doc/help/spec-raster.html

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   8
   9 <P>CUPS raster files are device-dependent raster image files that
  10 contain a PostScript page device dictionary and device-dependent
  11 raster imagery for each page in the document. These files are
  12 used to transfer raster data from the PostScript and image file
  13 RIPs to device-dependent filters that convert the raster data to
  14 a printable format.</P>
  15
  16 <P>CUPS 1.0 and 1.1 used a version 1 raster format. CUPS 1.2
  17 introduces version 2 (compressed) and version 3 (uncompressed)
  18 formats that are a superset of the version 1 format. Applications
  19 using the CUPS Imaging API (the cupsRaster* functions) can read
  20 all formats without code changes.</P>
  21
  22 <P>The registered MIME media type for CUPS raster files is
  23 <CODE>application/vnd.cups-raster</CODE>.</P>
  24
  25
  26 <H2 CLASS="title"><A NAME="V1">Version 1 Raster File Format</A></H2>
  27
  28 <P>A version 1 raster file begins with a 32-bit synchronization
  29 word: 0x52615374 ("RaSt") for big-endian architectures and
  30 0x74536152 ("tSaR") for little-endian architectures. The writer
  31 of the raster file will use the native word order, and the reader
  32 is responsible for detecting a reversed word order file and
  33 swapping bytes as needed. The CUPS Imaging API raster functions
  34 perform this function automatically.</P>
  35
  36 <P>Following the synchronization word are a series of raster
  37 pages. Each page starts with a page device dictionary header and
  38 is followed immediately by the (uncompressed, raw) raster data
  39 for that page.</P>
  40
  41 <DIV CLASS="table"><TABLE SUMMARY="CUPS Version 1 Raster Page Device Dictionary">
  42 <CAPTION><A NAME="TABLE1">Table 1: CUPS Version 1 Raster Page Device Dictionary</A></CAPTION>
  43 <THEAD>
  44 <TR>
  45         <TH>Bytes</TH>
  46         <TH>Type</TH>
  47         <TH>Description</TH>
  48         <TH>Values</TH>
  49 </TR>
  50 </THEAD>
  51 <TBODY>
  52 <TR>
  53         <TD>0-63</TD>
  54         <TD>C String</TD>
  55         <TD>MediaClass</TD>
  56         <TD>Media class string</TD>
  57 </TR>
  58 <TR>
  59         <TD>64-127</TD>
  60         <TD>C String</TD>
  61         <TD>MediaColor</TD>
  62         <TD>Media color string</TD>
  63 </TR>
  64 <TR>
  65         <TD>128-191</TD>
  66         <TD>C String</TD>
  67         <TD>MediaType</TD>
  68         <TD>Media type string</TD>
  69 </TR>
  70 <TR>
  71         <TD>192-255</TD>
  72         <TD>C String</TD>
  73         <TD>OutputType</TD>
  74         <TD>Output type string</TD>
  75 </TR>
  76 <TR>
  77         <TD>256-259</TD>
  78         <TD>Unsigned Integer</TD>
  79         <TD>AdvanceDistance</TD>
  80         <TD>0 to 2<SUP>32</SUP> - 1 points</TD>
  81 </TR>
  82 <TR>
  83         <TD>260-263</TD>
  84         <TD>Unsigned Integer</TD>
  85         <TD>AdvanceMedia</TD>
  86         <TD>0 = Never advance roll<BR>
  87         1 = Advance roll after file<BR>
  88         2 = Advance roll after job<BR>
  89         3 = Advance roll after set<BR>
  90         4 = Advance roll after page</TD>
  91 </TR>
  92 <TR>
  93         <TD>264-267</TD>
  94         <TD>Unsigned Integer</TD>
  95         <TD>Collate</TD>
  96         <TD>0 = do not collate copies<BR>
  97         1 = collate copies</TD>
  98 </TR>
  99 <TR>
 100         <TD>268-271</TD>
 101         <TD>Unsigned Integer</TD>
 102         <TD>CutMedia</TD>
 103         <TD>0 = Never cut media<BR>
 104         1 = Cut roll after file<BR>
 105         2 = Cut roll after job<BR>
 106         3 = Cut roll after set<BR>
 107         4 = Cut roll after page</TD>
 108 </TR>
 109 <TR>
 110         <TD>272-275</TD>
 111         <TD>Unsigned Integer</TD>
 112         <TD>Duplex</TD>
 113         <TD>0 = Print single-sided<BR>
 114         1 = Print double-sided</TD>
 115 </TR>
 116 <TR>
 117         <TD>276-283</TD>
 118         <TD>Unsigned Integers (2)</TD>
 119         <TD>HWResolution</TD>
 120         <TD>Horizontal and vertical resolution in dots-per-inch.</TD>
 121 </TR>
 122 <TR>
 123         <TD>284-299</TD>
 124         <TD>Unsigned Integers (4)</TD>
 125         <TD>ImagingBoundingBox</TD>
 126         <TD>Four integers giving the left, bottom, right, and top positions
 127         of the page bounding box in points</TD>
 128 </TR>
 129 <TR>
 130         <TD>300-303</TD>
 131         <TD>Unsigned Integer</TD>
 132         <TD>InsertSheet</TD>
 133         <TD>0 = Do not insert separator sheets<BR>
 134         1 = Insert separator sheets</TD>
 135 </TR>
 136 <TR>
 137         <TD>304-307</TD>
 138         <TD>Unsigned Integer</TD>
 139         <TD>Jog</TD>
 140         <TD>0 = Do no jog pages<BR>
 141         1 = Jog pages after file<BR>
 142         2 = Jog pages after job<BR>
 143         3 = Jog pages after set</TD>
 144 </TR>
 145 <TR>
 146         <TD>308-311</TD>
 147         <TD>Unsigned Integer</TD>
 148         <TD>LeadingEdge</TD>
 149         <TD>0 = Top edge is first<BR>
 150         1 = Right edge is first<BR>
 151         2 = Bottom edge is first<BR>
 152         3 = Left edge is first</TD>
 153 </TR>
 154 <TR>
 155         <TD>312-319</TD>
 156         <TD>Unsigned Integers (2)</TD>
 157         <TD>Margins</TD>
 158         <TD>Left and bottom origin of image in points</TD>
 159 </TR>
 160 <TR>
 161         <TD>320-323</TD>
 162         <TD>Unsigned Integer</TD>
 163         <TD>ManualFeed</TD>
 164         <TD>0 = Do not manually feed media<BR>
 165         1 = Manually feed media</TD>
 166 </TR>
 167 <TR>
 168         <TD>324-327</TD>
 169         <TD>Unsigned Integer</TD>
 170         <TD>MediaPosition</TD>
 171         <TD>Input slot position from 0 to N</TD>
 172 </TR>
 173 <TR>
 174         <TD>328-331</TD>
 175         <TD>Unsigned Integer</TD>
 176         <TD>MediaWeight</TD>
 177         <TD>Media weight in grams per meter squared</TD>
 178 </TR>
 179 <TR>
 180         <TD>332-335</TD>
 181         <TD>Unsigned Integer</TD>
 182         <TD>MirrorPrint</TD>
 183         <TD>0 = Do not mirror prints<BR>
 184         1 = Mirror prints</TD>
 185 </TR>
 186 <TR>
 187         <TD>336-339</TD>
 188         <TD>Unsigned Integer</TD>
 189         <TD>NegativePrint</TD>
 190         <TD>0 = Do not invert prints<BR>
 191         1 = Invert prints</TD>
 192 </TR>
 193 <TR>
 194         <TD>340-343</TD>
 195         <TD>Unsigned Integer</TD>
 196         <TD>NumCopies</TD>
 197         <TD>1 to 2<SUP>32</SUP> - 1</TD>
 198 </TR>
 199 <TR>
 200         <TD>344-347</TD>
 201         <TD>Unsigned Integer</TD>
 202         <TD>Orientation</TD>
 203         <TD>0 = Do not rotate page<BR>
 204         1 = Rotate page counter-clockwise<BR>
 205         2 = Turn page upside down<BR>
 206         3 = Rotate page clockwise</TD>
 207 </TR>
 208 <TR>
 209         <TD>348-351</TD>
 210         <TD>Unsigned Integer</TD>
 211         <TD>OutputFaceUp</TD>
 212         <TD>0 = Output face down<BR>
 213         1 = Output face up</TD>
 214 </TR>
 215 <TR>
 216         <TD>352-359</TD>
 217         <TD>Unsigned Integers (2)</TD>
 218         <TD>PageSize</TD>
 219         <TD>Width and length in points</TD>
 220 </TR>
 221 <TR>
 222         <TD>360-363</TD>
 223         <TD>Unsigned Integer</TD>
 224         <TD>Separations</TD>
 225         <TD>0 = Print composite image<BR>
 226         1 = Print color separations</TD>
 227 </TR>
 228 <TR>
 229         <TD>364-367</TD>
 230         <TD>Unsigned Integer</TD>
 231         <TD>TraySwitch</TD>
 232         <TD>0 = Do not change trays if selected tray is empty<BR>
 233         1 = Change trays if selected tray is empty</TD>
 234 </TR>
 235 <TR>
 236         <TD>368-371</TD>
 237         <TD>Unsigned Integer</TD>
 238         <TD>Tumble</TD>
 239         <TD>0 = Do not rotate even pages when duplexing<BR>
 240         1 = Rotate even pages when duplexing</TD>
 241 </TR>
 242 <TR>
 243         <TD>372-375</TD>
 244         <TD>Unsigned Integer</TD>
 245         <TD>cupsWidth</TD>
 246         <TD>Width of page image in pixels</TD>
 247 </TR>
 248 <TR>
 249         <TD>376-379</TD>
 250         <TD>Unsigned Integer</TD>
 251         <TD>cupsHeight</TD>
 252         <TD>Height of page image in pixels</TD>
 253 </TR>
 254 <TR>
 255         <TD>380-383</TD>
 256         <TD>Unsigned Integer</TD>
 257         <TD>cupsMediaType</TD>
 258         <TD>Driver-specific 0 to 2<SUP>32</SUP> - 1</TD>
 259 </TR>
 260 <TR>
 261         <TD>384-387</TD>
 262         <TD>Unsigned Integer</TD>
 263         <TD>cupsBitsPerColor</TD>
 264         <TD>1, 2, 4, 8 bits for version 1 raster files<BR>
 265         1, 2, 4, 8, and 16 bits for version 2 raster files</TD>
 266 </TR>
 267 <TR>
 268         <TD>388-391</TD>
 269         <TD>Unsigned Integer</TD>
 270         <TD>cupsBitsPerPixel</TD>
 271         <TD>1 to 32 bits for version 1 raster files<BR>
 272         1 to 64 bits for version 2 raster files</TD>
 273 </TR>
 274 <TR>
 275         <TD>392-395</TD>
 276         <TD>Unsigned Integer</TD>
 277         <TD>cupsBytesPerLine</TD>
 278         <TD>1 to 2<SUP>32</SUP> - 1 bytes</TD>
 279 </TR>
 280 <TR>
 281         <TD>396-399</TD>
 282         <TD>Unsigned Integer</TD>
 283         <TD>cupsColorOrder</TD>
 284         <TD>0 = chunky pixels (CMYK CMYK CMYK)<BR>
 285         1 = banded pixels (CCC MMM YYY KKK)<BR>
 286         2 = planar pixels (CCC... MMM... YYY... KKK...)</TD>
 287 </TR>
 288 <TR>
 289         <TD>400-403</TD>
 290         <TD>Unsigned Integer</TD>
 291         <TD>cupsColorSpace</TD>
 292         <TD>0 = white (sRGB)<BR>
 293         1 = RGB (sRGB)<BR>
 294         2 = RGBA (sRGB)<BR>
 295         3 = black<BR>
 296         4 = CMY<BR>
 297         5 = YMC<BR>
 298         6 = CMYK<BR>
 299         7 = YMCK<BR>
 300         8 = KCMY<BR>
 301         9 = KCMYcm<BR>
 302         10 = GMCK<BR>
 303         11 = GMCS<BR>
 304         12 = WHITE<BR>
 305         13 = GOLD<BR>
 306         14 = SILVER<BR>
 307         15 = CIE XYZ<BR>
 308         16 = CIE Lab<BR>
 309         17 = RGBW (sRGB)<BR>
 310         32 = ICC1 (CIE Lab with hint for 1 color)<BR>
 311         33 = ICC2 (CIE Lab with hint for 2 colors)<BR>
 312         34 = ICC3 (CIE Lab with hint for 3 colors)<BR>
 313         35 = ICC4 (CIE Lab with hint for 4 colors)<BR>
 314         36 = ICC5 (CIE Lab with hint for 5 colors)<BR>
 315         37 = ICC6 (CIE Lab with hint for 6 colors)<BR>
 316         38 = ICC7 (CIE Lab with hint for 7 colors)<BR>
 317         39 = ICC8 (CIE Lab with hint for 8 colors)<BR>
 318         40 = ICC9 (CIE Lab with hint for 9 colors)<BR>
 319         41 = ICCA (CIE Lab with hint for 10 colors)<BR>
 320         42 = ICCB (CIE Lab with hint for 11 colors)<BR>
 321         43 = ICCC (CIE Lab with hint for 12 colors)<BR>
 322         44 = ICCD (CIE Lab with hint for 13 colors)<BR>
 323         45 = ICCE (CIE Lab with hint for 14 colors)<BR>
 324         46 = ICCF (CIE Lab with hint for 15 colors)<BR>
 325         </TD>
 326 </TR>
 327 <TR>
 328         <TD>404-407</TD>
 329         <TD>Unsigned Integer</TD>
 330         <TD>cupsCompression</TD>
 331         <TD>Driver-specific 0 to 2<SUP>32</SUP> - 1</TD>
 332 </TR>
 333 <TR>
 334         <TD>408-411</TD>
 335         <TD>Unsigned Integer</TD>
 336         <TD>cupsRowCount</TD>
 337         <TD>Driver-specific 0 to 2<SUP>32</SUP> - 1</TD>
 338 </TR>
 339 <TR>
 340         <TD>412-415</TD>
 341         <TD>Unsigned Integer</TD>
 342         <TD>cupsRowFeed</TD>
 343         <TD>Driver-specific 0 to 2<SUP>32</SUP> - 1</TD>
 344 </TR>
 345 <TR>
 346         <TD>416-419</TD>
 347         <TD>Unsigned Integer</TD>
 348         <TD>cupsRowStep</TD>
 349         <TD>Driver-specific 0 to 2<SUP>32</SUP> - 1</TD>
 350 </TR>
 351 </TBODY>
 352 </TABLE></DIV>
 353
 354
 355 <H2 CLASS="title"><A NAME="V2">Version 2 Raster File Format</A></H2>
 356
 357 <P>A version 2 raster file begins with a 32-bit synchronization
 358 word: 0x52615332 ("RaS2") for big-endian architectures and
 359 0x32536152 ("2SaR") for little-endian architectures. The writer
 360 of the raster file will use the native word order, and the reader
 361 is responsible for detecting a reversed word order file and
 362 swapping bytes as needed. The CUPS Imaging API raster functions
 363 perform this function automatically.</P>
 364
 365 <P>Following the synchronization word are a series of raster
 366 pages. Each page starts with a version 2 page device dictionary
 367 header and is followed immediately by the compressed raster data
 368 for that page.</P>
 369
 370 <DIV CLASS="table"><TABLE SUMMARY="CUPS Version 2 Raster Page Device Dictionary">
 371 <CAPTION><A NAME="TABLE2">Table 2: CUPS Version 2 Raster Page Device Dictionary</A></CAPTION>
 372 <THEAD>
 373 <TR>
 374         <TH>Bytes</TH>
 375         <TH>Type</TH>
 376         <TH>Description</TH>
 377         <TH>Values</TH>
 378 </TR>
 379 </THEAD>
 380 <TBODY>
 381 <TR>
 382         <TD>0-419</TD>
 383         <TD>Version 1 header data</TD>
 384         <TD>See Table 1</TD>
 385 </TR>
 386 <TR>
 387         <TD>420-423</TD>
 388         <TD>Unsigned Integer</TD>
 389         <TD>cupsNumColors</TD>
 390         <TD>1 to 6 colors</TD>
 391 </TR>
 392 <TR>
 393         <TD>424-427</TD>
 394         <TD>IEEE Single Precision</TD>
 395         <TD>cupsBorderlessScalingFactor</TD>
 396         <TD>0.0 or 1.0 or greater</TD>
 397 </TR>
 398 <TR>
 399         <TD>428-435</TD>
 400         <TD>IEEE Single Precision (2)</TD>
 401         <TD>cupsPageSize</TD>
 402         <TD>Width and length in points</TD>
 403 </TR>
 404 <TR>
 405         <TD>436-451</TD>
 406         <TD>IEEE Single Precision (4)</TD>
 407         <TD>cupsImagingBBox</TD>
 408         <TD>Four floating point numbers giving the left, bottom,
 409         right, and top positions of the page bounding box in
 410         points</TD>
 411 </TR>
 412 <TR>
 413         <TD>452-515</TD>
 414         <TD>Unsigned Integers (16)</TD>
 415         <TD>cupsInteger</TD>
 416         <TD>16 driver-defined integer values</TD>
 417 </TR>
 418 <TR>
 419         <TD>516-579</TD>
 420         <TD>IEEE Single Precision (16)</TD>
 421         <TD>cupsReal</TD>
 422         <TD>16 driver-defined floating point values</TD>
 423 </TR>
 424 <TR>
 425         <TD>580-1603</TD>
 426         <TD>C Strings (16x64)</TD>
 427         <TD>cupsString</TD>
 428         <TD>16 driver-defined strings</TD>
 429 </TR>
 430 <TR>
 431         <TD>1604-1667</TD>
 432         <TD>C String</TD>
 433         <TD>cupsMarkerType</TD>
 434         <TD>Ink/toner type string</TD>
 435 </TR>
 436 <TR>
 437         <TD>1668-1731</TD>
 438         <TD>C String</TD>
 439         <TD>cupsRenderingIntent</TD>
 440         <TD>Color rendering intent string</TD>
 441 </TR>
 442 <TR>
 443         <TD>1732-1795</TD>
 444         <TD>C String</TD>
 445         <TD>cupsPageSizeName</TD>
 446         <TD>Page size name/keyword string from PPD</TD>
 447 </TR>
 448 </TBODY>
 449 </TABLE></DIV>
 450
 451 <H3><A NAME="COMPRESSION">Compressed Raster Data Format</A></H3>
 452
 453 <P>The version 2 raster data is compressed using a modified TIFF
 454 packbits algorithm. Lines are grouped into an integral number of
 455 color values based upon the <CODE>cupsColorOrder</CODE>
 456 setting:</P>
 457
 458 <DIV CLASS="table"><TABLE SUMMARY="Color Value Sizes">
 459 <CAPTION><A NAME="TABLE3">Table 3: Color Value Sizes</A></CAPTION>
 460 <TR>
 461         <TH>cupsColorOrder</TH>
 462         <TH>Bytes per color value</TH>
 463 </TR>
 464 <TR>
 465         <TD>0 (chunky)</TD>
 466         <TD>(<CODE>cupsBitsPerPixel</CODE> + 7) / 8</TD>
 467 </TR>
 468 <TR>
 469         <TD>1 (banded)</TD>
 470         <TD>(<CODE>cupsBitsPerColor</CODE> + 7) / 8</TD>
 471 </TR>
 472 <TR>
 473         <TD>2 (planar)</TD>
 474         <TD>(<CODE>cupsBitsPerColor</CODE> + 7) / 8</TD>
 475 </TR>
 476 </TABLE></DIV>
 477
 478 <P>Each line of raster data begins with a repetition count from 1
 479 to 256 that is encoded using a single byte of "count - 1".</P>
 480
 481 <P>After the repetition count, whole color values for that line
 482 are run-length encoded using the TIFF packbits algorithm. 1 to
 483 128 repeated colors are encoded using an initial byte of "count -
 484 1" followed by the color value byte(s). 2 to 128 non-repeating
 485 colors are encoded using an initial byte of "257 - count"
 486 followed by the color value bytes.</P>
 487
 488
 489 <H2 CLASS="title"><A NAME="V3">Version 3 Raster File Format</A></H2>
 490
 491 <P>A version 3 raster file begins with a 32-bit synchronization
 492 word: 0x52615333 ("RaS3") for big-endian architectures and
 493 0x33536152 ("3SaR") for little-endian architectures. The writer
 494 of the raster file will use the native word order, and the reader
 495 is responsible for detecting a reversed word order file and
 496 swapping bytes as needed. The CUPS Imaging API raster functions
 497 perform this function automatically.</P>
 498
 499 <P>Following the synchronization word are a series of raster
 500 pages. Each page starts with a version 2 page device dictionary
 501 header and is followed immediately by the uncompressed raster data
 502 for that page.</P>
 503
 504
 505 <H2 CLASS="title"><A NAME="ENCODING">Pixel Value Coding</A></H2>
 506
 507 <P>The following sections describe the encoding and decoding of
 508 the color values in a CUPS raster file. In general, colors are
 509 packed into the minimum number of bytes, with special
 510 consideration provided for efficiency of encoding and access.
 511 Multi-byte values are stored in the native byte order and
 512 automatically swapped as needed when reading them using the CUPS
 513 imaging API.</P>
 514
 515 <H3>CUPS_ORDER_CHUNKED</H3>
 516
 517 <P>The chunked order provides the pixel value packed in a single
 518 place. Pixel values with 8 or more bits per color are stored as
 519 an array of colors in order, e.g. for
 520 <CODE>CUPS_CSPACE_RGB</CODE> you will see 8/16-bits of red, then
 521 blue, then green, then red, green, blue, etc. Pixel values with
 522 less than 8 bits per color are packed together as shown in Table
 523 4. <I>Multi-byte pixel values are stored in the native word
 524 order, just as for 16-bit color values.</I></P>
 525
 526 <DIV CLASS="table"><TABLE SUMMARY="Chunked Color Values">
 527 <CAPTION><A NAME="TABLE4">Table 4: Chunked Color Values</A></CAPTION>
 528 <THEAD>
 529 <TR>
 530         <TH>Bits</TH>
 531         <TH>1-color</TH>
 532         <TH>3-color</TH>
 533         <TH>4-color</TH>
 534         <TH>6-color</TH>
 535 </TR>
 536 </THEAD>
 537 <TBODY>
 538 <TR>
 539         <TD>1</TD>
 540         <TD>W/W/W/W/W/W/W/W</TD>
 541         <TD>0RGB/0RGB</TD>
 542         <TD>CMYK/CMYK</TD>
 543         <TD>00KCMYcm</TD>
 544 </TR>
 545 <TR>
 546         <TD>2</TD>
 547         <TD>WW/WW/WW/WW</TD>
 548         <TD>00RRGGBB</TD>
 549         <TD>CCMMYYKK</TD>
 550         <TD>N/A</TD>
 551 </TR>
 552 <TR>
 553         <TD>4</TD>
 554         <TD>WWWW/WWWW</TD>
 555         <TD>0000RRRRGGGGBBBB<BR>
 556         <I>(multi-byte)</I></TD>
 557         <TD>CCCCMMMMYYYYKKKK<BR>
 558         <I>(multi-byte)</I></TD>
 559         <TD>N/A</TD>
 560 </TR>
 561 </TBODY>
 562 </TABLE></DIV>
 563
 564 <H3>CUPS_ORDER_BANDED</H3>
 565
 566 <P>The banded order provides each color as a separate line of
 567 data. Each color plane for a line is written in sequence, e.g.
 568 for the <CODE>CUPS_CSPACE_CMYK</CODE> colorspace you would see
 569 all of the cyan pixels for a line followed by the magenta,
 570 yellow, and black pixels for that line. This is repeated for all
 571 of the lines on the page. Color values are packed starting with
 572 the most-significant bit (MSB) first.</P>
 573
 574 <H3>CUPS_ORDER_PLANAR</H3>
 575
 576 <P>The planar order provides each color as a separate page of
 577 data using a shared page header. Each color plane for a page is
 578 written in sequence, e.g. for the <CODE>CUPS_CSPACE_CMYK</CODE>
 579 colorspace you would see all of the cyan pixels for a page
 580 followed by the magenta, yellow, and black pixels for that page.
 581 Color values are packed starting with the most-significant bit
 582 (MSB) first. Each line starts on an 8-bit boundary.</P>
 583
 584 <H3>CUPS_CSPACE_W, CUPS_CSPACE_RGB, CUPS_CSPACE_RGBA, and
 585 CUPS_CSPACE_RGBW</H3>
 586
 587 <P>These colorspaces use the sRGB colorspace definition and
 588 whitepoint.</P>
 589
 590 <H3>CUPS_CSPACE_KCMYcm</H3>
 591
 592 <P>When <CODE>cupsBitsPerColor</CODE> is 1, 6 color planes are
 593 provided - black, cyan, magenta, yellow, light cyan, and light
 594 magenta. When <CODE>cupsBitsPerColor</CODE> is greater than 1, 4
 595 color planes are provided using the <CODE>CUPS_CSPACE_KCMY</CODE>
 596 colorspace instead.</P>
 597
 598 <P>When <CODE>cupsColorOrder</CODE> is
 599 <CODE>CUPS_ORDER_CHUNKED</CODE>, bit 5 corresponds to black and
 600 bit 0 corresponds to light magenta. For
 601 <CODE>CUPS_ORDER_BANDED</CODE> and
 602 <CODE>CUPS_ORDER_PLANAR</CODE>, each color plane is encoded
 603 separately.</P>
 604
 605 <H3>CUPS_CSPACE_CIELab and CUPS_CSPACE_ICCn</H3>
 606
 607 <P>These colorspaces map a CIE Lab color value with a D65
 608 whitepoint to either a 8- or 16-bit per color chunked
 609 (<CODE>CUPS_ORDER_CHUNKED</CODE>) format; the banded
 610 (<CODE>CUPS_ORDER_BANDED</CODE>) and planar
 611 (<CODE>CUPS_ORDER_PLANAR</CODE>) color orders are not
 612 supported.</P>
 613
 614 <P>The values are encoded and decoded using the following
 615 formulas:</P>
 616
 617 <UL>
 618
 619         <LI>8-bit Encoding:<BR>
 620         <I>L8 = 2.55 * L + 0.5<BR>
 621         a8 = a + 128.5<BR>
 622         b8 = b + 128.5<BR>
 623         &nbsp;</I></LI>
 624
 625         <LI>8-bit Decoding:<BR>
 626         <I>L = L8 / 2.55<BR>
 627         a = a8 - 128<BR>
 628         b = b8 - 128<BR>
 629         &nbsp;</I></LI>
 630
 631         <LI>16-bit Encoding:<BR>
 632         <I>L16 = 655.35 * L + 0.5<BR>
 633         a16 = 256 * (a + 128) + 0.5<BR>
 634         b16 = 256 * (b + 128) + 0.5<BR>
 635         &nbsp;</I></LI>
 636
 637         <LI>16-bit Decoding:<BR>
 638         <I>L = L16 / 655.35<BR>
 639         a = a16 / 256 - 128<BR>
 640         b = b16 / 256 - 128<BR>
 641         &nbsp;</I></LI>
 642
 643 </UL>
 644
 645 <H3>CUPS_CSPACE_CIEXYZ</H3>
 646
 647 <P>These colorspaces map a CIE XYZ color value with a D65
 648 whitepoint to either a 8- or 16-bit per color chunked
 649 (<CODE>CUPS_ORDER_CHUNKED</CODE>) format; the banded
 650 (<CODE>CUPS_ORDER_BANDED</CODE>) and planar
 651 (<CODE>CUPS_ORDER_PLANAR</CODE>) color orders are not
 652 supported.</P>
 653
 654 <P>The values are encoded and decoded using the following
 655 formulas:</P>
 656
 657 <UL>
 658
 659         <LI>8-bit Encoding:<BR>
 660         <I>X8 = 231.8181 * X + 0.5<BR>
 661         Y8 = 231.8181 * Y + 0.5<BR>
 662         Z8 = 231.8181 * Z + 0.5<BR>
 663         &nbsp;</I></LI>
 664
 665         <LI>8-bit Decoding:<BR>
 666         <I>X = X8 / 231.8181<BR>
 667         Y = Y8 / 231.8181<BR>
 668         Z = Z8 / 231.8181<BR>
 669         &nbsp;</I></LI>
 670
 671         <LI>16-bit Encoding:<BR>
 672         <I>X16 = 59577.2727 * X + 0.5<BR>
 673         Y16 = 59577.2727 * Y + 0.5<BR>
 674         Z16 = 59577.2727 * Z + 0.5<BR>
 675         &nbsp;</I></LI>
 676
 677         <LI>16-bit Decoding:<BR>
 678         <I>X = X16 / 59577.2727<BR>
 679         Y = Y16 / 59577.2727<BR>
 680         Z = Z16 / 59577.2727<BR>
 681         &nbsp;</I></LI>
 682
 683 </UL>
 684
 685 <P>The scaling factor for XYZ values is 1/1.1, or 231.8181 for
 686 8-bit values and 59577.2727 for 16-bit values. This allows for a
 687 slight overflow of XYZ values when converting from RGB, improving
 688 accuracy.</P>
 689
 690
 691 <H2 CLASS="title"><A NAME="HISTORY">Change History</A></H2>
 692
 693 <H3>Changes in CUPS 1.2.2</H3>
 694
 695 <ul>
 696
 697         <li>Added version 3 (uncompressed) format.</li>
 698
 699 </ul>
 700
 701
 702 <H3>Changes in CUPS 1.2.1</H3>
 703
 704 <ul>
 705
 706         <li>Added new sections on coding pixel values.</li>
 707
 708         <li>Clarified definitions of color spaces.</li>
 709
 710 </ul>
 711
 712
 713 <H3>Changes in CUPS 1.2</H3>
 714
 715 <ul>
 716
 717         <li>Bumped raster version to 2</li>
 718
 719         <li>Added RGBW colorspace</li>
 720
 721         <li>Added 16 bit per color support</li>
 722
 723         <li>Added cupsNumColors, cupsBorderlessScalingFactor,
 724         cupsPageSize, cupsImagingBBox, cupsInteger, cupsReal,
 725         cupsString, cupsMarkerType, cupsRenderingIntent, and
 726         cupsPageSizeName attributes to the page device
 727         dictionary</li>
 728
 729         <li>Added raster data compression</li>
 730
 731         <li>Added data type column to device dictionary
 732         documentation.</li>
 733
 734 </ul>
 735
 736 <h3>Changes in CUPS 1.1.19</h3>
 737
 738 <ul>
 739
 740         <li>Added ICC and CIE colorspaces.</li>
 741
 742 </ul>
 743
 744 </BODY>
 745 </HTML>