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'4' -- Possible downref: Non-RFC (?) normative reference: ref. '6' ** Obsolete normative reference: RFC 2301 (ref. '7') (Obsoleted by RFC 3949) Summary: 5 errors (**), 0 flaws (~~), 19 warnings (==), 4 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 1 IETF Fax working group Graham Klyne 2 Internet Draft Content Technologies 3 Category: Work-in-progress Lloyd McIntyre 4 Xerox Corporation 5 5 January 2000 6 Expires: July 2000 8 Content Feature Schema for Internet Fax (V2) 9 11 Status of this memo 13 This document is an Internet-Draft and is in full conformance with 14 all provisions of Section 10 of RFC 2026. 16 Internet-Drafts are working documents of the Internet Engineering 17 Task Force (IETF), its areas, and its working groups. Note that 18 other groups may also distribute working documents as Internet- 19 Drafts. 21 Internet-Drafts are draft documents valid for a maximum of six 22 months and may be updated, replaced, or obsoleted by other 23 documents at any time. It is inappropriate to use Internet-Drafts 24 as reference material or to cite them other than as ``work in 25 progress''. 27 The list of current Internet-Drafts can be accessed at 28 http://www.ietf.org/ietf/1id-abstracts.txt 30 The list of Internet-Draft Shadow Directories can be accessed at 31 http://www.ietf.org/shadow.html. 33 To view the entire list of current Internet-Drafts, please check 34 the "1id-abstracts.txt" listing contained in the Internet-Drafts 35 Shadow Directories on ftp.is.co.za (Africa), ftp.nordu.net 36 (Northern Europe), ftp.nis.garr.it (Southern Europe), munnari.oz.au 37 (Pacific Rim), ftp.ietf.org (US East Coast), or ftp.isi.edu (US 38 West Coast). 40 Copyright Notice 42 Copyright (C) The Internet Society 1999. All Rights Reserved. 44 Abstract 46 This document revises the content feature schema described in RFC 47 2531, with clarifications to some of the feature tag descriptions 48 and addition of one new feature tag. 50 This content feature schema is a profile of the media feature 51 description mechanisms [1,2,3] for use in performing capability 52 exchange between extended Internet fax systems [5]. 54 Internet Draft Content Feature Schema for Internet Fax (V2) 55 5 January 57 Table of contents 59 1. Introduction ............................................3 60 1.1 Organization of this document 3 61 1.2 Terminology and document conventions 3 62 1.3 Discussion of this document 4 63 2. Fax feature schema syntax ...............................4 64 3. Internet fax feature tags ...............................5 65 3.1 Image size 5 66 3.2 Resolution 6 67 3.3 Media type 6 68 3.4 Paper Size 7 69 3.5 Color capability 7 70 3.6 Color model 8 71 3.7 Image coding 11 72 3.8 MRC mode 13 73 4. Examples ................................................13 74 4.1 Simple mode Internet fax system 14 75 4.2 High-end black-and-white Internet fax system 14 76 4.3 Grey-scale Internet fax system 15 77 4.4 Full-color Internet fax system (JPEG only) 16 78 4.5 Full-color Internet fax system (JPEG and JBIG) 17 79 4.6 Full-color Internet fax system (MRC) 18 80 4.7 Sender and receiver feature matching 20 81 5. IANA considerations .....................................22 82 6. Security considerations .................................22 83 6.1 Capability descriptions and mechanisms 22 84 6.2 Specific threats 22 85 7. Acknowledgements ........................................22 86 8. References ..............................................23 87 9. Authors' addresses ......................................26 88 Appendix A: Feature registrations ..........................27 89 A.1 Image size 27 90 A.2 Resolution aspect ratio 29 91 A.3 Color levels 31 92 A.4 Color space 33 93 A.5 CIELAB color illuminant 36 94 A.6 CIELAB color depth 38 95 A.7 CIELAB color gamut 40 96 A.8 Image file structure 44 97 A.9 Image data coding 46 98 A.10 Image coding constraint 48 99 A.11 JBIG stripe size 50 100 A.12 Image interleave 52 101 A.13 Color subsampling 54 102 A.14 MRC availability and mode 56 103 A.15 MRC maximum stripe size 58 104 Appendix B: TIFF mode descriptions .........................60 105 Appendix C: Changes from RFC 2531 ..........................66 107 Internet Draft Content Feature Schema for Internet Fax (V2) 108 5 January 110 Full copyright statement ...................................67 112 1. Introduction 114 This document revises the content feature schema described in RFC 115 2531, with clarifications to some of the feature tag descriptions 116 and addition of one new feature tag. 118 This content feature schema is a profile of the media feature 119 description mechanisms [1,2,3] for use in performing capability 120 exchange between Extended Internet Fax systems [5]. 122 The media feature description mechanisms not describe any specific 123 mechanisms for communicating capability information, but do presume 124 that any such mechanisms will transfer textual values. I 125 conjunction with this feature schema, they specify a textual format 126 to be used for describing Internet Fax capability information. 128 The range of capabilities that can be indicated are based on those 129 covered by the TIFF file format for Internet fax [7] and Group 3 130 facsimile [6]. A companion document [4] describes the relationship 131 and mapping between this schema and Group 3 fax capabilities. 133 1.1 Organization of this document 135 Section 2 specifies the overall syntax for fax feature descriptions 136 by reference to the media feature registration and syntax documents 137 [1,2]. 139 Section 3 enumerates the feature tags that are to be recognized and 140 processed by extended Internet fax systems, according to their 141 capabilities. 143 Appendix A contains additional feature tag registrations for media 144 features that are specific to fax and for which no applicable 145 registration already exists. These are presented in the form 146 prescribed by the media feature registration procedure [1]. 148 1.2 Terminology and document conventions 150 The term "extended Internet fax system" is used to describe any 151 software, device or combination of these that conforms to the 152 specification "Extended Facsimile Using Internet Mail" [5]. 154 "capability exchange" describes any transfer of information between 155 communicating systems that is used to indicate system capabilities 156 and hence determine the form of data transferred. This term covers 157 both one-way and two-way transfers of capability information. 159 Internet Draft Content Feature Schema for Internet Fax (V2) 160 5 January 162 "capability identification" is a particular form of capability 163 exchange in which a receiving system provides capability 164 information to a sending system. 166 "capability description" is a collection of data presented in some 167 specific format that describes the capabilities of some 168 communicating entity. It may exist separately from any specific 169 capability exchange mechanism. 171 NOTE: Comments like this provide additional nonessential 172 information about the rationale behind this document. 173 Such information is not needed for building a conformant 174 implementation, but may help those who wish to understand 175 the design in greater depth. 177 1.3 Discussion of this document 179 Discussion of this document should take place on the Internet fax 180 mailing list hosted by the Internet Mail Consortium (IMC). Please 181 send comments regarding this document to: 183 ietf-fax@imc.org 185 To subscribe to this list, send a message with the body 'subscribe' 186 to "ietf-fax-request@imc.org". 188 To see what has gone on before you subscribed, please see the 189 mailing list archive at: 191 http://www.imc.org/ietf-fax/ 193 2. Fax feature schema syntax 195 The syntax for the fax feature schema is described by "A syntax for 196 describing media feature sets" [2]. This in turn calls upon media 197 feature tags that may be registered according to the procedure 198 described in "Media Feature Tag Registration Procedure" [1]. 200 NOTE: Media feature registration provides a base 201 vocabulary of features that correspond to media handling 202 capabilities. The feature set syntax provides a 203 mechanism and format for combining these to describe 204 combinations of features. This memo indicates those 205 features that may be associated with extended Internet 206 fax systems. 208 Internet Draft Content Feature Schema for Internet Fax (V2) 209 5 January 211 3. Internet fax feature tags 213 This section enumerates and briefly describes a number of feature 214 tags that are defined for use with extended Internet fax systems 215 and applications. These tags may be used also by other systems and 216 applications that support corresponding capabilities. 218 The feature tags presented below are those that an extended 219 Internet fax system is expected to recognize its ability or non- 220 ability to handle. 222 Definitive descriptions of feature tags are indicated by reference 223 to their registration according to the media feature registration 224 procedure [1] (some of which are appended to this document) 226 NOTE: The presence of a feature tag in this list does 227 not mean that an extended Internet fax system must have 228 that capability; rather, it must recognize the feature 229 tag and deal with it according to the capabilities that 230 it does have. 232 Further, an extended Internet fax system is not prevented 233 from recognizing and offering additional feature tags. 234 The list below is intended to provide a basic vocabulary 235 that all extended Internet fax systems can use in a 236 consistent fashion. 238 If an unrecognized or unused feature tag is received, the 239 feature set matching rule (described in [2]) operates so 240 that tag is effectively ignored. 242 3.1 Image size 244 Feature tag name Legal values 245 ---------------- ------------ 246 size-x (>0) 247 size-y (>0) 249 Reference: this document, Appendix A. 251 These feature values indicate a rendered document size in inches. 253 Where the actual size is measured in millimetres, a conversion 254 factor of 10/254 may be applied to yield an exact inch-based value. 256 Internet Draft Content Feature Schema for Internet Fax (V2) 257 5 January 259 3.2 Resolution 261 Feature tag name Legal values 262 ---------------- ------------ 263 dpi (>0) 264 dpi-xyratio (>0) 266 Reference: "Media Features for Display, Print, and Fax" [3], and 267 this document appendix A. 269 If 'dpi-xyratio' is present and not equal to 1 then the horizontal 270 resolution (x-axis) is indicated by the 'dpi' feature value, and 271 the vertical resolution (y-axis) is the value of 'dpi' divided by 272 'dpi-xyratio'. 274 For example, the basic Group 3 fax resolution of 200*100dpi might 275 be indicated as: 277 (& (dpi=200) (dpi-xyratio=200/100) ) 279 When describing resolutions for an MRC format document, the 280 complete set of usable resolutions is listed. However, there are 281 some restrictions on their use: (a) 100dpi resolution can be used 282 only with multi-level images, and (b) any multi-level image 283 resolution is required to be an integral sub-multiple of the 284 applicable mask resolution. 286 3.3 Media type 288 Feature tag name Legal values 289 ---------------- ------------ 290 ua-media screen 291 screen-paged 292 stationery 293 transparency 294 envelope 295 envelope-plain 296 continuous 298 Reference: "Media Features for Display, Print, and Fax" [3]. 300 NOTE: Where the recipient indicates specific support for 301 hard copy or soft copy media type, a sender of color 302 image data may wish to adjust the color components (e.g. 303 per the related rules of ITU recommendation T.42 [9]) to 304 improve rendered image quality on that medium. 306 Internet Draft Content Feature Schema for Internet Fax (V2) 307 5 January 309 3.4 Paper Size 311 Feature tag name Legal values 312 ---------------- ------------ 313 paper-size A4 314 A3 315 B4 316 letter 317 legal 319 Reference: "Media Features for Display, Print, and Fax" [3]. 321 3.5 Color capability 323 Feature tag name Legal values 324 ---------------- ------------ 325 color Binary (bi-level only) 326 Limited (a limited number of colors) 327 Mapped (palette or otherwise mapped color) 328 Grey (grey-scale only) 329 Full (full continuous-tone color) 331 Reference: "Media Features for Display, Print, and Fax" [3]. 333 The intention here is to give a broad indication of color handling 334 capabilities that might be used, for example, to select among a 335 small number of available data resources. 337 The value of this feature also gives an indication of the more 338 detailed color handling features that might be applicable (see next 339 section). 341 'Binary' indicates blank-and-white, or other bi-level capability. 342 No further qualifying feature tags are required. 344 'Limited' indicates a small number of distinct fixed colors, such 345 as might be provided by a highlight printer, pen plotter or limited 346 color display. The 'color-levels' tag should be used to indicate 347 the number of distinct colors available. 349 NOTE: No ability to indicate any specific or named color 350 is implied by this option. Some devices might use 351 different intensity levels rather than different hues for 352 distinction. 354 In the context of Internet fax, 'limited' is interpreted as one- 355 bit-per-color-sample (RGB, CMY or CMYK), depending on the color 356 space used. 358 Internet Draft Content Feature Schema for Internet Fax (V2) 359 5 January 361 'Mapped' indicates that pixel color values are mapped in some 362 specifiable way to a multi-component color space. The 'color- 363 levels' tag may be used to indicate the number of distinct colors 364 available; in its absence, sufficient levels to display a 365 photographic image should be assumed. 367 'Grey' indicates a continuous tone grey-scale capability. 369 'Full' indicates full continuous tone color capability. 371 For 'Mapped', 'Grey' and 'Full' color, additional feature tags 372 (section 3.6) may be used to further qualify the color 373 reproduction. 375 3.6 Color model 377 Feature tag name Legal values 378 ---------------- ------------ 379 color-levels (>2) 380 color-space Device-RGB (device RGB) 381 Device-CMY (device CMY) 382 Device-CMYK (device CMYK) 383 CIELAB (LAB per T.42 [9]) 384 (may be extended by further registrations) 385 color-illuminant (per ITU T.4 [x], E.6.7) 386 D50 387 D65 388 D75 389 SA 390 SC 391 F2 392 F7 393 F11 394 CTnnnn (see below) 395 CIELAB-L-depth (>0) 396 CIELAB-a-depth 397 CIELAB-b-depth 398 CIELAB-L-min 399 CIELAB-L-max 400 CIELAB-a-min 401 CIELAB-a-max 402 CIELAB-b-min 403 CIELAB-b-max 405 Reference: this document, appendix A. 407 Internet Draft Content Feature Schema for Internet Fax (V2) 408 5 January 410 The general model for image handling (both color and non-color) is 411 described here from a receiver's perspective; a similar model 412 operates in the reverse direction for a scan/send perspective: 414 raw bit pixel color physical 415 stream -(A)-> values -(B)-> values -(C)-> rendition 417 - "raw bit stream" is a stream of coded bits 419 (A) indicates image coding/decoding (MH,MR,MMR,JPEG,JBIG,etc.) 421 - "pixel values" are a single numeric value per picture element 422 that designates the color of that element. 424 (B) indicates pixel-to-color value mapping 426 - "color values" have a separate numeric value for each color 427 component (i.e. L*, a*, b* in the case of CIELAB indicated 428 above.) 430 (C) indicates how the color values are related to a physical 431 color. This involves interpretation of the color value with 432 respect to a color model (e.g. RGB, L*a*b*, CMY, CMYK) and a 433 color space (which is typically recipient-dependent). 435 - "physical rendition" is a color value physically realized on a 436 display, printer or other device. 438 There are many variables that can be applied at each stage of the 439 processing of a color image, and any may be critical to meaningful 440 handling of that image in some circumstances. In other 441 circumstances many of the variables may be implied (to some level 442 of approximation) in the application that uses them (e.g. color 443 images published on a Web page). 445 The color feature framework described here is intended to allow 446 capability description at a range of granularity: feature tags 447 which correspond to implied (or "don't care" or "unknown") feature 448 values may simply be omitted from a capability description. 450 Grey scale and bi-level images are handled within this framework as 451 a special case, having a 1-component color model. The following 452 features are used for describing color capabilities: 454 'color-levels' indicates the number of distinct values for each 455 picture element, and applies to all but bi-level images. For bi- 456 level images, a value of 2 is implied. 458 Internet Draft Content Feature Schema for Internet Fax (V2) 459 5 January 461 'color-space' is used mainly with 'Mapped' and 'Full', but could be 462 used with other modes if the exact color or color model used is 463 significant. Two kinds of color space can be distinguished: 464 device-dependent and calibrated. Device dependent spaces are named 465 here as 'Device-xxx', and are used to indicate a color space that 466 is defined by the receiving device. Calibrated color spaces 467 presume the existence of a rendering system that is calibrated with 468 respect to an indicated definition, and is capable of processing 469 the device-independent color information accordingly. 471 A color-handling receiver should indicate any appropriate device 472 color space capability in addition to any calibrated color spaces 473 that it may support. A calibrated color space should be used when 474 precise color matching is required in the absence of specific 475 knowledge of the receiving system. 477 NOTE: In practice, although they appear to be separate 478 concepts, the color model and color space cannot be 479 separated. In the final analysis, a color model (RGB, 480 CMY, etc.) must be defined with respect to some color 481 space. 483 'color-illuminant' indicates a CIE illuminant, using the same 484 general form that is used for this purpose by Group 3 fax (as 485 defined in ITU T.4 [13], section E.6.7). When the illuminant is 486 specified by its color temperature, the token string 'CTnnnn' is 487 used, where 'nnnn' is a decimal number that is the color 488 temperature in kelvins; e.g. CT7500 indicates an illuminant color 489 temperature of 7500K. 491 NOTE: ITU T.4 indicates a binary representation for color 492 temperature values. 494 In practice, much of the illuminant detail given here 495 will probably be unused by Internet fax. The only value 496 likely to be specified is 'D50', which is the default 497 color illuminant for Group 3 fax. 499 'CIELAB-L-depth', 'CIELAB-a-depth' and 'CIELAB-b-depth' indicate 500 the number of different values that are possible for the L*, a* and 501 b* color components respectively, and are significant only when 502 colors are represented in a CIELAB color space. These features 503 would be used with palletized color, or with full color where each 504 color component has a different number of possible values. 506 Internet Draft Content Feature Schema for Internet Fax (V2) 507 5 January 509 Color depth values relate to the representation of colour values 510 rather than the resolution of a scanning or rendering device. 511 Thus, if 256 different L-component values can be represented then 512 the assertion (CIELAB-L-depth<=256) is used, even if a receiving 513 device can render only 100 distinct luminance values. (Color 514 rendering resolution is not covered by this memo.) 516 The 'CIELAB-x-min' and 'CIELAB-x-max' values indicate a color gamut 517 (i.e. a range of color values that are used or may be rendered). A 518 gamut may be indicated in terms of the CIELAB color space even when 519 colors are represented in some other space. 521 3.7 Image coding 523 Feature tag name Legal values 524 ---------------- ------------ 525 image-file- TIFF 526 structure TIFF-limited 527 TIFF-minimal 528 TIFF-MRC 529 TIFF-MRC-limited 530 (may be extended by further registrations) 531 image-coding MH 532 MR 533 MMR 534 JBIG 535 JPEG 536 (may be extended by further registrations) 537 image-coding- JBIG-T85 (bi-level, per ITU T.85) 538 constraint JBIG-T43 (multi-level, per ITU T.43) 539 JPEG-T4E (per ITU T.4, Annex E) 540 (may be extended by further registrations) 541 JBIG-stripe-size 542 image-interleave Stripe 543 Plane 544 color-subsampling "1:1:1" (no color subsampling) 545 "4:1:1" (4:1:1 color subsampling) 547 Reference: this document, appendix A. 549 'image-file-structure' defines how the coded image data is wrapped 550 and formatted. The following options are defined here: 552 o 'TIFF' indicates image data enclosed and tagged using TIFF 553 structures described in Adobe's definition of TIFF [20]. 555 o 'TIFF-limited' indicates image data structured using TIFF, but 556 with the limitations on the placement of Image File Descriptors 557 (IFDs) indicated in section 4.4.6 of RFC 2301 [7]. 559 Internet Draft Content Feature Schema for Internet Fax (V2) 560 5 January 562 o 'TIFF-minimal' indicates a TIFF image format that meets the IFD 563 placement, byte ordering and bit ordering requirements of the 564 "minimal black and white mode" described in section 3.5 of RFC 565 2301 [7], also known as TIFF-S. 567 o 'TIFF-MRC' uses a TIFF image structure [20] augmented with a sub- 568 IFD structure, described for the "Mixed Raster Content mode" in 569 section 8.1.2 of RFC 2301 [7], also known as TIFF-M. This 570 provides a file structure to contain composite images constructed 571 using the MRC model described in T.44 [15] (see tag 'MRC-mode'). 573 o 'TIFF-MRC-limited' is the same as 'TIFF-MRC', except that the 574 primary IFD (i.e. top-level IFDs, as opposed to sub-IFDs) 575 placement is constrained in the same way as 'TIFF-limited'. 577 'image-coding' describes how raw image data is compressed and coded 578 as a sequence of bits. These are generic tags that may apply to a 579 range of file formats and usage environments. 581 'image-coding-constraint' describes how the raw image data coding 582 method is constrained to meet a particular operating environment. 583 Options defined here are JBIG and JPEG coding constraints that 584 apply in typical Group 3 fax environments. 586 The 'JBIG-stripe-size' feature may be used with JBIG image coding, 587 and indicates the number of scan lines in each stripe except the 588 last in an image. The legal constraints are: 590 (JBIG-stripe-size=128) 591 (JBIG-stripe-size>=0) 593 The latter being equivalent to no restriction. 595 NOTE: there are several image coding options here, and 596 not all are required in all circumstances. 598 Specification of the image-file-structure tag value alone 599 is not normally sufficient to describe the capabilities 600 of a recipient. A general rule is that sufficient detail 601 should be provided to exclude any unsupported features. 603 For extended Internet fax, image-file-structure and 604 image-coding should always be specified, together with 605 additional values described above as needed to clearly 606 indicate which feature tag values are supported and which 607 are not. (See also the examples in section 4.) 609 Internet Draft Content Feature Schema for Internet Fax (V2) 610 5 January 612 3.8 MRC mode 614 Feature tag name Legal values 615 ---------------- ------------ 616 MRC-mode (0..7) (per ITU T.44 [15]) 617 MRC-max-stripe-size 619 Reference: this document, appendix A. 621 The 'MRC-mode' feature is used to indicate the availability of MRC 622 (mixed raster content) image format capability. A zero value 623 indicates MRC is not available, a non-zero value indicates the 624 maximum available MRC mode number. 626 An MRC formatted document is actually a collection of several 627 images, each of which is described by a separate feature 628 collection. An MRC-capable receiver is presumed to be capable of 629 accepting any combination of contained images that conform to both 630 the MRC construction rules and the image-coding capabilities 631 declared elsewhere. 633 Within an MRC-formatted document, multi-level coders are used for 634 foreground and background images (i.e. odd-numbered layers: 1, 3, 635 5, etc.) and bi-level coders are used for mask layers (i.e. even 636 numbered layers 2, 4, 6, etc.). MRC format also imposes 637 constraints on the resolutions that can be used. 639 The 'MRC-max-stripe-size' feature may be used with MRC coding, and 640 indicates the maximum number of scan lines in each MRC stripe. The 641 legal constraints are: 643 (MRC-max-stripe-size<=256) 644 (MRC-max-stripe-size>=0) 646 These values indicate upper bounds on the stripe size. The actual 647 value may vary between stripes, and the actual size for each stripe 648 is indicated in the image data. 650 4. Examples 652 Some of the examples contain comments introduced by '--...'. These 653 are not part of the allowed capability description syntax. They 654 are included here to explain some of the constructs used. 656 The level of detail captured here reflects that used for capability 657 identification in Group 3 facsimile. 659 Internet Draft Content Feature Schema for Internet Fax (V2) 660 5 January 662 4.1 Simple mode Internet fax system 664 This example describes the capabilities of a typical simple mode 665 Internet fax system. Note that TIFF application S is required to 666 be supported by such a system. 668 (& (image-file-structure=TIFF-minimal) 669 (MRC-mode=0) 670 (color=Binary) 671 (image-coding=MH) (MRC-mode=0) 672 (| (& (dpi=204) (dpi-xyratio=[204/98,204/196]) ) 673 (& (dpi=200) (dpi-xyratio=[200/100,1]) ) ) 674 (size-x<=2150/254) 675 (paper-size=A4) 676 (ua-media=stationery) ) 678 4.2 High-end black-and-white Internet fax system 680 This would include support for B/W JBIG and be equivalent to what 681 is sometimes called "Super G3", except that Internet fax 682 functionality would be added. 684 (& (image-file-structure=TIFF) 685 (MRC-mode=0) 686 (color=Binary) 687 (| (& (dpi=204) (dpi-xyratio=[204/98,204/196]) ) 688 (& (dpi=200) (dpi-xyratio=[200/100,1]) ) 689 (& (dpi=300) (dpi-xyratio=1) ) ) 690 (| (image-coding=[MH,MR,MMR]) 691 (& (image-coding=JBIG) 692 (image-coding-constraint=JBIG-T85) 693 (JBIG-stripe-size=128) ) ) 694 (size-x<=2150/254) 695 (paper-size=[letter,A4,B4]) ) 696 (ua-media=stationery) ) 698 Internet Draft Content Feature Schema for Internet Fax (V2) 699 5 January 701 4.3 Grey-scale Internet fax system 703 This is the previous example extended to handle grey scale multi- 704 level images. In keeping with Group 3 fax, this example requires 705 equal x- and y- resolutions for a multi-level image. 707 (& (image-file-structure=TIFF) 708 (MRC-mode=0) 709 (| (& (color=Binary) 710 (| (image-coding=[MH,MR,MMR]) 711 (& (image-coding=JBIG) 712 (image-coding-constraint=JBIG-T85) 713 (JBIG-stripe-size=128) ) ) 714 (| (& (dpi=204) (dpi-xyratio=[204/98,204/196]) ) 715 (& (dpi=200) (dpi-xyratio=[200/100,1]) ) 716 (& (dpi=300) (dpi-xyratio=1) ) ) 717 (& (color=Grey) 718 (color-levels<=256) 719 (color-space-CIELAB) 720 (color-illuminant=D50) 721 (CIELAB-L-min>=0) 722 (CIELAB-L-max<=100) 723 (| (& (image-coding=JPEG) 724 (image-coding-constraint=JPEG-T4E) ) 725 (& (image-coding=JBIG) 726 (image-coding-constraint=JBIG-T43) 727 (JBIG-stripe-size=128) 728 (image-interleave=stripe) ) ) 729 (dpi=[100,200,300]) (dpi-xyratio=1) ) ) 730 (size-x<=2150/254) 731 (paper-size=[letter,A4,B4]) ) 732 (ua-media=stationery) ) 734 Internet Draft Content Feature Schema for Internet Fax (V2) 735 5 January 737 4.4 Full-color Internet fax system (JPEG only) 739 This adds 24-bit full-color to the previous example. 741 (& (image-file-structure=TIFF) 742 (MRC-mode=0) 743 (| (& (color=Binary) 744 (image-coding=[MH,MR,MMR]) 745 (| (& (dpi=204) (dpi-xyratio=[204/98,204/196]) ) 746 (& (dpi=200) (dpi-xyratio=[200/100,1]) ) 747 (& (dpi=300) (dpi-xyratio=1) ) ) ) 748 (& (color=grey) 749 (image-coding=JPEG) 750 (image-coding-constraint=JPEG-T4E) 751 (color-levels<=256) 752 (color-space=CIELAB) 753 (color-illuminant=D50) 754 (CIELAB-L-min>=0) 755 (CIELAB-L-max<=100) 756 (dpi=[100,200,300]) (dpi-xyratio=1) ) 757 (& (color=full) 758 (image-coding=JPEG) 759 (image-coding-constraint=JPEG-T4E) 760 (color-subsampling=["1:1:1","4:1:1"]) 761 (color-levels<=16777216) 762 (color-space=CIELAB) 763 (color-illuminant=D50) 764 (CIELAB-L-min>=0) 765 (CIELAB-L-max<=100) 766 (CIELAB-a-min>=-85) 767 (CIELAB-a-max<=85) 768 (CIELAB-b-min>=-75) 769 (CIELAB-b-max<=125) 770 (dpi=[100,200,300]) (dpi-xyratio=1) ) ) 771 (size-x<=2150/254) 772 (paper-size=[letter,A4,B4]) ) 773 (ua-media=stationery) ) 775 Internet Draft Content Feature Schema for Internet Fax (V2) 776 5 January 778 4.5 Full-color Internet fax system (JPEG and JBIG) 780 This adds limited CMY(K), RGB and 16-bit mapped color using JBIG 781 coding to the previous example. 783 (& (image-file-structure=TIFF) 784 (MRC-mode=0) 785 (| (& (color=Binary) 786 (| (image-coding=[MH,MR,MMR]) 787 (& (image-coding=JBIG) 788 (image-coding-constraint=JBIG-T85) 789 (JBIG-stripe-size=128) ) ) 790 (| (& (dpi=204) (dpi-xyratio=[204/98,204/196]) ) 791 (& (dpi=200) (dpi-xyratio=[200/100,1]) ) 792 (& (dpi=300) (dpi-xyratio=1) ) ) ) 793 (& (color=Limited) 794 (image-coding=JBIG) 795 (image-coding-constraint=JBIG-T43) 796 (JBIG-stripe-size=128) 797 (image-interleave=stripe) 798 (| (& (color-space=[Device-RGB,Device-CMY]) 799 (color-levels<=8) ) 800 (& (color-space=Device-CMYK) 801 (color-levels<=16) ) ) 802 (dpi=[100,200,300]) (dpi-xyratio=1) ) 803 (& (color=Mapped) 804 (image-coding=JBIG) 805 (image-coding-constraint=JBIG-T43) 806 (JBIG-stripe-size=128) 807 (image-interleave=stripe) 808 (color-levels<=65536) 809 (color-space=CIELAB) 810 (color-illuminant=D50) 811 (CIELAB-L-min>=0) 812 (CIELAB-L-max<=100) 813 (CIELAB-a-min>=-85) 814 (CIELAB-a-max<=85) 815 (CIELAB-b-min>=-75) 816 (CIELAB-b-max<=125) 817 (dpi=[100,200,300]) (dpi-xyratio=1) ) 818 (& (color=grey) 819 (| (& (image-coding=JPEG) 820 (image-coding-constraint=JPEG-T4E) ) 821 (& (image-coding=JBIG) 822 (image-coding-constraint=JBIG-T43) 823 (JBIG-stripe-size=128) 824 (image-interleave=stripe) ) ) 825 (color-levels<=256) 826 (color-space=CIELAB) 827 (color-illuminant=D50) 829 Internet Draft Content Feature Schema for Internet Fax (V2) 830 5 January 832 (CIELAB-L-min>=0) 833 (CIELAB-L-max<=100) 834 (dpi=[100,200,300]) (dpi-xyratio=1) ) 835 (& (color=full) 836 (| (& (image-coding=JPEG) 837 (image-coding-constraint=JPEG-T4E) 838 (color-subsampling=["1:1:1","4:1:1"]) ) 839 (& (image-coding=JBIG) 840 (image-coding-constraint=JBIG-T43) 841 (JBIG-stripe-size=128) 842 (image-interleave=stripe) ) ) 843 (color-levels<=16777216) 844 (color-space=CIELAB) 845 (color-illuminant=D50) 846 (CIELAB-L-min>=0) 847 (CIELAB-L-max<=100) 848 (CIELAB-a-min>=-85) 849 (CIELAB-a-max<=85) 850 (CIELAB-b-min>=-75) 851 (CIELAB-b-max<=125) 852 (dpi=[100,200,300]) (dpi-xyratio=1) ) ) 853 (size-x<=2150/254) 854 (paper-size=[letter,A4,B4]) ) 855 (ua-media=stationery) ) 857 4.6 Full-color Internet fax system (MRC) 859 This adds MRC image structures to the previous example. 861 (& (image-file-structure=TIFF-MRC) 862 (MRC-mode<=1) (MRC-max-stripe-size>=0) 863 (| (& (color=binary) 864 (| (image-coding=[MH,MR,MMR]) 865 (& (image-coding=JBIG) 866 (image-coding-constraint=JBIG-T85) 867 (JBIG-stripe-size=128) ) ) 868 (| (& (dpi=204) (dpi-xyratio=[204/98,204/196]) ) 869 (& (dpi=200) (dpi-xyratio=[200/100,1]) ) 870 (& (dpi=[300,400]) (dpi-xyratio=1) ) ) ) 871 (& (color=limited) 872 (| (& (color-space=[Device-RGB,Device-CMY]) 873 (color-levels<=8) ) ) 874 (| (& (color-space=Device-CMYK) 875 (color-levels<=16) ) ) 876 (image-coding=JBIG) 877 (image-coding-constraint=JBIG-T43) 878 (JBIG-stripe-size=128) 879 (image-interleave=stripe) 880 (dpi=[100,200,300,400]) (dpi-xyratio=1) ) 881 (& (color=mapped) 883 Internet Draft Content Feature Schema for Internet Fax (V2) 884 5 January 886 (color-levels<=65536) 887 (image-coding=JBIG) 888 (image-coding-constraint=JBIG-T43) 889 (JBIG-stripe-size=128) 890 (image-interleave=stripe) 891 (color-space=CIELAB) 892 (CIELAB-L-min>=0) 893 (CIELAB-L-max<=100) 894 (CIELAB-a-min>=-85) 895 (CIELAB-a-max<=85) 896 (CIELAB-b-min>=-75) 897 (CIELAB-b-max<=125) ) ) 898 (color-illuminant=D50) 899 (dpi=[100,200,300,400]) (dpi-xyratio=1) ) 900 (& (color=grey) 901 (| (& (image-coding=JPEG) 902 (image-coding-constraint=JPEG-T4E) ) 903 (& (image-coding=JBIG) 904 (image-coding-constraint=JBIG-T43) 905 (JBIG-stripe-size=128) 906 (image-interleave=stripe) ) ) 907 (color-space=CIELAB) 908 (color-levels<=256) 909 (color-illuminant=D50) 910 (CIELAB-L-min>=0) 911 (CIELAB-L-max<=100) 912 (dpi=[100,200,300,400]) (dpi-xyratio=1) ) 913 (& (color=full) 914 (| (& (image-coding=JPEG) 915 (image-coding-constraint=JPEG-T4E) 916 (color-subsampling=["1:1:1","4:1:1"]) ) 917 (& (image-coding=JBIG) 918 (image-coding-constraint=JBIG-T43) 919 (JBIG-stripe-size=128) 920 (image-interleave=stripe) ) ) 921 (color-levels<=16777216) 922 (color-space=CIELAB) 923 (color-illuminant=D50) 924 (CIELAB-L-min>=0) 925 (CIELAB-L-max<=100) 926 (CIELAB-a-min>=-85) 927 (CIELAB-a-max<=85) 928 (CIELAB-b-min>=-75) 929 (CIELAB-b-max<=125) 930 (dpi=[100,200,300,400]) (dpi-xyratio=1) ) ) 931 (size-x<=2550/254) 932 (Paper-size=[Letter,A4,B4]) 933 (ua-media=stationery) ) 935 Internet Draft Content Feature Schema for Internet Fax (V2) 936 5 January 938 4.7 Sender and receiver feature matching 940 This example considers sending a document to an enhanced black-and- 941 white fax system with the following receiver capabilities: 943 (& (| (& (dpi=200) (dpi-xyatio=200/100) ) 944 (& (dpi=200) (dpi-xyratio=1) ) 945 (& (dpi=300) (dpi-xyratio=1) ) 946 (& (dpi=400) (dpi-xyratio=1) ) ) 947 (color=Binary) 948 (| (& (paper-size=A4) (ua-media=[stationery,transparency]) ) 949 (& (paper-size=B4) (ua-media=continuous) ) ) 950 (image-coding=[MH,MR,JBIG]) ) 952 Turning to the document itself, assume it is available to the 953 sender in three possible formats, A4 high resolution, B4 low 954 resolution and A4 high resolution color, described by: 956 (& (dpi=300) (dpi-xyratio=1) 957 (color=Binary) 958 (paper-size=A4) 959 (image-coding=[MMR,JBIG]) ) 961 (& (dpi=200) (dpi-xyratio=200/100) 962 (color=Binary) 963 (paper-size=B4) 964 (image-coding=[MH,MR]) ) 966 (& (dpi=300) (dpi-xyratio=1) 967 (color=Mapped) (color-levels<=256) 968 (paper-size=A4) 969 (image-coding=JPEG) ) 971 These three image formats can be combined into a composite 972 capability statement by a logical-OR operation (to describe 973 format-1 OR format-2 OR format-3): 975 (| (& (dpi=300) (dpi-xyratio=1) 976 (color=Binary) 977 (paper-size=A4) 978 (image-coding=[MMR,JBIG]) ) 979 (& (dpi=200) (dpi-xyratio=200/100) 980 (color=Binary) 981 (paper-size=B4) 982 (image-coding=[MH,MR]) ) 983 (& (dpi=300) (dpi-xyratio=1) 984 (color=Mapped) (color-levels=42) 985 (paper-size=A4) 986 (image-coding=JPEG) ) ) 988 Internet Draft Content Feature Schema for Internet Fax (V2) 989 5 January 991 This could be simplified, but there is little gain in doing so at 992 this point. 994 The composite document description can be matched with the receiver 995 capability description, according to the rules in [2], to yield the 996 result: 998 (| (& (dpi=300) (dpi-xyratio=1) 999 (color=Binary) 1000 (paper-size=A4) 1001 (ua-media=[stationery,transparency]) 1002 (image-coding=JBIG) ) 1003 (& (dpi=200) (dpi-xyratio=200/100) 1004 (color=Binary) 1005 (paper-size=B4) 1006 (ua-media=continuous) 1007 (image-coding=[MH,MR]) ) ) 1009 Points to note about the feature matching process: 1011 o The color document option is eliminated because the receiver 1012 cannot handle either color (indicated by '(color=Mapped)') or 1013 JPEG coding (indicated by '(image-coding=JPEG)'). 1015 o The high resolution version of the document with '(dpi=300)' must 1016 be send using '(image-coding=JBIG)' because this is the only 1017 available coding of the image data that the receiver can use for 1018 high resolution documents. (The available 300dpi document 1019 codings here are MMR and JBIG, and the receiver capabilities are 1020 MH, MR and JBIG.) 1022 o The low-resolution version of the document can be sent with 1023 either MH or MR coding as the receiver can deal with either of 1024 these for low resolution documents. 1026 o The high resolution variant of the document is available only for 1027 A4, so that is the paper-size used in that case. Similarly the 1028 low resolution version is sent for B4 paper. 1030 o Even though the sender may not understand the 'ua-media' feature 1031 tag, and does not mention it, the matching rules preserve the 1032 constraint that the B4 document is rendered with 1033 '(ua-media=continuous)', and the A4 document may be rendered with 1034 '(ua-media=[stationery,transparency])'. 1036 Finally, note that when matching an MRC document description, the 1037 description of each component sub-image must match the capabilities 1038 of the intended receiver. 1040 Internet Draft Content Feature Schema for Internet Fax (V2) 1041 5 January 1043 5. IANA considerations 1045 Appendix A of this document repeats the descriptions of feature 1046 tags introduced by RFC 2531 [22], with some small revisions. These 1047 have been registered in the "IETF tree", according to the procedure 1048 described in section 3.1.1 of "Media Feature Tag Registration 1049 Procedure" [1] (i.e. these feature tags are subject to the "IETF 1050 Consensus" policies described in RFC 2434 [21]). 1052 Appendix section A.5 introduces one new feature tag (color- 1053 illuminant) to be registered according to the same procedure. An 1054 ASN.1 identifier should be assigned for this new tag and replaced 1055 in the body of the registration. 1057 6. Security considerations 1059 The points raised below are in addition to the general security 1060 considerations for extended Internet fax [5], and others discussed 1061 in [2,8,11,12,13] 1063 6.1 Capability descriptions and mechanisms 1065 Negotiation mechanisms reveal information about one party to other 1066 parties. This may raise privacy concerns, and may allow a 1067 malicious party to make better guesses about the presence of 1068 specific security holes. 1070 Most of these concerns pertain to capability information getting 1071 into the hands of someone who may abuse it. This document 1072 specifies capabilities that help a sender to determine what image 1073 characteristics can be processed by the recipient, not mechanisms 1074 for their publication. Implementers and users should take care 1075 that the mechanisms employed ensure that capabilities are revealed 1076 only to appropriate persons, systems and agents. 1078 6.2 Specific threats 1080 1. Unsolicited bulk mail: if it is known that a recipient can 1081 process certain types of images, they may be targeted by bulk 1082 mailers that want to send such images. 1084 7. Acknowledgements 1086 The authors gratefully acknowledge the contributions of the 1087 following persons who commented on earlier versions of this memo: 1088 James Rafferty, Dan Wing, Robert Buckley, Mr Ryuji Iwazaki. The 1089 following contributed ideas upon which some of the features 1090 described here have been based: Larry Masinter, Al Gilman, Koen 1091 Holtman. 1093 Internet Draft Content Feature Schema for Internet Fax (V2) 1094 5 January 1096 8. References 1098 [1] RFC 2506, "Media Feature Tag Registration Procedure" 1099 Koen Holtman, TUE 1100 Andrew Mutz, Hewlett-Packard 1101 Ted Hardie, NASA 1102 March 1999. 1104 [2] RFC 2533, "A syntax for describing media feature sets" 1105 Graham Klyne, 5GM/Content Technologies 1106 March 1999. 1108 [3] RFC 2534, "Media Features for Display, Print, and Fax" 1109 Larry Masinter, Xerox PARC 1110 Koen Holtman, TUE 1111 Andrew Mutz, Hewlett-Packard 1112 Dan Wing, Cisco Systems 1113 March 1999. 1115 [4] "Internet fax feature mapping from Group 3 fax" 1116 Lloyd McIntyre, Xerox Corporation 1117 Graham Klyne, Content Technologies 1118 Internet draft: 1119 Work in progress, January 2000. 1121 [5] RFC 2532, "Extended Facsimile Using Internet Mail" 1122 Larry Masinter, Xerox Corporation 1123 Dan Wing, Cisco Systems 1124 March 1999. 1126 [6] "Procedures for document facsimile transmission in the general 1127 switched telephone network" 1128 ITU-T Recommendation T.30 (1996) 1129 International Telecommunications Union 1130 July 1996 1132 [7] RFC 2301, "File format for Internet fax" 1133 L. McIntyre, 1134 R. Buckley, 1135 D. Venable, Xerox Corporation 1136 S. Zilles, Adobe Systems, Inc. 1137 G. Parsons, Northern Telecom 1138 J. Rafferty, Human Communications 1139 March 1998. 1141 Internet Draft Content Feature Schema for Internet Fax (V2) 1142 5 January 1144 [8] RFC 2305, "A Simple Mode of Facsimile Using Internet Mail" 1145 K. Toyoda 1146 H. Ohno 1147 J. Murai, WIDE Project 1148 D. Wing, Cisco Systems 1149 March 1998. 1151 [9] "Continuous-tone color representation method for facsimile" 1152 ITU-T Recommendation T.42 (1996) 1153 International Telecommunications Union 1154 (Covers custom illuminant, gamut) 1156 [10] "Colour and gray-scale image representation using lossless coding 1157 scheme for facsimile" 1158 ITU-T Recommendation T.43 (1997) 1159 International Telecommunications Union. 1160 (Covers JBIG for colour/grey images) 1162 [11] (Reference deleted) 1164 [12] RFC 2703, "Protocol-independent Content Negotiation Framework" 1165 Graham Klyne, 5GM/Content Technologies 1166 September 1999. 1168 [13] "Standardization of Group 3 facsimile terminals for document 1169 transmission" 1170 ITU-T Recommendation T.4 (1996) 1171 International Telecommunications Union 1172 (Covers basic fax coding formats: MH, MR) 1174 [14] "Facsimile coding schemes and coding control functions for 1175 Group 4 facsimile apparatus" 1176 ITU Recommendation T.6 1177 International Telecommunications Union 1178 (Commonly referred to as the MMR standard; covers extended 2-D 1179 fax coding format) 1181 [15] "Mixed Raster Content (MRC)" 1182 ITU-T Recommendation T.44 1183 International Telecommunications Union 1185 [16] "Information technology - Digital compression and coding of 1186 continuous-tone still image - Requirements and guidelines" 1187 ITU-T Recommendation T.81 (1992) | ISO/IEC 10918-1:1993 1188 International Telecommunications Union 1189 (Commonly referred to as JPEG standard) 1191 Internet Draft Content Feature Schema for Internet Fax (V2) 1192 5 January 1194 [17] "Information technology - Coded representation of picture and 1195 audio information - Progressive bi-level image compression" 1196 ITU-T Recommendation T.82 (1993) | ISO/IEC 11544:1993 1197 International Telecommunications Union 1198 (Commonly referred to as JBIG1 standard) 1200 [18] "Application profile for Recommendation T.82 - Progressive bi- 1201 level image compression (JBIG1 coding scheme for facsimile 1202 apparatus)" 1203 ITU-T Recommendation T.85 (1995) 1204 International Telecommunications Union 1205 (Covers bi-level JBIG) 1207 [19] "Colorimeter, 2nd ed." 1208 CIE Publication No. 15.2 1209 1986. 1210 (Defines CIELAB color space; use with fax is further constrained 1211 by T.42 [9].) 1213 [20] Tag Image File Format, Revision 6.0 1214 Adobe Developers Association 1215 1217 June 1992 1219 [21] RFC 2434, "Guidelines for Writing an IANA Considerations Section 1220 in RFCs" 1221 T. Narten, IBM 1222 H. Alvestrand, Maxware 1223 October 1998. 1225 [22] RFC 2531, "Content feature schema for Internet fax" 1226 Graham Klyne, 5GM/Content Technologies 1227 Lloyd McIntyre, Xerox Corporation 1228 March 1999. 1230 9. Authors' addresses 1232 Graham Klyne 1233 Content Technologies Ltd. 1234 1220 Parkview, 1235 Arlington Business Park 1236 Theale 1237 Reading, RG7 4SA 1238 United Kingdom. 1239 Telephone: +44 118 930 1300 1240 Facsimile: +44 118 930 1301 1241 E-mail: GK@ACM.ORG 1243 Internet Draft Content Feature Schema for Internet Fax (V2) 1244 5 January 1246 Lloyd McIntyre 1247 Xerox Corporation 1248 Mailstop PAHV-121 1249 3400 Hillview Ave. 1250 Palo Alto, CA 94304 USA 1251 Telephone: +1-650-813-6762 1252 Facsimile: +1-650-845-2340 1253 E-mail: Lloyd.McIntyre@pahv.xerox.com 1255 Internet Draft Content Feature Schema for Internet Fax (V2) 1256 5 January 1258 Appendix A: Feature registrations 1260 A.1 Image size 1262 - Media Feature tag name(s): 1264 size-x 1265 size-y 1267 - ASN.1 identifiers associated with these feature tags: 1269 size-x: 1.3.6.1.8.1.7 1270 size-y: 1.3.6.1.8.1.8 1272 - Summary of the media features indicated: 1274 These feature tags indicate the size of a displayed, printed 1275 or otherwise rendered document image; they indicate 1276 horizontal (size-x) and vertical (size-y) dimensions. 1278 The unit of measure is inches (to be consistent with the 1279 measure of resolution defined by the feature tag 'dpi'). 1281 Where the actual size is available in millimetres, a 1282 conversion factor of 10/254 may be applied to yield an exact 1283 inch-based value. 1285 - Values appropriate for use with these feature tags: 1287 Rational (>0) 1289 - The feature tag is intended primarily for use in the following 1290 applications, protocols, services, or negotiation mechanisms: 1292 Print and display applications where different media choices 1293 will be made depending on the size of the recipient device. 1295 - Examples of typical use: 1297 This example describes the maximum scanned image width and 1298 height for Group 3 fax: 215x297 mm (8.46x11.69 inches): 1300 (size-x<=2150/254) 1301 (size-y<=2970/254) 1303 Internet Draft Content Feature Schema for Internet Fax (V2) 1304 5 January 1306 - Related standards or documents: 1308 The memo "Media Features for Display, Print, and Fax" [3] 1309 describes features (pix-x, pix-y) for measuring document size 1310 in pixels. 1312 Fax applications should declare physical dimensions using the 1313 features defined here. 1315 - Considerations particular to use in individual applications, 1316 protocols, services, or negotiation mechanisms: 1318 Where no physical size is known or available, but a pixel size 1319 is known, a notional size should be declared based upon known 1320 pixel dimensions and a notional resolution of (say) 100dpi 1322 For example, to describe a 640x480 pixel display: 1324 (& (size-x<=640/100) (size-y<=480/100) (dpi=100) ) 1326 The notional 100dpi resolution is used as it represents a 1327 fairly typical resolution for a pixel-limited display. 1328 Reducing the rational numbers to canonical form gives the 1329 following equivalent expression: 1331 (& (size-x<=32/5) (size-y<=24/5) (dpi=100) ) 1333 - Interoperability considerations: 1335 For interoperability with other (non-fax) applications that 1336 use only pixel-based measurements, pixel dimensions (pix-x, 1337 pix-y) may be declared in addition to physical measurements. 1339 - Related feature tags: 1341 pix-x [3] 1342 pix-y [3] 1343 dpi [3] 1344 dpi-xyratio [this document] 1346 - Intended usage: 1348 Common 1350 - Author/Change controller: 1352 IETF 1354 Internet Draft Content Feature Schema for Internet Fax (V2) 1355 5 January 1357 A.2 Resolution aspect ratio 1359 - Media Feature tag name(s): 1361 dpi-xyratio 1363 - ASN.1 identifier associated with this feature tag: 1365 1.3.6.1.8.1.9 1367 - Summary of the media features indicated: 1369 This feature is used to indicate differential horizontal and 1370 vertical resolution capability. In the absence of this 1371 feature, horizontal and vertical resolutions are presumed to 1372 be the same. 1374 When this feature tag is specified, any declared resolution 1375 (dpi) is presumed to apply to the horizontal axis, and the 1376 vertical resolution is obtained by dividing that declared 1377 resolution by the resolution ratio. 1379 The value of this feature is a pure number, since it 1380 represents the ratio of two resolution values. 1382 - Values appropriate for use with this feature tag: 1384 Rational (>0) 1386 - The feature tag is intended primarily for use in the following 1387 applications, protocols, services, or negotiation mechanisms: 1389 Internet fax, and other print or display applications that 1390 must handle differential horizontal and vertical resolution 1391 values. 1393 - Examples of typical use: 1395 The following example describes a fax resolution of 204 dpi 1396 horizontally by 391 dpi vertically: 1398 (& (dpi=204) (dpi-xyratio=204/391) ) 1400 - Related standards or documents: 1402 The memo "Media Features for Display, Print, and Fax" [3] 1403 describes a feature (dpi) for measuring document resolution. 1405 Internet Draft Content Feature Schema for Internet Fax (V2) 1406 5 January 1408 - Interoperability considerations: 1410 When interoperating with an application that does not 1411 recognize the differential resolution feature, resolution 1412 matching may be performed on the basis of the horizontal 1413 resolution only, so aspect ratio information may be lost. 1415 - Related feature tags: 1417 dpi [3] 1418 size-x [this document] 1419 size-y [this document] 1421 - Intended usage: 1423 Internet fax 1425 - Author/Change controller: 1427 IETF 1429 Internet Draft Content Feature Schema for Internet Fax (V2) 1430 5 January 1432 A.3 Color levels 1434 - Media Feature tag name(s): 1436 color-levels 1438 - ASN.1 identifier associated with this feature tag: 1440 1.3.6.1.8.1.10 1442 - Summary of the media features indicated: 1444 This feature tag is used to indicate a number of different 1445 image data pixel color values. 1447 When mapped (palletized) color is used, this is generally 1448 different from the number of different colors that can be 1449 represented through the color mapping function. 1451 This feature tag is used in conjunction with a 'color' feature 1452 having a value other than 'Binary'. 1454 - Values appropriate for use with this feature tag: 1456 Integer (>=2) 1458 - The feature tag is intended primarily for use in the following 1459 applications, protocols, services, or negotiation mechanisms: 1461 Color image printing or display applications where the data 1462 resource used may depend upon color handling capabilities of 1463 the recipient. 1465 - Examples of typical use: 1467 To describe recipient capabilities: 1468 (& (color=limited) (color-levels<=6) ) 1469 (& (color=grey) (color-levels<=64) ) 1470 (& (color=mapped) (color-levels<=240) ) 1471 (& (color=full) (color-levels<=16777216) ) 1473 To describe capabilities used by a document: 1474 (& (color=limited) (color-levels=4) ) 1475 (& (color=grey) (color-levels=48) ) 1476 (& (color=mapped) (color-levels=100) ) 1477 (& (color=full) (color-levels=32768) ) 1479 Internet Draft Content Feature Schema for Internet Fax (V2) 1480 5 January 1482 - Related standards or documents: 1484 The memo "Media Features for Display, Print, and Fax" [3] 1485 describes a feature (color) for indicating basic color 1486 capabilities. 1488 - Interoperability considerations: 1490 The actual number of color values used by a document does not, 1491 in general, exactly match the number that can be handled by a 1492 recipient. To achieve a feature match, at least one must be 1493 declared as an inequality. 1495 It is recommended that a recipient declares the number of 1496 color values that it can handle as an inequality (<=), and a 1497 data resource declares the number of colors that it uses with 1498 an equality, as shown in the examples above. 1500 - Security considerations: 1502 - Privacy concerns, related to exposure of personal information: 1503 Where feature matching is used to select content applicable 1504 to the physical abilities of a user, unusual values for this 1505 feature tag might give an indication of a user's restricted 1506 abilities. 1508 - Related feature tags: 1510 color [3] 1511 color-space [this document] 1513 - Intended usage: 1515 Internet fax 1516 Color image scanning/rendering applications 1518 - Author/Change controller: 1520 IETF 1522 Internet Draft Content Feature Schema for Internet Fax (V2) 1523 5 January 1525 A.4 Color space 1527 - Media Feature tag name(s): 1529 color-space 1531 - ASN.1 identifier associated with this feature tag: 1533 1.3.6.1.8.1.11 1535 - Summary of the media features indicated: 1537 This feature indicates a color space. 1539 A color space value provides two types of information: 1540 o the color model used to represent a color value, including 1541 the number of color components 1542 o a mapping between color values and their physical 1543 realizations 1545 Device color space values are defined for applications where 1546 the general color representation used is significant, but 1547 exact color rendering is left to the device used. Device 1548 color spaces defined here have values of the form 'Device- 1549 xxx'. 1551 Calibrated color space values are provided for use with a 1552 rendering system that is calibrated with respect to some 1553 indicated definition, and capable of processing device- 1554 independent color information accordingly. 1556 - Values appropriate for use with this feature tag: 1558 Token 1560 Device color Device-RGB (device dependent RGB) 1561 spaces: Device-CMY (device dependent CMY) 1562 Device-CMYK (device dependent CMYK) 1564 Calibrated color CIELAB (per T.42 [9]) 1565 space: 1567 (may be extended by further registrations) 1569 'Color-space=CIELAB' indicates the CIE L*a*b* colour space, 1570 using CIED50 illuminant and its perfectly diffuse reflecting 1571 white point (per T.42 [9]). 1573 Internet Draft Content Feature Schema for Internet Fax (V2) 1574 5 January 1576 - The feature tag is intended primarily for use in the following 1577 applications, protocols, services, or negotiation mechanisms: 1579 Color image printing and display applications where the data 1580 resource used may depend upon color handling capabilities of 1581 the recipient. 1583 Scanning applications where the data transferred may depend 1584 upon the image generation capabilities of the originator. 1586 - Examples of typical use: 1588 To describe rendering or scanning capabilities: 1590 (color-space=[Device-RGB,CIELAB]) 1592 To describe capabilities assumed by a document for which 1593 approximate color reproduction is required: 1595 (color-space=Device-RGB) 1597 To describe capabilities assumed by a document for which exact 1598 color reproduction is required: 1600 (color-space=CIELAB) 1602 - Related standards or documents: 1604 CIELAB color space is defined in [19] 1606 CIELAB use for fax is described in ITU T.42 [9] 1608 - Interoperability considerations: 1610 A color-handling receiver should indicate at any appropriate 1611 device color space capability, in addition to any calibrated 1612 color spaces that it may support. 1614 Calibrated color spaces are intended to be used when precise 1615 color matching is required; otherwise, if applicable, a 1616 device color space (color-space=Device-xxx) should be 1617 indicated. 1619 Documents for which exact color matching is not important 1620 should indicate a device color space capability, if 1621 applicable. 1623 These principles allow sender/receiver feature matching to be 1624 achieved when exact color matching is not required. 1626 Internet Draft Content Feature Schema for Internet Fax (V2) 1627 5 January 1629 - Security considerations: 1631 - Privacy concerns, related to exposure of personal information: 1632 Where feature matching is used to select content applicable 1633 to the physical abilities of a user, unusual values for this 1634 feature tag might give an indication of a user's restricted 1635 abilities. 1637 - Denial of service concerns related to consequences of 1638 specifying incorrect values: 1639 Failure to indicate a generic color space capability for a 1640 device may lead to failure to match color space for an 1641 application or document that does not require an exact color 1642 match. 1644 - Related feature tags: 1646 color [3] 1648 - Related media types or data formats: 1650 TIFF-FX [7] 1652 - Intended usage: 1654 Internet fax 1655 Color image scanning/rendering applications 1657 - Author/Change controller: 1659 IETF 1661 Internet Draft Content Feature Schema for Internet Fax (V2) 1662 5 January 1664 A.5 CIELAB color illuminant 1666 - Media Feature tag name(s): 1668 color-illuminant 1670 - ASN.1 identifier associated with this feature tag: 1672 [[[New IANA-allocated value]]] 1674 - Summary of the media features indicated: 1676 This feature indicates a color illuminant. This has the 1677 effect of modifying the color space calibration to reflect the 1678 use of different sources of illumination. 1680 A color-illuminant value would normally be used only with a 1681 calibrated color space. 1683 - Values appropriate for use with this feature tag: 1685 Token 1687 CIELAB illuminant D50 1688 values: D65 1689 D75 1690 SA 1691 SC 1692 F2 1693 F7 1694 F11 1696 Defined by color CTnnnn where 'nnnn' is a decimal 1697 temperature: representation of the illuminant 1698 color temperature in kelvins. 1700 (may be extended by further registrations) 1702 NOTE: The default color illuminant for Group 3 fax is D50. 1704 - The feature tag is intended primarily for use in the following 1705 applications, protocols, services, or negotiation mechanisms: 1707 Color image printing and display applications where the data 1708 resource used may depend upon detailed color handling 1709 capabilities of the recipient. 1711 Scanning applications where the data transferred may depend 1712 upon the image generation capabilities of the originator. 1714 Internet Draft Content Feature Schema for Internet Fax (V2) 1715 5 January 1717 - Examples of typical use: 1719 To describe rendering or scanning capabilities, or to describe 1720 capabilities assumed by a document for which exact color 1721 handling capabilities are required: 1723 (& (color-space=CIELAB) (color-illuminant=D50) ) 1725 - Related standards or documents: 1727 CIELAB color illuminant representations are described in ITU 1728 T.4 [13], Annex E.6.7. 1730 - Interoperability considerations: 1732 A color-handling receiver that supports a calibrated color 1733 space should indicate any constraint on the illuminants it can 1734 handle. 1736 In the absence of a color-illuminant constraint, a receiver is 1737 presumed to accept and deal with any specified illuminant 1738 value. 1740 - Related feature tags: 1742 color [3] 1743 color-space [this document] 1745 - Related media types or data formats: 1747 TIFF-FX [7] 1749 - Intended usage: 1751 Internet fax 1752 Color image scanning/rendering applications 1754 - Author/Change controller: 1756 IETF 1758 Internet Draft Content Feature Schema for Internet Fax (V2) 1759 5 January 1761 A.6 CIELAB color depth 1763 - Media Feature tag name(s): 1765 CIELAB-L-depth 1766 CIELAB-a-depth 1767 CIELAB-b-depth 1769 - ASN.1 identifiers associated with these feature tags: 1771 CIELAB-L-depth: 1.3.6.1.8.1.12 1772 CIELAB-a-depth: 1.3.6.1.8.1.13 1773 CIELAB-b-depth: 1.3.6.1.8.1.14 1775 - Summary of the media features indicated: 1777 These feature tags indicate a color depth capability; i.e. 1778 the level of detail to which an individual CIELAB color 1779 component can be specified. They define the number of 1780 distinct values possible for each of the color components L*, 1781 a* and b*. 1783 Typically, this feature would be used with 'color=mapped', and 1784 possibly 'color=grey' or 'color=full', to indicate the number 1785 of distinct colors that can be represented. 1787 NOTE: this feature tag describes the number of values that 1788 can be represented for a color component, and does not 1789 necessarily indicate the number of distinct values that can 1790 be rendered or resolved by a system. 1792 - Values appropriate for use with these feature tags: 1794 Integer (>0) 1796 - These feature tags are intended primarily for use in the 1797 following applications, protocols, services, or negotiation 1798 mechanisms: 1800 Color image printing and display applications where the data 1801 resource used may depend upon color handling capabilities of 1802 the recipient. 1804 Scanning applications where the data transferred may depend 1805 upon the image generation capabilities of the originator. 1807 Internet Draft Content Feature Schema for Internet Fax (V2) 1808 5 January 1810 - Examples of typical use: 1812 To describe rendering or scanning capabilities: 1814 (& (color=mapped) (color-levels<=240) 1815 (CIELAB-L-depth<=128) 1816 (CIELAB-a-depth<=128) 1817 (CIELAB-b-depth<=128) ) 1818 (& (color=full) (color-levels<=16777216) 1819 (CIELAB-L-depth<=256) 1820 (CIELAB-a-depth<=128) 1821 (CIELAB-b-depth<=128) ) 1823 To describe capabilities assumed by a document: 1825 (& (color=mapped) (color-levels=200) 1826 (CIELAB-L-depth=32) 1827 (CIELAB-a-depth=32) 1828 (CIELAB-b-depth=32) ) 1829 (& (color=full) (color-levels=32768) 1830 (CIELAB-L-depth=128) 1831 (CIELAB-a-depth=32) 1832 (CIELAB-b-depth=32) ) 1834 - Related standards or documents: 1836 The memo "Media Features for Display, Print, and Fax" [3] 1837 defines a feature (color) for indicating basic color 1838 capabilities. 1840 CIELAB color space is defined in [19] 1842 CIELAB use for fax is described in ITU T.42 [9] 1844 - Related feature tags: 1846 color [3] 1847 color-levels [this document] 1848 color-space [this document] 1850 - Intended usage: 1852 Internet fax 1853 Color image scanning/rendering applications 1855 - Author/Change controller: 1857 IETF 1859 Internet Draft Content Feature Schema for Internet Fax (V2) 1860 5 January 1862 A.7 CIELAB color gamut 1864 - Media Feature tag name(s): 1866 CIELAB-L-min 1867 CIELAB-L-max 1868 CIELAB-a-min 1869 CIELAB-a-max 1870 CIELAB-b-min 1871 CIELAB-b-max 1873 - ASN.1 identifiers associated with these feature tags: 1875 CIELAB-L-min: 1.3.6.1.8.1.15 1876 CIELAB-L-max: 1.3.6.1.8.1.16 1877 CIELAB-a-min: 1.3.6.1.8.1.17 1878 CIELAB-a-max: 1.3.6.1.8.1.18 1879 CIELAB-b-min: 1.3.6.1.8.1.19 1880 CIELAB-b-max: 1.3.6.1.8.1.20 1882 Internet Draft Content Feature Schema for Internet Fax (V2) 1883 5 January 1885 - Summary of the media features indicated: 1887 These feature indicate a supported range of color values, by 1888 indicating minimum and maximum values used for each color 1889 component in a CIELAB color space. 1891 'CIELAB-L-min' and 'CIELAB-L-max' are the minimum and maximum 1892 values of the L* component. 1894 'CIELAB-a-min' and 'CIELAB-a-max' are the minimum and maximum 1895 values of the a* component. 1897 'CIELAB-b-min' and 'CIELAB-b-max' are the minimum and maximum 1898 values of the b* component. 1900 NOTE: color component values are assumed to be rational 1901 numbers, so a limited gamut does not necessarily indicate 1902 limited color resolution. 1904 - Values appropriate for use with this feature tag: 1906 Rational 1908 - The feature tag is intended primarily for use in the following 1909 applications, protocols, services, or negotiation mechanisms: 1911 Color image printing and display applications where the data 1912 resource used may depend upon detailed color handling 1913 capabilities of the recipient. 1915 Scanning applications where the data transferred may depend 1916 upon the detailed color image generation capabilities of the 1917 originator. 1919 Internet Draft Content Feature Schema for Internet Fax (V2) 1920 5 January 1922 - Examples of typical use: 1924 To describe rendering or scanning capabilities: 1926 (& (CIELAB-L-min>=0) 1927 (CIELAB-L-max<=100) 1928 (CIELAB-a-min>=-75) 1929 (CIELAB-a-max<=+75) 1930 (CIELAB-b-min>=-85) 1931 (CIELAB-b-max<=+85) ) 1933 To describe capabilities required by a document: 1935 (& (CIELAB-L-min=20) 1936 (CIELAB-L-max=80) 1937 (CIELAB-a-min=-35) 1938 (CIELAB-a-max=+55) 1939 (CIELAB-b-min=-45) 1940 (CIELAB-b-max=+65) ) 1942 - Related standards or documents: 1944 CIELAB color space is defined in [19] 1946 CIELAB use for fax is described in ITU T.42 [9] 1948 - Interoperability considerations: 1950 When describing a recipient's capabilities, the minimum and 1951 maximum color component values that can be rendered should be 1952 indicated by inequalities as shown in the examples above. 1954 When describing a document, the actual minimum and maximum 1955 color component values used should be indicated, as shown 1956 above. 1958 - Security considerations: 1960 - Privacy concerns, related to exposure of personal information: 1961 Where feature matching is used to select content applicable 1962 to the physical abilities of a user, unusual values for this 1963 feature tag might give an indication of a user's restricted 1964 abilities. 1966 - Related feature tags: 1968 color [3] 1969 color-space [this document] 1971 Internet Draft Content Feature Schema for Internet Fax (V2) 1972 5 January 1974 - Related media types or data formats: 1976 TIFF-FX [7] 1978 - Intended usage: 1980 Internet fax 1981 Color image scanning/rendering applications 1983 - Author/Change controller: 1985 IETF 1987 Internet Draft Content Feature Schema for Internet Fax (V2) 1988 5 January 1990 A.8 Image file structure 1992 - Media Feature tag name(s): 1994 image-file-structure 1996 - ASN.1 identifier associated with this feature tag: 1998 1.3.6.1.8.1.21 2000 - Summary of the media features indicated: 2002 This feature indicates a file structure used for transfer and 2003 presentation of image data. 2005 It does not indicate image data coding: that is described by 2006 separate feature tags (image-coding, etc.). 2008 - Values appropriate for use with this feature tag: 2010 Token 2012 Image file TIFF 2013 structure TIFF-limited 2014 options: TIFF-minimal 2015 TIFF-MRC 2016 TIFF-MRC-limited 2018 (may be extended by further registrations, 2019 to cover non-TIFF image file structures) 2021 - The feature tag is intended primarily for use in the following 2022 applications, protocols, services, or negotiation mechanisms: 2024 Internet fax, and other print or display applications that 2025 transfer image data. 2027 - Examples of typical use: 2029 See Appendix B of this memo. 2031 - Considerations particular to use in individual applications, 2032 protocols, services, or negotiation mechanisms: 2034 This tag is intended to provide information about an image 2035 file structure. Information about image data coding is 2036 provided by other tags. 2038 The following tag values are defined here: 2040 Internet Draft Content Feature Schema for Internet Fax (V2) 2041 5 January 2043 o 'TIFF' indicates image data enclosed and tagged using TIFF 2044 structures described in Adobe's definition of TIFF [20]. 2046 o 'TIFF-limited' indicates image data structured using TIFF, 2047 but with limitations on the placement of Image File 2048 Descriptors (IFDs) within the file, which are indicated in 2049 section 4.4.6 of RFC 2301 [7]. 2051 o 'TIFF-minimal' indicates a TIFF image format that meets the 2052 IFD placement, byte ordering and bit ordering requirements 2053 of the "minimal black and white mode" described in section 2054 3.5 of RFC 2301 [7], also known as TIFF-S. 2056 o 'TIFF-MRC' uses a TIFF image structure [20] augmented with a 2057 sub-IFD structure, described for the "Mixed Raster Content 2058 mode" in section 8.1.2 of RFC 2301 [7], also known as TIFF-M 2059 (see also tag 'MRC-mode'). 2061 o 'TIFF-MRC-limited' is the same as 'TIFF-MRC', except that 2062 the IFD placement is constrained as for 'TIFF-limited'. 2064 Registration of additional image file structure tags should 2065 focus similarly on image file structure issues, not raw image 2066 data compression and coding. As a guide, an image file 2067 structure may contain image data coded in a variety of ways, 2068 and carries information to describe that coding separately 2069 from MIME content-type labelling, etc. 2071 - Related feature tags: 2073 image-coding [this document] 2074 MRC-mode [this document] 2076 - Related media types or data formats: 2078 TIFF-FX [7] 2079 TIFF V6.0 (Adobe) [20] 2081 - Intended usage: 2083 Internet fax 2084 Image scanning/rendering applications 2086 - Author/Change controller: 2088 IETF 2090 Internet Draft Content Feature Schema for Internet Fax (V2) 2091 5 January 2093 A.9 Image data coding 2095 - Media Feature tag name(s): 2097 image-coding 2099 - ASN.1 identifier associated with this feature tag: 2101 1.3.6.1.8.1.22 2103 - Summary of the media features indicated: 2105 This feature tag indicates a form of image data compression 2106 and coding used. 2108 It identifies a generic image coding technique used, without 2109 regard to any specific profiling of that technique that may be 2110 applied. Values for this feature are generally applicable 2111 across a wide range of image transfer applications. 2113 This information is distinct from the image file structure and 2114 MRC information conveyed by the 'image-file-structure' tags. 2116 - Values appropriate for use with this feature tag: 2118 Token MH 2119 MR 2120 MMR 2121 JBIG 2122 JPEG 2124 (may be extended by further registrations) 2126 - The feature tag is intended primarily for use in the following 2127 applications, protocols, services, or negotiation mechanisms: 2129 Internet fax, and other applications that transfer image data. 2131 - Examples of typical use: 2133 See Appendix B of this memo. 2135 Internet Draft Content Feature Schema for Internet Fax (V2) 2136 5 January 2138 - Related standards or documents: 2140 MH, MR: ITU T.4 [13] 2141 MMR: ITU T.6 [14] 2142 JPEG: ITU T.81 [16] 2143 JBIG: ITU T.82 [17] 2145 - Interoperability considerations: 2147 To establish the correct conditions for interoperability 2148 between systems, capabilities to handle the generic image 2149 coding technique and the specific image coding constraints 2150 must be established. 2152 - Related feature tags: 2154 image-coding-constraint [this document] 2155 JBIG-stripe-size [this document] 2156 image-interleave [this document] 2158 - Related media types or data formats: 2160 TIFF-FX [7] 2162 - Intended usage: 2164 Internet fax 2165 Image scanning/rendering applications 2167 - Author/Change controller: 2169 IETF 2171 Internet Draft Content Feature Schema for Internet Fax (V2) 2172 5 January 2174 A.10 Image coding constraint 2176 - Media Feature tag name(s): 2178 image-coding-constraint 2180 - ASN.1 identifier associated with these feature tags: 2182 1.3.6.1.8.1.23 2184 - Summary of the media features indicated: 2186 This feature tag qualifies the 'image-coding' feature with a 2187 specific profile or usage constraints. 2189 Values for this feature are generally specific to some given 2190 value of 'image-coding' and also to some restricted 2191 application or class of applications. 2193 - Values appropriate for use with this feature tag: 2195 Token JBIG-T85 (bi-level, per ITU T.85) 2196 JBIG-T43 (multi-level, per ITU T.43) 2197 JPEG-T4E (per ITU T.4, Annex E) 2199 (may be extended by further registrations) 2201 - The feature tag is intended primarily for use in the following 2202 applications, protocols, services, or negotiation mechanisms: 2204 Internet fax, and other applications that transfer image data. 2206 The specific values for this feature indicated above are 2207 intended for use with Internet fax. 2209 - Examples of typical use: 2211 See Appendix B of this memo. 2213 - Related standards or documents: 2215 JBIG-T85: ITU T.85 [18] 2216 JBIG-T43: ITU T.43 [10] 2217 JPEG-T4E: ITU T.4 Annex E [13] 2219 Internet Draft Content Feature Schema for Internet Fax (V2) 2220 5 January 2222 - Interoperability considerations: 2224 To establish the correct conditions for interoperability 2225 between systems, capabilities to handle the generic image 2226 coding technique and the specific image coding constraints 2227 must be established. 2229 - Related feature tags: 2231 image-coding [this document] 2232 JBIG-stripe-size [this document] 2233 image-interleave [this document] 2235 - Related media types or data formats: 2237 TIFF-FX [7] 2239 - Intended usage: 2241 Internet fax 2242 Color image scanning/rendering applications 2244 - Author/Change controller: 2246 IETF 2248 Internet Draft Content Feature Schema for Internet Fax (V2) 2249 5 January 2251 A.11 JBIG stripe size 2253 - Media Feature tag name(s): 2255 JBIG-stripe-size 2257 - ASN.1 identifier associated with these feature tags: 2259 1.3.6.1.8.1.24 2261 - Summary of the media features indicated: 2263 This feature is a specific usage constraint that is applied to 2264 JBIG image coding (image-coding=JBIG), and indicates the 2265 allowable size for each stripe of an image, except the last. 2267 A stripe of a JBIG image is a delimited horizontal band of 2268 compressed image data that can be decompressed separately from 2269 the surrounding data. 2271 - Values appropriate for use with this feature tag: 2273 Integer (>0) 2275 - The feature tag is intended primarily for use in the following 2276 applications, protocols, services, or negotiation mechanisms: 2278 Internet fax, and other applications that transfer image data. 2280 - Examples of typical use: 2282 (JBIG-stripe-size=128) 2283 (JBIG-stripe-size>0) 2285 - Related standards or documents: 2287 JBIG: ITU T.82 [17] 2288 JBIG-T85: ITU T.85 [18] 2289 JBIG-T43: ITU T.43 [10] 2291 Internet Draft Content Feature Schema for Internet Fax (V2) 2292 5 January 2294 - Considerations particular to use in individual applications, 2295 protocols, services, or negotiation mechanisms: 2297 In the case of Internet fax, the specific constraints allowed 2298 for a receiver are those given as examples above. 2300 Specifying a stripe size that is not limited (JBIG-stripe- 2301 size>0) means that an entire page of image data is encoded as 2302 a single unit. This may place considerable demands on the 2303 memory of a receiving system, as the entire stripe needs to be 2304 buffered in memory. 2306 - Interoperability considerations: 2308 To establish the correct conditions for interoperability 2309 between systems, capabilities to handle the generic image 2310 coding technique and the specific image coding constraints 2311 must be established. 2313 - Related feature tags: 2315 image-coding [this document] 2316 image-coding-constraint [this document] 2317 image-interleave [this document] 2319 - Related media types or data formats: 2321 TIFF-FX [7] 2323 - Intended usage: 2325 Internet fax 2326 Color image scanning/rendering applications 2328 - Author/Change controller: 2330 IETF 2332 Internet Draft Content Feature Schema for Internet Fax (V2) 2333 5 January 2335 A.12 Image interleave 2337 - Media Feature tag name(s): 2339 image-interleave 2341 - ASN.1 identifier associated with this feature tag: 2343 1.3.6.1.8.1.25 2345 - Summary of the media features indicated: 2347 This feature indicates an image interleave capability. 2349 It may be used with JBIG images (image-coding=JBIG) to 2350 indicate color plane interleaving of either stripes or entire 2351 image planes. 2353 - Values appropriate for use with this feature tag: 2355 Token Stripe 2356 Plane 2358 - The feature tag is intended primarily for use in the following 2359 applications, protocols, services, or negotiation mechanisms: 2361 Internet fax, and other applications that transfer image data. 2363 - Examples of typical use: 2365 (image-interleave=stripe) 2366 (image-interleave=[stripe,plane]) 2368 - Considerations particular to use in individual applications, 2369 protocols, services, or negotiation mechanisms: 2371 Specifying a plane interleave means that an entire page of 2372 image data must be buffered in order to generate render the 2373 image. This may place considerable demands on the memory of a 2374 sending or receiving system. 2376 - Related feature tags: 2378 image-coding [this document] 2379 JBIG-stripe-size [this document] 2381 - Related media types or data formats: 2383 TIFF-FX [7] 2385 Internet Draft Content Feature Schema for Internet Fax (V2) 2386 5 January 2388 - Intended usage: 2390 Internet fax 2391 Color image scanning/rendering applications 2393 - Author/Change controller: 2395 IETF 2397 Internet Draft Content Feature Schema for Internet Fax (V2) 2398 5 January 2400 A.13 Color subsampling 2402 - Media Feature tag name(s): 2404 color-subsampling 2406 - ASN.1 identifier associated with this feature tag: 2408 1.3.6.1.8.1.26 2410 - Summary of the media features indicated: 2412 This feature tag indicates whether color information may be 2413 subsampled with respect to luminance data. 2415 It is used with continuous color images (color=full), color 2416 spaces that use separate luminance and color components 2417 (e.g. color-space=LAB), and image file structures that support 2418 color subsampling. 2420 - Values appropriate for use with this feature tag: 2422 String "1:1:1" 2423 This value indicates a full set of color 2424 component samples for each luminance 2425 component sample. 2427 "4:1:1" 2428 This value indicates a set of color samples 2429 for each luminance sample. 2431 (may be extended by further registrations) 2433 - The feature tag is intended primarily for use in the following 2434 applications, protocols, services, or negotiation mechanisms: 2436 Color image printing and display applications where the data 2437 resource used may depend upon color handling capabilities of 2438 the recipient. 2440 Scanning applications where the data transferred may depend 2441 upon the image generation capabilities of the originator. 2443 - Examples of typical use: 2445 (& (color=full) (color-space=[LAB,CIELAB]) 2446 (color-subsampling=["1:1:1","4:1:1"]) ) 2448 Internet Draft Content Feature Schema for Internet Fax (V2) 2449 5 January 2451 - Related feature tags: 2453 color [3] 2454 color-space [this document] 2455 image-file-structure [this document] 2457 - Related media types or data formats: 2459 TIFF-FX [7] 2461 - Intended usage: 2463 Internet fax 2464 Color image scanning/rendering applications 2466 - Author/Change controller: 2468 IETF 2470 Internet Draft Content Feature Schema for Internet Fax (V2) 2471 5 January 2473 A.14 MRC availability and mode 2475 - Media Feature tag name(s): 2477 MRC-mode 2479 - ASN.1 identifier associated with this feature tag: 2481 1.3.6.1.8.1.27 2483 - Summary of the media features indicated: 2485 This feature is used to indicate the availability of MRC 2486 (mixed raster content) image format capability, and also the 2487 MRC mode available. A zero value indicates MRC is not 2488 available, a non-zero value (in the range 1..7) indicates the 2489 available MRC mode number. 2491 An MRC formatted document is actually a collection of several 2492 images, each of which is described by a separate feature 2493 collection. An MRC-capable receiver is presumed to be capable 2494 of accepting any combination of contained images that conform 2495 to the MRC construction rules, where each such image matches 2496 the separately declared resolution, color capability, color 2497 model, image coding, and any other capabilities. 2499 NOTE: an MRC formatted document may appear within a 2500 TIFF image file structure. 2502 Within an MRC-formatted document, multi-level coders 2503 are used for foreground and background images (i.e. 2504 odd-numbered layers: 1, 3, 5, etc.) and bi-level coders 2505 are used for mask layers (i.e. even numbered layers 2, 2506 4, 6, etc.). 2508 - Values appropriate for use with this feature tag: 2510 Integer (0..7) 2512 - The feature tag is intended primarily for use in the following 2513 applications, protocols, services, or negotiation mechanisms: 2515 Internet fax, and other applications that transfer image data. 2517 - Examples of typical use: 2519 See Appendix B of this document. 2521 Internet Draft Content Feature Schema for Internet Fax (V2) 2522 5 January 2524 - Related standards or documents: 2526 ITU T.44 [15] 2528 - Interoperability considerations: 2530 To establish the correct conditions for interoperability 2531 between systems, capabilities to handle the MRC mode and any 2532 contained image coding techniques must be established. 2534 - Related feature tags: 2536 image-coding [this document] 2537 MRC-max-stripe-size [this document] 2539 - Related media types or data formats: 2541 TIFF-FX [7] 2543 - Intended usage: 2545 Internet fax 2546 Color image scanning/rendering applications 2548 - Author/Change controller: 2550 IETF 2552 Internet Draft Content Feature Schema for Internet Fax (V2) 2553 5 January 2555 A.15 MRC maximum stripe size 2557 - Media Feature tag name(s): 2559 MRC-max-stripe-size 2561 - ASN.1 identifier associated with this feature tag: 2563 1.3.6.1.8.1.28 2565 - Summary of the media features indicated: 2567 This feature may be used with MRC coding (MRC-mode>=1), and 2568 indicates the maximum number of scan lines in each MRC stripe. 2570 The value given indicates an upper bound on the stripe size. 2571 The actual value may vary between stripes, and the actual size 2572 for each stripe is indicated in the image data. 2574 - Values appropriate for use with this feature tag: 2576 Integer (>0) 2578 - The feature tag is intended primarily for use in the following 2579 applications, protocols, services, or negotiation mechanisms: 2581 Internet fax, and other applications that transfer image data. 2583 - Examples of typical use: 2585 (MRC-max-stripe-size<=256) 2586 (MRC-max-stripe-size>=0) 2588 - Considerations particular to use in individual applications, 2589 protocols, services, or negotiation mechanisms: 2591 For Internet fax, the legal constraints for an image receiver 2592 are those given as examples above. 2594 - Related feature tags: 2596 MRC-mode [this document] 2598 - Related media types or data formats: 2600 TIFF-FX [7] 2602 Internet Draft Content Feature Schema for Internet Fax (V2) 2603 5 January 2605 - Intended usage: 2607 Internet fax 2608 Color image scanning/rendering applications 2610 - Author/Change controller: 2612 IETF 2614 Internet Draft Content Feature Schema for Internet Fax (V2) 2615 5 January 2617 Appendix B: TIFF mode descriptions 2619 This appendix contains descriptions of the TIFF modes defined by 2620 RFC 2301 [7], presented as feature set expressions in the form 2621 defined by "A syntax for describing media feature sets" [2] and 2622 using the feature schema introduced by this document. 2624 These may be taken as illustrations of the feature set combinations 2625 that are required for the corresponding TIFF profiles described by 2626 RFC 2301. 2628 TIFF-S has no optional elements, so is presented as a single 2629 feature set. Other profiles are presented as (TIFF-x-base) and 2630 (TIFF-x-full) indicating the minimum and full feature sets 2631 associated with each profile. 2633 (TIFF-S) :- 2634 (& (image-file-structure=TIFF-S) 2635 (color=Binary) 2636 (image-coding=MH) (MRC-mode=0) 2637 (| (& (dpi=200) 2638 (dpi-xyratio=[200/100,200/200]) 2639 (size-x=1728/200) ) 2640 (& (dpi=204) 2641 (dpi-xyratio=[204/98,204/196] 2642 (size-x=1728/204) ) ) 2643 (paper-size=A4) ) 2645 Internet Draft Content Feature Schema for Internet Fax (V2) 2646 5 January 2648 (TIFF-F-base) :- 2649 (& (image-file-structure=TIFF-F) 2650 (color=Binary) 2651 (image-coding=MH) (MRC-mode=0) 2652 (dpi=204) 2653 (dpi-xyratio=[204/98,204/196]) 2654 (size-x=1728/204) 2655 (paper-size=A4) ) 2657 (TIFF-F-full) :- 2658 (& (image-file-structure=TIFF-F) 2659 (color=Binary) 2660 (image-coding=[MH,MR,MMR]) (MRC-mode=0) 2661 (| (& (dpi=200) 2662 (dpi-xyratio=[200/100,200/200]) 2663 (size-x=[1728/200,2048/200,2432/200]) ) 2664 (& (dpi=204) 2665 (dpi-xyratio=[204/98,204/196,204/391]) 2666 (size-x=[1728/204,2048/204,2432/204]) ) 2667 (& (dpi=300) 2668 (dpi-xyratio=300/300) 2669 (size-x=[2592/300,3072/300,3648/300]) ) 2670 (& (dpi=400) 2671 (dpi-xyratio=400/400) 2672 (size-x=[3456/400,4096/400,4864/400]) ) 2673 (& (dpi=408) 2674 (dpi-xyratio=408/391) 2675 (size-x=[3456/408,4096/408,4864/408]) ) ) 2676 (paper-size=[A4, B4, A3, letter, legal]) ) 2678 Internet Draft Content Feature Schema for Internet Fax (V2) 2679 5 January 2681 (TIFF-J-base) :- 2682 (& (image-file-structure=TIFF-J) 2683 (color=Binary) 2684 (MRC-mode=0) 2685 (image-coding=JBIG) 2686 (image-coding-constraint=JBIG-T85) 2687 (JBIG-stripe-size=128) 2688 (dpi=204) 2689 (dpi-xyratio=[204/98,204/196]) 2690 (size-x=1728/204) 2691 (paper-size=A4) ) 2693 (TIFF-J-full) :- 2694 (& (image-file-structure=TIFF-J) 2695 (color=Binary) 2696 (MRC-mode=0) 2697 (image-coding=JBIG) 2698 (image-coding-constraint=JBIG-T85) 2699 (JBIG-stripe-size>0) 2700 (| (& (dpi=200) 2701 (dpi-xyratio=[200/100,200/200]) 2702 (size-x=[1728/200,2048/200,2432/200]) ) 2703 (& (dpi=204) 2704 (dpi-xyratio=[204/98,204/196,204/391]) 2705 (size-x=[1728/204,2048/204,2432/204]) ) 2706 (& (dpi=300) 2707 (dpi-xyratio=300/300) 2708 (size-x=[2592/300,3072/300,3648/300]) ) 2709 (& (dpi=400) 2710 (dpi-xyratio=400/400) 2711 (size-x=[3456/400,4096/400,4864/400]) ) 2712 (& (dpi=408) 2713 (dpi-xyratio=408/391) 2714 (size-x=[3456/408,4096/408,4864/408]) ) ) 2715 (paper-size=[A4, B4, A3, letter, legal]) ) 2717 Internet Draft Content Feature Schema for Internet Fax (V2) 2718 5 January 2720 (TIFF-C-base) :- 2721 (& (image-file-structure=TIFF-C) 2722 (color=grey) 2723 (color-levels<=256) 2724 (MRC-mode=0) 2725 (image-coding=JPEG) (image-coding-constraint=JPEG-T4E) 2726 (color-space=CIELAB) 2727 (CIELAB-L-depth<=101) 2728 (CIELAB-L-min>=0) 2729 (CIELAB-L-max<=100) 2730 (color-illuminant=D50) 2731 (dpi=200) (dpi-xyratio=1) 2732 (size-x=864/100) 2733 (paper-size=A4) ) 2735 (TIFF-C-full) :- 2736 (& (image-file-structure=TIFF-C) 2737 (image-coding=JPEG) (image-coding-constraint=JPEG-T4E) 2738 (color-space=CIELAB) 2739 (| (& (color=grey) 2740 (color-levels<=4096) 2741 (CIELAB-L-depth<=4096) ) 2742 (& (color=full) 2743 (color-levels<=68719476736) 2744 (color-subsampling=["4:1:1","1:1:1"]) 2745 (CIELAB-L-depth<=4096) 2746 (CIELAB-a-depth<=4096) 2747 (CIELAB-b-depth<=4096) ) ) 2748 (MRC-mode=0) 2749 (dpi=[100,200,300,400]) (dpi-xyratio=1) 2750 (size-x=[864/100,1024/100,1216/100]) 2751 (paper-size=[A4, B4, A3, letter, legal]) ) 2753 (TIFF-L-base) :- 2754 (& (image-file-structure=TIFF-L) 2755 (MRC-mode=0) 2756 (image-coding=JBIG) 2757 (image-coding-constraint=JBIG-T43) 2758 (JBIG-stripe-size=128) 2759 (image-interleave=stripe) 2760 (color=grey) 2761 (color-levels<=256) 2762 (color-space=CIELAB) 2763 (CIELAB-L-depth=101) 2764 (CIELAB-L-min>=0) 2765 (CIELAB-L-max<=100) 2766 (color-illuminant=D50) 2767 (dpi=200) (dpi-xyratio=1) 2768 (size-x=864/100) 2769 (paper-size=A4) ) 2771 Internet Draft Content Feature Schema for Internet Fax (V2) 2772 5 January 2774 (TIFF-L-full) :- 2775 (& (image-file-structure=TIFF-L) 2776 (MRC-mode=0) 2777 (image-coding=JBIG) 2778 (image-coding-constraint=JBIG-T43) 2779 (JBIG-stripe-size>0) 2780 (image-interleave=[stripe, plane]) 2781 (| (& (color=limited) 2782 (color-levels<=8) 2783 (color-space=[Device-RGB, Device-CMY] ) ) 2784 (& (color=limited) 2785 (color-levels<=16) 2786 (color-space=Device-CMYK) ) 2787 (& (color=mapped) 2788 (color-levels<=65536) 2789 (color-space=CIELAB) 2790 (CIELAB-L-depth<=4096) 2791 (CIELAB-a-depth<=4096) 2792 (CIELAB-b-depth<=4096) ) 2793 (& (color=grey) 2794 (color-levels<=4096) 2795 (color-space=CIELAB) 2796 (CIELAB-L-depth<=4096) ) 2797 (& (color=full) 2798 (color-space=CIELAB) 2799 (color-levels<=68719476736) 2800 (CIELAB-L-depth<=4096) 2801 (CIELAB-a-depth<=4096) 2802 (CIELAB-b-depth<=4096) 2803 (CIELAB-L-min>=0) ) ) 2804 (dpi=[100,200,300,400]) (dpi-xyratio=1) 2805 (size-x=[864/100,1024/100,1216/100]) 2806 (paper-size=[A4, B4, A3, letter, legal]) ) 2808 (TIFF-M-base) :- 2809 (& (image-file-structure=TIFF-M) 2810 (MRC-mode>=1) 2811 (MRC-max-stripe-size<=256) ) 2813 (TIFF-M-full) :- 2814 (& (image-file-structure=TIFF-M) 2815 (MRC-mode>=1) ) 2817 Support for multiple TIFF profiles may be indicated by combining 2818 their expressions with the OR operator; e.g. 2820 (| (TIFF-F) (TIFF-S) (TIFF-J) ) 2822 indicates support for all black-and-white modes. 2824 Internet Draft Content Feature Schema for Internet Fax (V2) 2825 5 January 2827 TIFF-M is a composite mode and must be used in conjunction with 2828 some other mode to define the particular capabilities of a 2829 receiver; e.g. 2831 (| (TIFF-M-base) 2832 (TIFF-S) (TIFF-J-full) (TIFF-C-base) (TIFF-L-full) ) 2834 Each sub-image in an MRC image must conform to the capabilities 2835 indicated AND also to any additional constraints imposed by the MRC 2836 structure, such as bi-level mask layer, etc. See sections A.13 and 2837 section 3.7. 2839 Internet Draft Content Feature Schema for Internet Fax (V2) 2840 5 January 2842 Appendix C: Changes from RFC 2531 2844 00a 23-Jun-1999 Updated Appendix B with more complete TIFF-FX 2845 profile descriptions. Added note to section 3.5 2846 clarifying the meaning of (color=limited) in the 2847 context of Internet fax. Added note to section 2848 3.6 and A.6 to clarify interpretation of color 2849 depth. In A.6, noted that color gamut is not the 2850 same as color resolution; fixed example. Split 2851 section 3.7 into two sections, dealing with simple 2852 image coding options and MRC composite image 2853 options. Added new feature tag 'color-illuminant' 2854 (sections 3.6, A.5). Added cross-references from 2855 TIFF-M image file structure to MRC-mode tag. 2856 Updated introduction and references. 2858 00b 10-Aug-1999 Bring examples into line with T.30 mapping 2859 document [4], and reorganize to make the 2860 expression structure less complex. Add details of 2861 mailing list for discussion. Added JPEG-only 2862 colour example. Change definition of image-file- 2863 structure tag to indicate more precisely what is 2864 being defined, and to draw out the distinction 2865 between a file structure to contain MRC images 2866 (image-file-structure), and the MRC image model 2867 (MRC-mode). 2869 01a 01-Oct-1999 Update author's address and some references. 2871 01b 05-Jan-2000 Incorporate last-call review comments (all 2872 editorial). 2874 Internet Draft Content Feature Schema for Internet Fax (V2) 2875 5 January 2877 Full copyright statement 2879 Copyright (C) The Internet Society 1999. All Rights Reserved. 2881 This document and translations of it may be copied and furnished to 2882 others, and derivative works that comment on or otherwise explain 2883 it or assist in its implementation may be prepared, copied, 2884 published and distributed, in whole or in part, without restriction 2885 of any kind, provided that the above copyright notice and this 2886 paragraph are included on all such copies and derivative works. 2887 However, this document itself may not be modified in any way, such 2888 as by removing the copyright notice or references to the Internet 2889 Society or other Internet organizations, except as needed for the 2890 purpose of developing Internet standards in which case the 2891 procedures for copyrights defined in the Internet Standards process 2892 must be followed, or as required to translate it into languages 2893 other than English. 2895 The limited permissions granted above are perpetual and will not be 2896 revoked by the Internet Society or its successors or assigns. 2898 This document and the information contained herein is provided on 2899 an "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET 2900 ENGINEERING TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR 2901 IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF 2902 THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED 2903 WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.