doc/help/spec-raster.html

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