set_colorspace(cinfo, JCS_UNKNOWN);
  330. break;
  331. case JCS_GRAYSCALE:
  332. jpeg_set_colorspace(cinfo, JCS_GRAYSCALE);
  333. break;
  334. case JCS_RGB:
  335. jpeg_set_colorspace(cinfo, JCS_YCbCr);
  336. break;
  337. case JCS_YCbCr:
  338. jpeg_set_colorspace(cinfo, JCS_YCbCr);
  339. break;
  340. case JCS_CMYK:
  341. jpeg_set_colorspace(cinfo, JCS_CMYK); /* By default, no translation */
  342. break;
  343. case JCS_YCCK:
  344. jpeg_set_colorspace(cinfo, JCS_YCCK);
  345. break;
  346. case JCS_BG_RGB:
  347. /* No translation for now -- conversion to BG_YCC not yet supportet */
  348. jpeg_set_colorspace(cinfo, JCS_BG_RGB);
  349. break;
  350. case JCS_BG_YCC:
  351. jpeg_set_colorspace(cinfo, JCS_BG_YCC);
  352. break;
  353. default:
  354. ERREXIT(cinfo, JERR_BAD_IN_COLORSPACE);
  355. }
  356. }
  357. /*
  358. * Set the JPEG colorspace, and choose colorspace-dependent default values.
  359. */
  360. GLOBAL(void)
  361. jpeg_set_colorspace (j_compress_ptr cinfo, J_COLOR_SPACE colorspace)
  362. {
  363. jpeg_component_info * compptr;
  364. int ci;
  365. #define SET_COMP(index,id,hsamp,vsamp,quant,dctbl,actbl) \
  366. (compptr = &cinfo->comp_info[index], \
  367. compptr->component_id = (id), \
  368. compptr->h_samp_factor = (hsamp), \
  369. compptr->v_samp_factor = (vsamp), \
  370. compptr->quant_tbl_no = (quant), \
  371. compptr->dc_tbl_no = (dctbl), \
  372. compptr->ac_tbl_no = (actbl) )
  373. /* Safety check to ensure start_compress not called yet. */
  374. if (cinfo->global_state != CSTATE_START)
  375. ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
  376. /* For all colorspaces, we use Q and Huff tables 0 for luminance components,
  377. * tables 1 for chrominance components.
  378. */
  379. cinfo->jpeg_color_space = colorspace;
  380. cinfo->write_JFIF_header = FALSE; /* No marker for non-JFIF colorspaces */
  381. cinfo->write_Adobe_marker = FALSE; /* write no Adobe marker by default */
  382. switch (colorspace) {
  383. case JCS_UNKNOWN:
  384. cinfo->num_components = cinfo->input_components;
  385. if (cinfo->num_components < 1 || cinfo->num_components > MAX_COMPONENTS)
  386. ERREXIT2(cinfo, JERR_COMPONENT_COUNT, cinfo->num_components,
  387. MAX_COMPONENTS);
  388. for (ci = 0; ci < cinfo->num_components; ci++) {
  389. SET_COMP(ci, ci, 1,1, 0, 0,0);
  390. }
  391. break;
  392. case JCS_GRAYSCALE:
  393. cinfo->write_JFIF_header = TRUE; /* Write a JFIF marker */
  394. cinfo->num_components = 1;
  395. /* JFIF specifies component ID 1 */
  396. SET_COMP(0, 0x01, 1,1, 0, 0,0);
  397. break;
  398. case JCS_RGB:
  399. cinfo->write_Adobe_marker = TRUE; /* write Adobe marker to flag RGB */
  400. cinfo->num_components = 3;
  401. SET_COMP(0, 0x52 /* 'R' */, 1,1, 0,
  402. cinfo->color_transform == JCT_SUBTRACT_GREEN ? 1 : 0,
  403. cinfo->color_transform == JCT_SUBTRACT_GREEN ? 1 : 0);
  404. SET_COMP(1, 0x47 /* 'G' */, 1,1, 0, 0,0);
  405. SET_COMP(2, 0x42 /* 'B' */, 1,1, 0,
  406. cinfo->color_transform == JCT_SUBTRACT_GREEN ? 1 : 0,
  407. cinfo->color_transform == JCT_SUBTRACT_GREEN ? 1 : 0);
  408. break;
  409. case JCS_YCbCr:
  410. cinfo->write_JFIF_header = TRUE; /* Write a JFIF marker */
  411. cinfo->num_components = 3;
  412. /* JFIF specifies component IDs 1,2,3 */
  413. /* We default to 2x2 subsamples of chrominance */
  414. SET_COMP(0, 0x01, 2,2, 0, 0,0);
  415. SET_COMP(1, 0x02, 1,1, 1, 1,1);
  416. SET_COMP(2, 0x03, 1,1, 1, 1,1);
  417. break;
  418. case JCS_CMYK:
  419. cinfo->write_Adobe_marker = TRUE; /* write Adobe marker to flag CMYK */
  420. cinfo->num_components = 4;
  421. SET_COMP(0, 0x43 /* 'C' */, 1,1, 0, 0,0);
  422. SET_COMP(1, 0x4D /* 'M' */, 1,1, 0, 0,0);
  423. SET_COMP(2, 0x59 /* 'Y' */, 1,1, 0, 0,0);
  424. SET_COMP(3, 0x4B /* 'K' */, 1,1, 0, 0,0);
  425. break;
  426. case JCS_YCCK:
  427. cinfo->write_Adobe_marker = TRUE; /* write Adobe marker to flag YCCK */
  428. cinfo->num_components = 4;
  429. SET_COMP(0, 0x01, 2,2, 0, 0,0);
  430. SET_COMP(1, 0x02, 1,1, 1, 1,1);
  431. SET_COMP(2, 0x03, 1,1, 1, 1,1);
  432. SET_COMP(3, 0x04, 2,2, 0, 0,0);
  433. break;
  434. case JCS_BG_RGB:
  435. cinfo->write_JFIF_header = TRUE; /* Write a JFIF marker */
  436. cinfo->JFIF_major_version = 2; /* Set JFIF major version = 2 */
  437. cinfo->num_components = 3;
  438. /* Add offset 0x20 to the normal R/G/B component IDs */
  439. SET_COMP(0, 0x72 /* 'r' */, 1,1, 0,
  440. cinfo->color_transform == JCT_SUBTRACT_GREEN ? 1 : 0,
  441. cinfo->color_transform == JCT_SUBTRACT_GREEN ? 1 : 0);
  442. SET_COMP(1, 0x67 /* 'g' */, 1,1, 0, 0,0);
  443. SET_COMP(2, 0x62 /* 'b' */, 1,1, 0,
  444. cinfo->color_transform == JCT_SUBTRACT_GREEN ? 1 : 0,
  445. cinfo->color_transform == JCT_SUBTRACT_GREEN ? 1 : 0);
  446. break;
  447. case JCS_BG_YCC:
  448. cinfo->write_JFIF_header = TRUE; /* Write a JFIF marker */
  449. cinfo->JFIF_major_version = 2; /* Set JFIF major version = 2 */
  450. cinfo->num_components = 3;
  451. /* Add offset 0x20 to the normal Cb/Cr component IDs */
  452. /* We default to 2x2 subsamples of chrominance */
  453. SET_COMP(0, 0x01, 2,2, 0, 0,0);
  454. SET_COMP(1, 0x22, 1,1, 1, 1,1);
  455. SET_COMP(2, 0x23, 1,1, 1, 1,1);
  456. break;
  457. default:
  458. ERREXIT(cinfo, JERR_BAD_J_COLORSPACE);
  459. }
  460. }
  461. #ifdef C_PROGRESSIVE_SUPPORTED
  462. LOCAL(jpeg_scan_info *)
  463. fill_a_scan (jpeg_scan_info * scanptr, int ci,
  464. int Ss, int Se, int Ah, int Al)
  465. /* Support routine: generate one scan for specified component */
  466. {
  467. scanptr->comps_in_scan = 1;
  468. scanptr->component_index[0] = ci;
  469. scanptr->Ss = Ss;
  470. scanptr->Se = Se;
  471. scanptr->Ah = Ah;
  472. scanptr->Al = Al;
  473. scanptr++;
  474. return scanptr;
  475. }
  476. LOCAL(jpeg_scan_info *)
  477. fill_scans (jpeg_scan_info * scanptr, int ncomps,
  478. int Ss, int Se, int Ah, int Al)
  479. /* Support routine: generate one scan for each component */
  480. {
  481. int ci;
  482. for (ci = 0; ci < ncomps; ci++) {
  483. scanptr->comps_in_scan = 1;
  484. scanptr->component_index[0] = ci;
  485. scanptr->Ss = Ss;
  486. scanptr->Se = Se;
  487. scanptr->Ah = Ah;
  488. scanptr->Al = Al;
  489. scanptr++;
  490. }
  491. return scanptr;
  492. }
  493. LOCAL(jpeg_scan_info *)
  494. fill_dc_scans (jpeg_scan_info * scanptr, int ncomps, int Ah, int Al)
  495. /* Support routine: generate interleaved DC scan if possible, else N scans */
  496. {
  497. int ci;
  498. if (ncomps <= MAX_COMPS_IN_SCAN) {
  499. /* Single interleaved DC scan */
  500. scanptr->comps_in_scan = ncomps;
  501. for (ci = 0; ci < ncomps; ci++)
  502. scanptr->component_index[ci] = ci;
  503. scanptr->Ss = scanptr->Se = 0;
  504. scanptr->Ah = Ah;
  505. scanptr->Al = Al;
  506. scanptr++;
  507. } else {
  508. /* Noninterleaved DC scan for each component */
  509. scanptr = fill_scans(scanptr, ncomps, 0, 0, Ah, Al);
  510. }
  511. return scanptr;
  512. }
  513. /*
  514. * Create a recommended progressive-JPEG script.
  515. * cinfo->num_components and cinfo->jpeg_color_space must be correct.
  516. */
  517. GLOBAL(void)
  518. jpeg_simple_progression (j_compress_ptr cinfo)
  519. {
  520. int ncomps = cinfo->num_components;
  521. int nscans;
  522. jpeg_scan_info * scanptr;
  523. /* Safety check to ensure start_compress not called yet. */
  524. if (cinfo->global_state != CSTATE_START)
  525. ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
  526. /* Figure space needed for script. Calculation must match code below! */
  527. if (ncomps == 3 &&
  528. (cinfo->jpeg_color_space == JCS_YCbCr ||
  529. cinfo->jpeg_color_space == JCS_BG_YCC)) {
  530. /* Custom script for YCC color images. */
  531. nscans = 10;
  532. } else {
  533. /* All-purpose script for other color spaces. */
  534. if (ncomps > MAX_COMPS_IN_SCAN)
  535. nscans = 6 * ncomps; /* 2 DC + 4 AC scans per component */
  536. else
  537. nscans = 2 + 4 * ncomps; /* 2 DC scans; 4 AC scans per component */
  538. }
  539. /* Allocate space for script.
  540. * We need to put it in the permanent pool in case the application performs
  541. * multiple compressions without changing the settings. To avoid a memory
  542. * leak if jpeg_simple_progression is called repeatedly for the same JPEG
  543. * object, we try to re-use previously allocated space, and we allocate
  544. * enough space to handle YCC even if initially asked for grayscale.
  545. */
  546. if (cinfo->script_space == NULL || cinfo->script_space_size < nscans) {
  547. cinfo->script_space_size = MAX(nscans, 10);
  548. cinfo->script_space = (jpeg_scan_info *)
  549. (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT,
  550. cinfo->script_space_size * SIZEOF(jpeg_scan_info));
  551. }
  552. scanptr = cinfo->script_space;
  553. cinfo->scan_info = scanptr;
  554. cinfo->num_scans = nscans;
  555. if (ncomps == 3 &&
  556. (cinfo->jpeg_color_space == JCS_YCbCr ||
  557. cinfo->jpeg_color_space == JCS_BG_YCC)) {
  558. /* Custom script for YCC color images. */
  559. /* Initial DC scan */
  560. scanptr = fill_dc_scans(scanptr, ncomps, 0, 1);
  561. /* Initial AC scan: get some luma data out in a hurry */
  562. scanptr = fill_a_scan(scanptr, 0, 1, 5, 0, 2);
  563. /* Chroma data is too small to be worth expending many scans on */
  564. scanptr = fill_a_scan(scanptr, 2, 1, 63, 0, 1);
  565. scanptr = fill_a_scan(scanptr, 1, 1, 63, 0, 1);
  566. /* Complete spectral selection for luma AC */
  567. scanptr = fill_a_scan(scanptr, 0, 6, 63, 0, 2);
  568. /* Refine next bit of luma AC */
  569. scanptr = fill_a_scan(scanptr, 0, 1, 63, 2, 1);
  570. /* Finish DC successive approximation */
  571. scanptr = fill_dc_scans(scanptr, ncomps, 1, 0);
  572. /* Finish AC successive approximation */
  573. scanptr = fill_a_scan(scanptr, 2, 1, 63, 1, 0);
  574. scanptr = fill_a_scan(scanptr, 1, 1, 63, 1, 0);
  575. /* Luma bottom bit comes last since it's usually largest scan */
  576. scanptr = fill_a_scan(scanptr, 0, 1, 63, 1, 0);
  577. } else {
  578. /* All-purpose script for other color spaces. */
  579. /* Successive approximation first pass */
  580. scanptr = fill_dc_scans(scanptr, ncomps, 0, 1);
  581. scanptr = fill_scans(scanptr, ncomps, 1, 5, 0, 2);
  582. scanptr = fill_scans(scanptr, ncomps, 6, 63, 0, 2);
  583. /* Successive approximation second pass */
  584. scanptr = fill_scans(scanptr, ncomps, 1, 63, 2, 1);
  585. /* Successive approximation final pass */
  586. scanptr = fill_dc_scans(scanptr, ncomps, 1, 0);
  587. scanptr = fill_scans(scanptr, ncomps, 1, 63, 1, 0);
  588. }
  589. }
  590. #endif /* C_PROGRESSIVE_SUPPORTED */