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diff --git a/doc/rfc/rfc2879.txt b/doc/rfc/rfc2879.txt new file mode 100644 index 0000000..75458fb --- /dev/null +++ b/doc/rfc/rfc2879.txt @@ -0,0 +1,3251 @@ + + + + + + +Network Working Group G. Klyne +Request for Comments: 2879 Content Technologies +Obsoletes: 2531 L. McIntyre +Category: Standards Track Xerox Corporation + August 2000 + + Content Feature Schema for Internet Fax (V2) + +Status of this Memo + + This document specifies an Internet standards track protocol for the + Internet community, and requests discussion and suggestions for + improvements. Please refer to the current edition of the "Internet + Official Protocol Standards" (STD 1) for the standardization state + and status of this protocol. Distribution of this memo is unlimited. + +Copyright Notice + + Copyright (C) The Internet Society (2000). All Rights Reserved. + +Abstract + + This document defines a content media feature schema for Internet + fax. + + It is a profile of the media feature registration mechanisms [1,2,3] + for use in performing capability identification between extended + Internet fax systems [5]. It replaces and updates the feature schema + defined in RFC 2531. + +Table of Contents + + 1. Introduction .............................................2 + 1.1 Organization of this document ........................3 + 1.2 Terminology and document conventions .................3 + 1.3 Discussion of this document ..........................4 + 2. Fax feature schema syntax ................................4 + 3. Internet fax feature tags ................................4 + 3.1 Image size ...........................................5 + 3.2 Resolution ...........................................5 + 3.3 Media type ...........................................6 + 3.4 Paper Size ...........................................6 + 3.5 Color capability .....................................7 + 3.6 Color model ..........................................8 + 3.7 Image coding ........................................11 + 3.8 MRC mode ............................................12 + 4. Examples ................................................13 + 4.1 Simple mode Internet fax system ....................13 + + + +Klyne & McIntyre Standards Track [Page 1] + +RFC 2879 Content Feature Schema for Internet Fax (V2) August 2000 + + + 4.2 High-end black-and-white Internet fax system.........14 + 4.3 Grey-scale Internet fax system ......................14 + 4.4 Full-color Internet fax system (JPEG only) ..........15 + 4.5 Full-color Internet fax system (JPEG and JBIG) ......16 + 4.6 Full-color Internet fax system (MRC) ................17 + 4.7 Sender and receiver feature matching ................19 + 5. IANA Considerations .....................................21 + 6. Security Considerations .................................21 + 6.1 Capability descriptions and mechanisms ..............21 + 6.2 Specific threats ....................................21 + 7. Acknowledgements ........................................22 + 8. References ..............................................22 + 9. Authors' Addresses ......................................24 + Appendix A: Feature registrations ..........................25 + A.1 Image size ..........................................25 + A.2 Resolution aspect ratio .............................27 + A.3 Color levels ........................................28 + A.4 Color space ........................................30 + A.5 CIELAB color illuminant .............................33 + A.6 CIELAB color depth ..................................35 + A.7 CIELAB color gamut ..................................37 + A.8 Image file structure ................................39 + A.9 Image data coding ...................................41 + A.10 Image coding constraint ............................43 + A.11 JBIG stripe size .................................. 44 + A.12 Image interleave ...................................46 + A.13 Color subsampling ..................................47 + A.14 MRC availability and mode ..........................49 + A.15 MRC maximum stripe size ............................50 + Appendix B: TIFF mode descriptions .........................52 + Appendix C: Changes from RFC 2531 ..........................57 + Full Copyright Statement ...................................58 + +1. Introduction + + This document defines a content media feature schema for Internet + fax. + + It is a profile of the media feature registration mechanisms [1,2,3] + for use in performing capability identification between extended + Internet fax systems [5]. It replaces and updates the feature schema + defined in RFC 2531. + + The media feature description mechanisms do not describe any specific + mechanisms for communicating capability information, but do presume + that any such mechanisms will transfer textual values. In + conjunction with this feature schema, they specify a textual format + to be used for describing Internet Fax capability information. + + + +Klyne & McIntyre Standards Track [Page 2] + +RFC 2879 Content Feature Schema for Internet Fax (V2) August 2000 + + + The range of capabilities that can be indicated are based on those + covered by the TIFF file format for Internet fax [7] and Group 3 + facsimile [6]. A companion document [4] describes the relationship + and mapping between this schema and Group 3 fax capabilities. + +1.1 Organization of this document + + Section 2 specifies the overall syntax for fax feature descriptions + by reference to the media feature registration and syntax documents + [1,2]. + + Section 3 enumerates the feature tags that are to be recognized and + processed by extended Internet fax systems, according to their + capabilities. + + Appendix A contains additional feature tag registrations for media + features that are specific to fax and for which no applicable + registration already exists. These are presented in the form + prescribed by the media feature registration procedure [1]. + +1.2 Terminology and document conventions + + The term "extended Internet fax system" is used to describe any + software, device or combination of these that conforms to the + specification "Extended Facsimile Using Internet Mail" [5]. + + "capability exchange" describes any transfer of information between + communicating systems that is used to indicate system capabilities + and hence determine the form of data transferred. This term covers + both one-way and two-way transfers of capability information. + + "capability identification" is a particular form of capability + exchange in which a receiving system provides capability information + to a sending system. + + "capability description" is a collection of data presented in some + specific format that describes the capabilities of some communicating + entity. It may exist separately from any specific capability + exchange mechanism. + + NOTE: Comments like this provide additional nonessential + information about the rationale behind this document. + Such information is not needed for building a conformant + implementation, but may help those who wish to understand + the design in greater depth. + + + + + + +Klyne & McIntyre Standards Track [Page 3] + +RFC 2879 Content Feature Schema for Internet Fax (V2) August 2000 + + +1.3 Discussion of this document + + Discussion of this document should take place on the Internet fax + mailing list hosted by the Internet Mail Consortium (IMC). Please + send comments regarding this document to: + + ietf-fax@imc.org + + To subscribe to this list, send a message with the body 'subscribe' + to "ietf-fax-request@imc.org". + + To see what has gone on before you subscribed, please see the mailing + list archive at: + + http://www.imc.org/ietf-fax/ + +2. Fax feature schema syntax + + The syntax for the fax feature schema is described by "A syntax for + describing media feature sets" [2]. This in turn calls upon media + feature tags that may be registered according to the procedure + described in "Media Feature Tag Registration Procedure" [1]. + + NOTE: Media feature registration provides a base + vocabulary of features that correspond to media handling + capabilities. The feature set syntax provides a + mechanism and format for combining these to describe + combinations of features. This memo indicates those + features that may be associated with extended Internet + fax systems. + +3. Internet fax feature tags + + This section enumerates and briefly describes a number of feature + tags that are defined for use with extended Internet fax systems and + applications. These tags may be used also by other systems and + applications that support corresponding capabilities. + + The feature tags presented below are those that an extended Internet + fax system is expected to recognize its ability or non-ability to + handle. + + Definitive descriptions of feature tags are indicated by reference to + their registration according to the media feature registration + procedure [1] (some of which are appended to this document). + + + + + + +Klyne & McIntyre Standards Track [Page 4] + +RFC 2879 Content Feature Schema for Internet Fax (V2) August 2000 + + + NOTE: The presence of a feature tag in this list does + not mean that an extended Internet fax system must have + that capability; rather, it must recognize the feature + tag and deal with it according to the capabilities that + it does have. + + Further, an extended Internet fax system is not prevented + from recognizing and offering additional feature tags. + The list below is intended to provide a basic vocabulary + that all extended Internet fax systems can use in a + consistent fashion. + + If an unrecognized or unused feature tag is received, the + feature set matching rule (described in [2]) operates so + that tag is effectively ignored. + +3.1 Image size + + Feature tag name Legal values + ---------------- ------------ + size-x <Rational> (>0) + size-y <Rational> (>0) + + Reference: this document, Appendix A. + + These feature values indicate a rendered document size in inches. + + Where the actual size is measured in millimetres, a conversion + factor of 10/254 may be applied to yield an exact inch-based value. + +3.2 Resolution + + Feature tag name Legal values + ---------------- ------------ + dpi <Integer> (>0) + dpi-xyratio <Rational> (>0) + + Reference: "Media Features for Display, Print, and Fax" [3], and this + document appendix A. + + If 'dpi-xyratio' is present and not equal to 1 then the horizontal + resolution (x-axis) is indicated by the 'dpi' feature value, and the + vertical resolution (y-axis) is the value of 'dpi' divided by 'dpi- + xyratio'. + + + + + + + +Klyne & McIntyre Standards Track [Page 5] + +RFC 2879 Content Feature Schema for Internet Fax (V2) August 2000 + + + For example, the basic Group 3 fax resolution of 200*100dpi might be + indicated as: + + (& (dpi=200) (dpi-xyratio=200/100) ) + + When describing resolutions for an MRC format document, the complete + set of usable resolutions is listed. However, there are some + restrictions on their use: (a) 100dpi resolution can be used only + with multi-level images, and (b) any multi-level image resolution is + required to be an integral sub-multiple of the applicable mask + resolution. + +3.3 Media type + + Feature tag name Legal values + ---------------- ------------ + ua-media screen + screen-paged + stationery + transparency + envelope + envelope-plain + continuous + + Reference: "Media Features for Display, Print, and Fax" [3]. + + NOTE: Where the recipient indicates specific support for + hard copy or soft copy media type, a sender of color + image data may wish to adjust the color components (e.g. + per the related rules of ITU recommendation T.42 [9]) to + improve rendered image quality on that medium. + +3.4 Paper Size + + Feature tag name Legal values + ---------------- ------------ + paper-size A4 + A3 + B4 + letter + legal + + Reference: "Media Features for Display, Print, and Fax" [3]. + + + + + + + + +Klyne & McIntyre Standards Track [Page 6] + +RFC 2879 Content Feature Schema for Internet Fax (V2) August 2000 + + +3.5 Color capability + + Feature tag name Legal values + ---------------- ------------ + color Binary (bi-level only) + Limited (a limited number of colors) + Mapped (palette or otherwise mapped color) + Grey (grey-scale only) + Full (full continuous-tone color) + + Reference: "Media Features for Display, Print, and Fax" [3]. + + The intention here is to give a broad indication of color handling + capabilities that might be used, for example, to select among a small + number of available data resources. + + The value of this feature also gives an indication of the more + detailed color handling features that might be applicable (see next + section). + + 'Binary' indicates blank-and-white, or other bi-level capability. No + further qualifying feature tags are required. + + 'Limited' indicates a small number of distinct fixed colors, such as + might be provided by a highlight printer, pen plotter or limited + color display. The 'color-levels' tag should be used to indicate the + number of distinct colors available. + + NOTE: No ability to indicate any specific or named color + is implied by this option. Some devices might use + different intensity levels rather than different hues for + distinction. + + In the context of Internet fax, 'limited' is interpreted as one-bit- + per-color-sample (RGB, CMY or CMYK), depending on the color space + used. + + 'Mapped' indicates that pixel color values are mapped in some + specifiable way to a multi-component color space. The 'color-levels' + tag may be used to indicate the number of distinct colors available; + in its absence, sufficient levels to display a photographic image + should be assumed. + + 'Grey' indicates a continuous tone grey-scale capability. + + 'Full' indicates full continuous tone color capability. + + + + + +Klyne & McIntyre Standards Track [Page 7] + +RFC 2879 Content Feature Schema for Internet Fax (V2) August 2000 + + + For 'Mapped', 'Grey' and 'Full' color, additional feature tags + (section 3.6) may be used to further qualify the color reproduction. + +3.6 Color model + + Feature tag name Legal values + ---------------- ------------ + color-levels <integer> (>2) + color-space Device-RGB (device RGB) + Device-CMY (device CMY) + Device-CMYK (device CMYK) + CIELAB (LAB per T.42 [9]) + (may be extended by further registrations) + color-illuminant <token> (per ITU T.4 [13], E.6.7) + D50 + D65 + D75 + SA + SC + F2 + F7 + F11 + CTnnnn (see below) + CIELAB-L-depth <integer> (>0) + CIELAB-a-depth " + CIELAB-b-depth " + CIELAB-L-min <integer> + CIELAB-L-max " + CIELAB-a-min " + CIELAB-a-max " + CIELAB-b-min " + CIELAB-b-max " + + Reference: this document, appendix A. + + The general model for image handling (both color and non-color) is + described here from a receiver's perspective; a similar model + operates in the reverse direction for a scan/send perspective: + + raw bit pixel color physical + stream -(A)-> values -(B)-> values -(C)-> rendition + + - "raw bit stream" is a stream of coded bits + + (A) indicates image coding/decoding (MH,MR,MMR,JPEG,JBIG,etc.) + + - "pixel values" are a single numeric value per picture element + that designates the color of that element. + + + +Klyne & McIntyre Standards Track [Page 8] + +RFC 2879 Content Feature Schema for Internet Fax (V2) August 2000 + + + (B) indicates pixel-to-color value mapping + + - "color values" have a separate numeric value for each color + component (i.e. L*, a*, b* in the case of CIELAB indicated + above.) + + (C) indicates how the color values are related to a physical + color. This involves interpretation of the color value with + respect to a color model (e.g. RGB, L*a*b*, CMY, CMYK) and a + color space (which is typically recipient-dependent). + + - "physical rendition" is a color value physically realized on a + display, printer or other device. + + There are many variables that can be applied at each stage of the + processing of a color image, and any may be critical to meaningful + handling of that image in some circumstances. In other circumstances + many of the variables may be implied (to some level of approximation) + in the application that uses them (e.g. color images published on a + Web page). + + The color feature framework described here is intended to allow + capability description at a range of granularity: feature tags which + correspond to implied (or "don't care" or "unknown") feature values + may simply be omitted from a capability description. + + Grey scale and bi-level images are handled within this framework as a + special case, having a 1-component color model. The following + features are used for describing color capabilities: + + 'color-levels' indicates the number of distinct values for each + picture element, and applies to all but bi-level images. For bi- + level images, a value of 2 is implied. + + 'color-space' is used mainly with 'Mapped' and 'Full', but could be + used with other modes if the exact color or color model used is + significant. Two kinds of color space can be distinguished: + device-dependent and calibrated. Device dependent spaces are named + here as 'Device-xxx', and are used to indicate a color space that is + defined by the receiving device. Calibrated color spaces presume the + existence of a rendering system that is calibrated with respect to an + indicated definition, and is capable of processing the device- + independent color information accordingly. + + + + + + + + +Klyne & McIntyre Standards Track [Page 9] + +RFC 2879 Content Feature Schema for Internet Fax (V2) August 2000 + + + A color-handling receiver should indicate any appropriate device + color space capability in addition to any calibrated color spaces + that it may support. A calibrated color space should be used when + precise color matching is required in the absence of specific + knowledge of the receiving system. + + NOTE: In practice, although they appear to be separate + concepts, the color model and color space cannot be + separated. In the final analysis, a color model (RGB, + CMY, etc.) must be defined with respect to some color + space. + + 'color-illuminant' indicates a CIE illuminant, using the same general + form that is used for this purpose by Group 3 fax (as defined in ITU + T.4 [13], section E.6.7). When the illuminant is specified by its + color temperature, the token string 'CTnnnn' is used, where 'nnnn' is + a decimal number that is the color temperature in Kelvins; e.g. + CT7500 indicates an illuminant color temperature of 7500K. + + NOTE: ITU T.4 indicates a binary representation for color + temperature values. + + In practice, much of the illuminant detail given here + will probably be unused by Internet fax. The only value + likely to be specified is 'D50', which is the default + color illuminant for Group 3 fax. + + 'CIELAB-L-depth', 'CIELAB-a-depth' and 'CIELAB-b-depth' indicate the + number of different values that are possible for the L*, a* and b* + color components respectively, and are significant only when colors + are represented in a CIELAB color space. These features would be + used with palletized color, or with full color where each color + component has a different number of possible values. + + Color depth values relate to the representation of colour values + rather than the resolution of a scanning or rendering device. Thus, + if 256 different L-component values can be represented then the + assertion (CIELAB-L-depth<=256) is used, even if a receiving device + can render only 100 distinct luminance values. (Color rendering + resolution is not covered by this memo.) + + The 'CIELAB-x-min' and 'CIELAB-x-max' values indicate a color gamut + (i.e. a range of color values that are used or may be rendered). A + gamut may be indicated in terms of the CIELAB color space even when + colors are represented in some other space. + + + + + + +Klyne & McIntyre Standards Track [Page 10] + +RFC 2879 Content Feature Schema for Internet Fax (V2) August 2000 + + +3.7 Image coding + + Feature tag name Legal values + ---------------- ------------ + image-file- TIFF + structure TIFF-limited + TIFF-minimal + TIFF-MRC + TIFF-MRC-limited + (may be extended by further registrations) + image-coding MH + MR + MMR + JBIG + JPEG + (may be extended by further registrations) + image-coding- JBIG-T85 (bi-level, per ITU T.85) + constraint JBIG-T43 (multi-level, per ITU T.43) + JPEG-T4E (per ITU T.4, Annex E) + (may be extended by further registrations) + JBIG-stripe-size <Integer> + image-interleave Stripe + Plane + color-subsampling "1:1:1" (no color subsampling) + "4:1:1" (4:1:1 color subsampling) + + Reference: this document, appendix A. + + 'image-file-structure' defines how the coded image data is wrapped + and formatted. The following options are defined here: + + o 'TIFF' indicates image data enclosed and tagged using TIFF + structures described in Adobe's definition of TIFF [20]. + + o 'TIFF-limited' indicates image data structured using TIFF, but + with the limitations on the placement of Image File Descriptors + (IFDs) indicated in section 4.4.6 of RFC 2301 [7]. + + o 'TIFF-minimal' indicates a TIFF image format that meets the IFD + placement, byte ordering and bit ordering requirements of the + "minimal black and white mode" described in section 3.5 of RFC + 2301 [7], also known as TIFF-S. + + o 'TIFF-MRC' uses a TIFF image structure [20] augmented with a sub- + IFD structure, described for the "Mixed Raster Content mode" in + section 8.1.2 of RFC 2301 [7], also known as TIFF-M. This + provides a file structure to contain composite images constructed + using the MRC model described in T.44 [15] (see tag 'MRC-mode'). + + + +Klyne & McIntyre Standards Track [Page 11] + +RFC 2879 Content Feature Schema for Internet Fax (V2) August 2000 + + + o 'TIFF-MRC-limited' is the same as 'TIFF-MRC', except that the + primary IFD (i.e. top-level IFDs, as opposed to sub-IFDs) + placement is constrained in the same way as 'TIFF-limited'. + + 'image-coding' describes how raw image data is compressed and coded + as a sequence of bits. These are generic tags that may apply to a + range of file formats and usage environments. + + 'image-coding-constraint' describes how the raw image data coding + method is constrained to meet a particular operating environment. + Options defined here are JBIG and JPEG coding constraints that apply + in typical Group 3 fax environments. + + The 'JBIG-stripe-size' feature may be used with JBIG image coding, + and indicates the number of scan lines in each stripe except the last + in an image. The legal constraints are: + + (JBIG-stripe-size=128) + (JBIG-stripe-size>=0) + + The latter being equivalent to no restriction. + + NOTE: there are several image coding options here, and + not all are required in all circumstances. + + Specification of the image-file-structure tag value alone + is not normally sufficient to describe the capabilities + of a recipient. A general rule is that sufficient detail + should be provided to exclude any unsupported features. + + For extended Internet fax, image-file-structure and + image-coding should always be specified, together with + additional values described above as needed to clearly + indicate which feature tag values are supported and which + are not. (See also the examples in section 4.) + +3.8 MRC mode + + Feature tag name Legal values + ---------------- ------------ + MRC-mode <Integer> (0..7) (per ITU T.44 [15]) + MRC-max-stripe-size <Integer> + + Reference: this document, appendix A. + + + + + + + +Klyne & McIntyre Standards Track [Page 12] + +RFC 2879 Content Feature Schema for Internet Fax (V2) August 2000 + + + The 'MRC-mode' feature is used to indicate the availability of MRC + (mixed raster content) image format capability. A zero value + indicates MRC is not available, a non-zero value indicates the + maximum available MRC mode number. + + An MRC formatted document is actually a collection of several images, + each of which is described by a separate feature collection. An + MRC-capable receiver is presumed to be capable of accepting any + combination of contained images that conform to both the MRC + construction rules and the image-coding capabilities declared + elsewhere. + + Within an MRC-formatted document, multi-level coders are used for + foreground and background images (i.e. odd-numbered layers: 1, 3, 5, + etc.) and bi-level coders are used for mask layers (i.e. even + numbered layers 2, 4, 6, etc.). MRC format also imposes constraints + on the resolutions that can be used. + + The 'MRC-max-stripe-size' feature may be used with MRC coding, and + indicates the maximum number of scan lines in each MRC stripe. The + legal constraints are: + + (MRC-max-stripe-size<=256) + (MRC-max-stripe-size>=0) + + These values indicate upper bounds on the stripe size. The actual + value may vary between stripes, and the actual size for each stripe + is indicated in the image data. + +4. Examples + + The level of detail captured here reflects that used for capability + identification in Group 3 facsimile. + +4.1 Simple mode Internet fax system + + This example describes the capabilities of a typical simple mode + Internet fax system. Note that TIFF profile S is required to be + supported by such a system. + + (& (image-file-structure=TIFF-minimal) + (MRC-mode=0) + (color=Binary) + (image-coding=MH) (MRC-mode=0) + (| (& (dpi=204) (dpi-xyratio=[204/98,204/196]) ) + (& (dpi=200) (dpi-xyratio=[200/100,1]) ) ) + (size-x<=2150/254) + (paper-size=A4) + + + +Klyne & McIntyre Standards Track [Page 13] + +RFC 2879 Content Feature Schema for Internet Fax (V2) August 2000 + + + (ua-media=stationery) ) + +4.2 High-end black-and-white Internet fax system + + This would include support for B/W JBIG and be equivalent to what is + sometimes called "Super G3", except that Internet fax functionality + would be added. + + (& (image-file-structure=TIFF) + (MRC-mode=0) + (color=Binary) + (| (& (dpi=204) (dpi-xyratio=[204/98,204/196]) ) + (& (dpi=200) (dpi-xyratio=[200/100,1]) ) + (& (dpi=300) (dpi-xyratio=1) ) ) + (| (image-coding=[MH,MR,MMR]) + (& (image-coding=JBIG) + (image-coding-constraint=JBIG-T85) + (JBIG-stripe-size=128) ) ) + (size-x<=2150/254) + (paper-size=[letter,A4,B4]) ) + (ua-media=stationery) ) + +4.3 Grey-scale Internet fax system + + This is the previous example extended to handle grey scale multi- + level images. In keeping with Group 3 fax, this example requires + equal x- and y- resolutions for a multi-level image. + + (& (image-file-structure=TIFF) + (MRC-mode=0) + (| (& (color=Binary) + (| (image-coding=[MH,MR,MMR]) + (& (image-coding=JBIG) + (image-coding-constraint=JBIG-T85) + (JBIG-stripe-size=128) ) ) + (| (& (dpi=204) (dpi-xyratio=[204/98,204/196]) ) + (& (dpi=200) (dpi-xyratio=[200/100,1]) ) + (& (dpi=300) (dpi-xyratio=1) ) ) + (& (color=Grey) + (color-levels<=256) + (color-space-CIELAB) + (color-illuminant=D50) + (CIELAB-L-min>=0) + (CIELAB-L-max<=100) + (| (& (image-coding=JPEG) + (image-coding-constraint=JPEG-T4E) ) + (& (image-coding=JBIG) + (image-coding-constraint=JBIG-T43) + + + +Klyne & McIntyre Standards Track [Page 14] + +RFC 2879 Content Feature Schema for Internet Fax (V2) August 2000 + + + (JBIG-stripe-size=128) + (image-interleave=stripe) ) ) + (dpi=[100,200,300]) (dpi-xyratio=1) ) ) + (size-x<=2150/254) + (paper-size=[letter,A4,B4]) ) + (ua-media=stationery) ) + +4.4 Full-color Internet fax system (JPEG only) + + This adds 24-bit full-color to the previous example. + + (& (image-file-structure=TIFF) + (MRC-mode=0) + (| (& (color=Binary) + (image-coding=[MH,MR,MMR]) + (| (& (dpi=204) (dpi-xyratio=[204/98,204/196]) ) + (& (dpi=200) (dpi-xyratio=[200/100,1]) ) + (& (dpi=300) (dpi-xyratio=1) ) ) ) + (& (color=grey) + (image-coding=JPEG) + (image-coding-constraint=JPEG-T4E) + (color-levels<=256) + (color-space=CIELAB) + (color-illuminant=D50) + (CIELAB-L-min>=0) + (CIELAB-L-max<=100) + (dpi=[100,200,300]) (dpi-xyratio=1) ) + (& (color=full) + (image-coding=JPEG) + (image-coding-constraint=JPEG-T4E) + (color-subsampling=["1:1:1","4:1:1"]) + (color-levels<=16777216) + (color-space=CIELAB) + (color-illuminant=D50) + (CIELAB-L-min>=0) + (CIELAB-L-max<=100) + (CIELAB-a-min>=-85) + (CIELAB-a-max<=85) + (CIELAB-b-min>=-75) + (CIELAB-b-max<=125) + (dpi=[100,200,300]) (dpi-xyratio=1) ) ) + (size-x<=2150/254) + (paper-size=[letter,A4,B4]) ) + (ua-media=stationery) ) + + + + + + + +Klyne & McIntyre Standards Track [Page 15] + +RFC 2879 Content Feature Schema for Internet Fax (V2) August 2000 + + +4.5 Full-color Internet fax system (JPEG and JBIG) + + This adds limited CMY(K), RGB and 16-bit mapped color using JBIG + coding to the previous example. + + (& (image-file-structure=TIFF) + (MRC-mode=0) + (| (& (color=Binary) + (| (image-coding=[MH,MR,MMR]) + (& (image-coding=JBIG) + (image-coding-constraint=JBIG-T85) + (JBIG-stripe-size=128) ) ) + (| (& (dpi=204) (dpi-xyratio=[204/98,204/196]) ) + (& (dpi=200) (dpi-xyratio=[200/100,1]) ) + (& (dpi=300) (dpi-xyratio=1) ) ) ) + (& (color=Limited) + (image-coding=JBIG) + (image-coding-constraint=JBIG-T43) + (JBIG-stripe-size=128) + (image-interleave=stripe) + (| (& (color-space=[Device-RGB,Device-CMY]) + (color-levels<=8) ) + (& (color-space=Device-CMYK) + (color-levels<=16) ) ) + (dpi=[100,200,300]) (dpi-xyratio=1) ) + (& (color=Mapped) + (image-coding=JBIG) + (image-coding-constraint=JBIG-T43) + (JBIG-stripe-size=128) + (image-interleave=stripe) + (color-levels<=65536) + (color-space=CIELAB) + (color-illuminant=D50) + (CIELAB-L-min>=0) + (CIELAB-L-max<=100) + (CIELAB-a-min>=-85) + (CIELAB-a-max<=85) + (CIELAB-b-min>=-75) + (CIELAB-b-max<=125) + (dpi=[100,200,300]) (dpi-xyratio=1) ) + (& (color=grey) + (| (& (image-coding=JPEG) + (image-coding-constraint=JPEG-T4E) ) + (& (image-coding=JBIG) + (image-coding-constraint=JBIG-T43) + (JBIG-stripe-size=128) + (image-interleave=stripe) ) ) + (color-levels<=256) + + + +Klyne & McIntyre Standards Track [Page 16] + +RFC 2879 Content Feature Schema for Internet Fax (V2) August 2000 + + + (color-space=CIELAB) + (color-illuminant=D50) + (CIELAB-L-min>=0) + (CIELAB-L-max<=100) + (dpi=[100,200,300]) (dpi-xyratio=1) ) + (& (color=full) + (| (& (image-coding=JPEG) + (image-coding-constraint=JPEG-T4E) + (color-subsampling=["1:1:1","4:1:1"]) ) + (& (image-coding=JBIG) + (image-coding-constraint=JBIG-T43) + (JBIG-stripe-size=128) + (image-interleave=stripe) ) ) + (color-levels<=16777216) + (color-space=CIELAB) + (color-illuminant=D50) + (CIELAB-L-min>=0) + (CIELAB-L-max<=100) + (CIELAB-a-min>=-85) + (CIELAB-a-max<=85) + (CIELAB-b-min>=-75) + (CIELAB-b-max<=125) + (dpi=[100,200,300]) (dpi-xyratio=1) ) ) + (size-x<=2150/254) + (paper-size=[letter,A4,B4]) ) + (ua-media=stationery) ) + +4.6 Full-color Internet fax system (MRC) + + This adds MRC image structures to the previous example. + + (& (image-file-structure=TIFF-MRC) + (MRC-mode<=1) (MRC-max-stripe-size>=0) + (| (& (color=binary) + (| (image-coding=[MH,MR,MMR]) + (& (image-coding=JBIG) + (image-coding-constraint=JBIG-T85) + (JBIG-stripe-size=128) ) ) + (| (& (dpi=204) (dpi-xyratio=[204/98,204/196]) ) + (& (dpi=200) (dpi-xyratio=[200/100,1]) ) + (& (dpi=[300,400]) (dpi-xyratio=1) ) ) ) + (& (color=limited) + (| (& (color-space=[Device-RGB,Device-CMY]) + (color-levels<=8) ) ) + (| (& (color-space=Device-CMYK) + (color-levels<=16) ) ) + (image-coding=JBIG) + (image-coding-constraint=JBIG-T43) + + + +Klyne & McIntyre Standards Track [Page 17] + +RFC 2879 Content Feature Schema for Internet Fax (V2) August 2000 + + + (JBIG-stripe-size=128) + (image-interleave=stripe) + (dpi=[100,200,300,400]) (dpi-xyratio=1) ) + (& (color=mapped) + (color-levels<=65536) + (image-coding=JBIG) + (image-coding-constraint=JBIG-T43) + (JBIG-stripe-size=128) + (image-interleave=stripe) + (color-space=CIELAB) + (CIELAB-L-min>=0) + (CIELAB-L-max<=100) + (CIELAB-a-min>=-85) + (CIELAB-a-max<=85) + (CIELAB-b-min>=-75) + (CIELAB-b-max<=125) ) ) + (color-illuminant=D50) + (dpi=[100,200,300,400]) (dpi-xyratio=1) ) + (& (color=grey) + (| (& (image-coding=JPEG) + (image-coding-constraint=JPEG-T4E) ) + (& (image-coding=JBIG) + (image-coding-constraint=JBIG-T43) + (JBIG-stripe-size=128) + (image-interleave=stripe) ) ) + (color-space=CIELAB) + (color-levels<=256) + (color-illuminant=D50) + (CIELAB-L-min>=0) + (CIELAB-L-max<=100) + (dpi=[100,200,300,400]) (dpi-xyratio=1) ) + (& (color=full) + (| (& (image-coding=JPEG) + (image-coding-constraint=JPEG-T4E) + (color-subsampling=["1:1:1","4:1:1"]) ) + (& (image-coding=JBIG) + (image-coding-constraint=JBIG-T43) + (JBIG-stripe-size=128) + (image-interleave=stripe) ) ) + (color-levels<=16777216) + (color-space=CIELAB) + (color-illuminant=D50) + (CIELAB-L-min>=0) + (CIELAB-L-max<=100) + (CIELAB-a-min>=-85) + (CIELAB-a-max<=85) + (CIELAB-b-min>=-75) + (CIELAB-b-max<=125) + + + +Klyne & McIntyre Standards Track [Page 18] + +RFC 2879 Content Feature Schema for Internet Fax (V2) August 2000 + + + (dpi=[100,200,300,400]) (dpi-xyratio=1) ) ) + (size-x<=2550/254) + (Paper-size=[Letter,A4,B4]) + (ua-media=stationery) ) + +4.7 Sender and receiver feature matching + + This example considers sending a document to an enhanced black-and- + white fax system with the following receiver capabilities: + + (& (| (& (dpi=200) (dpi-xyatio=200/100) ) + (& (dpi=200) (dpi-xyratio=1) ) + (& (dpi=300) (dpi-xyratio=1) ) + (& (dpi=400) (dpi-xyratio=1) ) ) + (color=Binary) + (| (& (paper-size=A4) (ua-media=[stationery,transparency]) ) + (& (paper-size=B4) (ua-media=continuous) ) ) + (image-coding=[MH,MR,JBIG]) ) + + Turning to the document itself, assume it is available to the sender + in three possible formats, A4 high resolution, B4 low resolution and + A4 high resolution color, described by: + + (& (dpi=300) (dpi-xyratio=1) + (color=Binary) + (paper-size=A4) + (image-coding=[MMR,JBIG]) ) + + (& (dpi=200) (dpi-xyratio=200/100) + (color=Binary) + (paper-size=B4) + (image-coding=[MH,MR]) ) + + (& (dpi=300) (dpi-xyratio=1) + (color=Mapped) (color-levels<=256) + (paper-size=A4) + (image-coding=JPEG) ) + + These three image formats can be combined into a composite capability + statement by a logical-OR operation (to describe format-1 OR format-2 + OR format-3): + + (| (& (dpi=300) (dpi-xyratio=1) + (color=Binary) + (paper-size=A4) + (image-coding=[MMR,JBIG]) ) + (& (dpi=200) (dpi-xyratio=200/100) + (color=Binary) + + + +Klyne & McIntyre Standards Track [Page 19] + +RFC 2879 Content Feature Schema for Internet Fax (V2) August 2000 + + + (paper-size=B4) + (image-coding=[MH,MR]) ) + (& (dpi=300) (dpi-xyratio=1) + (color=Mapped) (color-levels=42) + (paper-size=A4) + (image-coding=JPEG) ) ) + + This could be simplified, but there is little gain in doing so at + this point. + + The composite document description can be matched with the receiver + capability description, according to the rules in [2], to yield the + result: + + (| (& (dpi=300) (dpi-xyratio=1) + (color=Binary) + (paper-size=A4) + (ua-media=[stationery,transparency]) + (image-coding=JBIG) ) + (& (dpi=200) (dpi-xyratio=200/100) + (color=Binary) + (paper-size=B4) + (ua-media=continuous) + (image-coding=[MH,MR]) ) ) + + Points to note about the feature matching process: + + o The color document option is eliminated because the receiver + cannot handle either color (indicated by '(color=Mapped)') or + JPEG coding (indicated by '(image-coding=JPEG)'). + + o The high resolution version of the document with '(dpi=300)' must + be send using '(image-coding=JBIG)' because this is the only + available coding of the image data that the receiver can use for + high resolution documents. (The available 300dpi document + codings here are MMR and JBIG, and the receiver capabilities are + MH, MR and JBIG.) + + o The low-resolution version of the document can be sent with + either MH or MR coding as the receiver can deal with either of + these for low resolution documents. + + o The high resolution variant of the document is available only for + A4, so that is the paper-size used in that case. Similarly the + low resolution version is sent for B4 paper. + + o Even though the sender may not understand the 'ua-media' feature + tag, and does not mention it, the matching rules preserve the + + + +Klyne & McIntyre Standards Track [Page 20] + +RFC 2879 Content Feature Schema for Internet Fax (V2) August 2000 + + + constraint that the B4 document is rendered with + '(ua-media=continuous)', and the A4 document may be rendered with + '(ua-media=[stationery,transparency])'. + + Finally, note that when matching an MRC document description, the + description of each component sub-image must match the capabilities + of the intended receiver. + +5. IANA Considerations + + Appendix A of this document repeats the descriptions of feature tags + introduced by RFC 2531 [22], with some small revisions. These have + been registered in the "IETF tree", according to the procedure + described in section 3.1.1 of "Media Feature Tag Registration + Procedure" [1] (i.e. these feature tags are subject to the "IETF + Consensus" policies described in RFC 2434 [21]). + + Appendix section A.5 introduces one new feature tag (color- + illuminant) to be registered according to the same procedure. An + ASN.1 identifier should be assigned for this new tag and replaced in + the body of the registration. + +6. Security Considerations + + The points raised below are in addition to the general security + considerations for extended Internet fax [5], and others discussed in + [2,8,11,12,13] + +6.1 Capability descriptions and mechanisms + + Negotiation mechanisms reveal information about one party to other + parties. This may raise privacy concerns, and may allow a malicious + party to make better guesses about the presence of specific security + holes. + + Most of these concerns pertain to capability information getting into + the hands of someone who may abuse it. This document specifies + capabilities that help a sender to determine what image + characteristics can be processed by the recipient, not mechanisms for + their publication. Implementers and users should take care that the + mechanisms employed ensure that capabilities are revealed only to + appropriate persons, systems and agents. + +6.2 Specific threats + + 1. Unsolicited bulk mail: if it is known that a recipient can + process certain types of images, they may be targeted by bulk + mailers that want to send such images. + + + +Klyne & McIntyre Standards Track [Page 21] + +RFC 2879 Content Feature Schema for Internet Fax (V2) August 2000 + + +7. Acknowledgements + + The authors gratefully acknowledge the contributions of the following + persons who commented on earlier versions of this memo: James + Rafferty, Dan Wing, Robert Buckley, Mr Ryuji Iwazaki. The following + contributed ideas upon which some of the features described here have + been based: Larry Masinter, Al Gilman, Koen Holtman. + +8. References + + [1] Holtman, K., Mutz, A. and T. Hardie, "Media Feature Tag + Registration Procedure", RFC 2506, March 1999. + + [2] Klyne, G., "A syntax for describing media feature sets", RFC + 2533, March 1999. + + [3] Masinter, L., Holtman, K., Mutz, A. and D. Wing, "Media Features + for Display, Print, and Fax", RFC 2534, March 1999. + + [4] McIntyre, L. and G. Klyne, "Internet Fax T.30 Feature Mapping", + RFC 2880, July 2000. + + [5] Masinter, L. and D. Wing, RFC 2532, "Extended Facsimile Using + Internet Mail", RFC 2532, March 1999. + + [6] "Procedures for document facsimile transmission in the general + switched telephone network", ITU-T Recommendation T.30 (1999), + International Telecommunications Union, March 1999 + + [7] McIntyre, L., Buckley, R., Venable, D., Zilles, S., Parsons, G. + and J. Rafferty, "File format for Internet fax", RFC 2301, March + 1998. + + [8] Toyoda, K., Ohno, H., Murai, J. and D. Wing, "A Simple Mode of + Facsimile Using Internet Mail", RFC 2305, March 1998. + + [9] "Continuous-tone color representation method for facsimile" + ITU-T Recommendation T.42 (1996) International + Telecommunications Union (Covers custom illuminant, gamut) + + [10] "Colour and gray-scale image representation using lossless + coding scheme for facsimile" ITU-T Recommendation T.43 (1997) + International Telecommunications Union. (Covers JBIG for + colour/grey images) + + [12] Klyne, G., "Protocol-independent Content Negotiation Framework", + RFC 2703, September 1999. + + + + +Klyne & McIntyre Standards Track [Page 22] + +RFC 2879 Content Feature Schema for Internet Fax (V2) August 2000 + + + [13] "Standardization of Group 3 facsimile terminals for document + transmission", ITU-T Recommendation T.4 (1999), International + Telecommunications Union, (Covers basic fax coding formats: MH, + MR) + + [14] "Facsimile coding schemes and coding control functions for Group + 4 facsimile apparatus", ITU Recommendation T.6, International + Telecommunications Union, (Commonly referred to as the MMR + standard; covers extended 2-D fax coding format). + + [15] "Mixed Raster Content (MRC)", ITU-T Recommendation T.44, + International Telecommunications Union. + + [16] "Information technology - Digital compression and coding of + continuous-tone still image - Requirements and guidelines" ITU-T + Recommendation T.81 (1992) | ISO/IEC 10918-1:1993 International + Telecommunications Union, (Commonly referred to as JPEG + standard) + + [17] "Information technology - Coded representation of picture and + audio information - Progressive bi-level image compression" + ITU-T Recommendation T.82 (1993) | ISO/IEC 11544:1993 + International Telecommunications Union (Commonly referred to as + JBIG1 standard) + + [18] "Application profile for Recommendation T.82 - Progressive bi- + level image compression (JBIG1 coding scheme for facsimile + apparatus)", ITU-T Recommendation T.85 (1995),International + Telecommunications Union, (Covers bi-level JBIG). + + [19] "Colorimeter, 2nd ed.", CIE Publication No. 15.2, 1986. (Defines + CIELAB color space; use with fax is further constrained by T.42 + [9].) + + [20] Tag Image File Format, Revision 6.0 Adobe Developers Association + <ftp://ftp.adobe.com/pub/adobe/devrelations/devtechnotes/pdffiles + /tiff6.pdf> June 1992 + + [21] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA + Considerations Section in RFCs", BCP 26, RFC 2434, October 1998. + + [22] Klyne, G. and L. McIntyre, "Content feature schema for Internet + fax", RFC 2531, March 1999. + + + + + + + + +Klyne & McIntyre Standards Track [Page 23] + +RFC 2879 Content Feature Schema for Internet Fax (V2) August 2000 + + +9. Authors' Addresses + + Graham Klyne + Content Technologies Ltd. + 1220 Parkview, + Arlington Business Park + Theale + Reading, RG7 4SA + United Kingdom. + + Phone: +44 118 930 1300 + Fax: +44 118 930 1301 + EMail: GK@ACM.ORG + + + Lloyd McIntyre + Xerox Corporation + Mailstop PAHV-121 + 3400 Hillview Ave. + Palo Alto, CA 94304 USA + + Phone: +1-650-813-6762 + Fax: +1-650-845-2340 + EMail: Lloyd.McIntyre@pahv.xerox.com + + + + + + + + + + + + + + + + + + + + + + + + + + + +Klyne & McIntyre Standards Track [Page 24] + +RFC 2879 Content Feature Schema for Internet Fax (V2) August 2000 + + +Appendix A: Feature registrations + +A.1 Image size + + - Media Feature tag name(s): + + size-x + size-y + + - ASN.1 identifiers associated with these feature tags: + + size-x: 1.3.6.1.8.1.7 + size-y: 1.3.6.1.8.1.8 + + - Summary of the media features indicated: + + These feature tags indicate the size of a displayed, printed + or otherwise rendered document image; they indicate + horizontal (size-x) and vertical (size-y) dimensions. + + The unit of measure is inches (to be consistent with the + measure of resolution defined by the feature tag 'dpi'). + + Where the actual size is available in millimetres, a + conversion factor of 10/254 may be applied to yield an exact + inch-based value. + + - Values appropriate for use with these feature tags: + + Rational (>0) + + - The feature tag is intended primarily for use in the following + applications, protocols, services, or negotiation mechanisms: + + Print and display applications where different media choices + will be made depending on the size of the recipient device. + + - Examples of typical use: + + This example describes the maximum scanned image width and + height for Group 3 fax: 215x297 mm (8.46x11.69 inches): + + (size-x<=2150/254) + (size-y<=2970/254) + + + + + + + +Klyne & McIntyre Standards Track [Page 25] + +RFC 2879 Content Feature Schema for Internet Fax (V2) August 2000 + + + - Related standards or documents: + + The memo "Media Features for Display, Print, and Fax" [3] + describes features (pix-x, pix-y) for measuring document size + in pixels. + + Fax applications should declare physical dimensions using the + features defined here. + + - Considerations particular to use in individual applications, + protocols, services, or negotiation mechanisms: + + Where no physical size is known or available, but a pixel size + is known, a notional size should be declared based upon known + pixel dimensions and a notional resolution of (say) 100dpi + + For example, to describe a 640x480 pixel display: + + (& (size-x<=640/100) (size-y<=480/100) (dpi=100) ) + + The notional 100dpi resolution is used as it represents a + fairly typical resolution for a pixel-limited display. + Reducing the rational numbers to canonical form gives the + following equivalent expression: + + (& (size-x<=32/5) (size-y<=24/5) (dpi=100) ) + + - Interoperability considerations: + + For interoperability with other (non-fax) applications that + use only pixel-based measurements, pixel dimensions (pix-x, + pix-y) may be declared in addition to physical measurements. + + - Related feature tags: + + pix-x [3] + pix-y [3] + dpi [3] + dpi-xyratio [this document] + + - Intended usage: + + Common + + + + + + + + +Klyne & McIntyre Standards Track [Page 26] + +RFC 2879 Content Feature Schema for Internet Fax (V2) August 2000 + + + - Author/Change controller: + + IETF + +A.2 Resolution aspect ratio + + - Media Feature tag name(s): + + dpi-xyratio + + - ASN.1 identifier associated with this feature tag: + + 1.3.6.1.8.1.9 + + - Summary of the media features indicated: + + This feature is used to indicate differential horizontal and + vertical resolution capability. In the absence of this + feature, horizontal and vertical resolutions are presumed to + be the same. + + When this feature tag is specified, any declared resolution + (dpi) is presumed to apply to the horizontal axis, and the + vertical resolution is obtained by dividing that declared + resolution by the resolution ratio. + + The value of this feature is a pure number, since it + represents the ratio of two resolution values. + + - Values appropriate for use with this feature tag: + + Rational (>0) + + - The feature tag is intended primarily for use in the following + applications, protocols, services, or negotiation mechanisms: + + Internet fax, and other print or display applications that + must handle differential horizontal and vertical resolution + values. + + - Examples of typical use: + + The following example describes a fax resolution of 204 dpi + horizontally by 391 dpi vertically: + + (& (dpi=204) (dpi-xyratio=204/391) ) + + + + + +Klyne & McIntyre Standards Track [Page 27] + +RFC 2879 Content Feature Schema for Internet Fax (V2) August 2000 + + + - Related standards or documents: + + The memo "Media Features for Display, Print, and Fax" [3] + describes a feature (dpi) for measuring document resolution. + + - Interoperability considerations: + + When interoperating with an application that does not + recognize the differential resolution feature, resolution + matching may be performed on the basis of the horizontal + resolution only, so aspect ratio information may be lost. + + - Related feature tags: + + dpi [3] + size-x [this document] + size-y [this document] + + - Intended usage: + + Internet fax + + - Author/Change controller: + + IETF + +A.3 Color levels + + - Media Feature tag name(s): + + color-levels + + - ASN.1 identifier associated with this feature tag: + + 1.3.6.1.8.1.10 + + - Summary of the media features indicated: + + This feature tag is used to indicate a number of different + image data pixel color values. + + When mapped (palletized) color is used, this is generally + different from the number of different colors that can be + represented through the color mapping function. + + This feature tag is used in conjunction with a 'color' feature + having a value other than 'Binary'. + + + + +Klyne & McIntyre Standards Track [Page 28] + +RFC 2879 Content Feature Schema for Internet Fax (V2) August 2000 + + + - Values appropriate for use with this feature tag: + + Integer (>=2) + + - The feature tag is intended primarily for use in the following + applications, protocols, services, or negotiation mechanisms: + + Color image printing or display applications where the data + resource used may depend upon color handling capabilities of + the recipient. + + - Examples of typical use: + + To describe recipient capabilities: + (& (color=limited) (color-levels<=6) ) + (& (color=grey) (color-levels<=64) ) + (& (color=mapped) (color-levels<=240) ) + (& (color=full) (color-levels<=16777216) ) + + To describe capabilities used by a document: + (& (color=limited) (color-levels=4) ) + (& (color=grey) (color-levels=48) ) + (& (color=mapped) (color-levels=100) ) + (& (color=full) (color-levels=32768) ) + + - Related standards or documents: + + The memo "Media Features for Display, Print, and Fax" [3] + describes a feature (color) for indicating basic color + capabilities. + + - Interoperability considerations: + + The actual number of color values used by a document does not, + in general, exactly match the number that can be handled by a + recipient. To achieve a feature match, at least one must be + declared as an inequality (i.e. not both as equalities). + + It is recommended that a recipient declares the number of + color values that it can handle as an inequality (<=), and a + data resource declares the number of colors that it uses with + an equality, as shown in the examples above. + + + + + + + + + +Klyne & McIntyre Standards Track [Page 29] + +RFC 2879 Content Feature Schema for Internet Fax (V2) August 2000 + + + - Security considerations: + + - Privacy concerns, related to exposure of personal information: + Where feature matching is used to select content applicable + to the physical abilities of a user, unusual values for this + feature tag might give an indication of a user's restricted + abilities. + + - Related feature tags: + + color [3] + color-space [this document] + + - Intended usage: + + Internet fax + Color image scanning/rendering applications + + - Author/Change controller: + + IETF + +A.4 Color space + + - Media Feature tag name(s): + + color-space + + - ASN.1 identifier associated with this feature tag: + + 1.3.6.1.8.1.11 + + - Summary of the media features indicated: + + This feature indicates a color space. + + A color space value provides two types of information: + o the color model used to represent a color value, including + the number of color components + o a mapping between color values and their physical + realizations + + Device color space values are defined for applications where + the general color representation used is significant, but + exact color rendering is left to the device used. Device + color spaces defined here have values of the form 'Device- + xxx'. + + + + +Klyne & McIntyre Standards Track [Page 30] + +RFC 2879 Content Feature Schema for Internet Fax (V2) August 2000 + + + Calibrated color space values are provided for use with a + rendering system that is calibrated with respect to some + indicated definition, and capable of processing device- + independent color information accordingly. + + - Values appropriate for use with this feature tag: + + Token + + Device color Device-RGB (device dependent RGB) + spaces: Device-CMY (device dependent CMY) + Device-CMYK (device dependent CMYK) + + Calibrated color CIELAB (per T.42 [9]) + space: + + (may be extended by further registrations) + + 'Color-space=CIELAB' indicates the CIE L*a*b* colour space, + using CIED50 illuminant and its perfectly diffuse reflecting + white point (per T.42 [9]). + + - The feature tag is intended primarily for use in the following + applications, protocols, services, or negotiation mechanisms: + + Color image printing and display applications where the data + resource used may depend upon color handling capabilities of + the recipient. + + Scanning applications where the data transferred may depend + upon the image generation capabilities of the originator. + + - Examples of typical use: + + To describe rendering or scanning capabilities: + + (color-space=[Device-RGB,CIELAB]) + + To describe capabilities assumed by a document for which + approximate color reproduction is required: + + (color-space=Device-RGB) + + To describe capabilities assumed by a document for which exact + color reproduction is required: + + (color-space=CIELAB) + + + + +Klyne & McIntyre Standards Track [Page 31] + +RFC 2879 Content Feature Schema for Internet Fax (V2) August 2000 + + + - Related standards or documents: + + CIELAB color space is defined in [19] + + CIELAB use for fax is described in ITU T.42 [9] + + - Interoperability considerations: + + A color-handling receiver should indicate any appropriate + device color space capability, in addition to any calibrated + color spaces that it may support. + + Calibrated color spaces are intended to be used when precise + color matching is required; otherwise, if applicable, a + device color space (color-space=Device-xxx) should be + indicated. + + Documents for which exact color matching is not important + should indicate a device color space capability, if + applicable. + + These principles allow sender/receiver feature matching to be + achieved when exact color matching is not required. + + - Security considerations: + + - Privacy concerns, related to exposure of personal information: + Where feature matching is used to select content applicable + to the physical abilities of a user, unusual values for this + feature tag might give an indication of a user's restricted + abilities. + + - Denial of service concerns related to consequences of + specifying incorrect values: + Failure to indicate a generic color space capability for a + device may lead to failure to match color space for an + application or document that does not require an exact color + match. + + - Related feature tags: + + color [3] + + - Related media types or data formats: + + TIFF-FX [7] + + + + + +Klyne & McIntyre Standards Track [Page 32] + +RFC 2879 Content Feature Schema for Internet Fax (V2) August 2000 + + + - Intended usage: + + Internet fax + Color image scanning/rendering applications + + - Author/Change controller: + + IETF + +A.5 CIELAB color illuminant + + - Media Feature tag name(s): + + color-illuminant + + - ASN.1 identifier associated with this feature tag: + + 1.3.6.1.8.1.29 + + - Summary of the media features indicated: + + This feature indicates a color illuminant. This has the + effect of modifying the color space calibration to reflect the + use of different sources of illumination. + + A color-illuminant value would normally be used only with a + calibrated color space. + + - Values appropriate for use with this feature tag: + + Token + + CIELAB illuminant D50 + values: D65 + D75 + SA + SC + F2 + F7 + F11 + + Defined by color CTnnnn where 'nnnn' is a decimal + temperature: representation of the illuminant + color temperature in Kelvins. + + (may be extended by further registrations) + + + + + +Klyne & McIntyre Standards Track [Page 33] + +RFC 2879 Content Feature Schema for Internet Fax (V2) August 2000 + + + NOTE: The default color illuminant for Group 3 fax is D50. + + - The feature tag is intended primarily for use in the following + applications, protocols, services, or negotiation mechanisms: + + Color image printing and display applications where the data + resource used may depend upon detailed color handling + capabilities of the recipient. + + Scanning applications where the data transferred may depend + upon the image generation capabilities of the originator. + + - Examples of typical use: + + To describe rendering or scanning capabilities, or to describe + capabilities assumed by a document for which exact color + handling capabilities are required: + + (& (color-space=CIELAB) (color-illuminant=D50) ) + + - Related standards or documents: + + CIELAB color illuminant representations are described in ITU + T.4 [13], Annex E.6.7. + + - Interoperability considerations: + + A color-handling receiver that supports a calibrated color + space should indicate any constraint on the illuminants it can + handle. + + In the absence of a color-illuminant constraint, a receiver is + presumed to accept and deal with any specified illuminant + value. + + - Related feature tags: + + color [3] + color-space [this document] + + - Related media types or data formats: + + TIFF-FX [7] + + - Intended usage: + + Internet fax + Color image scanning/rendering applications + + + +Klyne & McIntyre Standards Track [Page 34] + +RFC 2879 Content Feature Schema for Internet Fax (V2) August 2000 + + + - Author/Change controller: + + IETF + +A.6 CIELAB color depth + + - Media Feature tag name(s): + + CIELAB-L-depth + CIELAB-a-depth + CIELAB-b-depth + + - ASN.1 identifiers associated with these feature tags: + + CIELAB-L-depth: 1.3.6.1.8.1.12 + CIELAB-a-depth: 1.3.6.1.8.1.13 + CIELAB-b-depth: 1.3.6.1.8.1.14 + + - Summary of the media features indicated: + + These feature tags indicate a color depth capability; i.e. + the level of detail to which an individual CIELAB color + component can be specified. They define the number of + distinct values possible for each of the color components L*, + a* and b*. + + Typically, this feature would be used with 'color=mapped', and + possibly 'color=grey' or 'color=full', to indicate the number + of distinct colors that can be represented. + + NOTE: this feature tag describes the number of values that + can be represented for a color component, and does not + necessarily indicate the number of distinct values that can + be rendered or resolved by a system. + + - Values appropriate for use with these feature tags: + + Integer (>0) + + - These feature tags are intended primarily for use in the + following applications, protocols, services, or negotiation + mechanisms: + + Color image printing and display applications where the data + resource used may depend upon color handling capabilities of + the recipient. + + + + + +Klyne & McIntyre Standards Track [Page 35] + +RFC 2879 Content Feature Schema for Internet Fax (V2) August 2000 + + + Scanning applications where the data transferred may depend + upon the image generation capabilities of the originator. + + - Examples of typical use: + + To describe rendering or scanning capabilities: + + (& (color=mapped) (color-levels<=240) + (CIELAB-L-depth<=128) + (CIELAB-a-depth<=128) + (CIELAB-b-depth<=128) ) + (& (color=full) (color-levels<=16777216) + (CIELAB-L-depth<=256) + (CIELAB-a-depth<=128) + (CIELAB-b-depth<=128) ) + + To describe capabilities assumed by a document: + + (& (color=mapped) (color-levels=200) + (CIELAB-L-depth=32) + (CIELAB-a-depth=32) + (CIELAB-b-depth=32) ) + (& (color=full) (color-levels=32768) + (CIELAB-L-depth=128) + (CIELAB-a-depth=32) + (CIELAB-b-depth=32) ) + + - Related standards or documents: + + The memo "Media Features for Display, Print, and Fax" [3] + defines a feature (color) for indicating basic color + capabilities. + CIELAB color space is defined in [19] + + CIELAB use for fax is described in ITU T.42 [9] + + - Related feature tags: + + color [3] + color-levels [this document] + color-space [this document] + + - Intended usage: + + Internet fax + Color image scanning/rendering applications + + + + + +Klyne & McIntyre Standards Track [Page 36] + +RFC 2879 Content Feature Schema for Internet Fax (V2) August 2000 + + + - Author/Change controller: + + IETF + +A.7 CIELAB color gamut + + - Media Feature tag name(s): + + CIELAB-L-min + CIELAB-L-max + CIELAB-a-min + CIELAB-a-max + CIELAB-b-min + CIELAB-b-max + + - ASN.1 identifiers associated with these feature tags: + + CIELAB-L-min: 1.3.6.1.8.1.15 + CIELAB-L-max: 1.3.6.1.8.1.16 + CIELAB-a-min: 1.3.6.1.8.1.17 + CIELAB-a-max: 1.3.6.1.8.1.18 + CIELAB-b-min: 1.3.6.1.8.1.19 + CIELAB-b-max: 1.3.6.1.8.1.20 + + - Summary of the media features indicated: + + These feature indicate a supported range of color values, by + indicating minimum and maximum values used for each color + component in a CIELAB color space. + + 'CIELAB-L-min' and 'CIELAB-L-max' are the minimum and maximum + values of the L* component. + + 'CIELAB-a-min' and 'CIELAB-a-max' are the minimum and maximum + values of the a* component. + + 'CIELAB-b-min' and 'CIELAB-b-max' are the minimum and maximum + values of the b* component. + + NOTE: color component values are assumed to be rational + numbers, so a limited gamut does not necessarily indicate + limited color resolution. + + - Values appropriate for use with this feature tag: + + Rational + + + + + +Klyne & McIntyre Standards Track [Page 37] + +RFC 2879 Content Feature Schema for Internet Fax (V2) August 2000 + + + - The feature tag is intended primarily for use in the following + applications, protocols, services, or negotiation mechanisms: + + Color image printing and display applications where the data + resource used may depend upon detailed color handling + capabilities of the recipient. + + Scanning applications where the data transferred may depend + upon the detailed color image generation capabilities of the + originator. + + - Examples of typical use: + + To describe rendering or scanning capabilities: + + (& (CIELAB-L-min>=0) + (CIELAB-L-max<=100) + (CIELAB-a-min>=-75) + (CIELAB-a-max<=+75) + (CIELAB-b-min>=-85) + (CIELAB-b-max<=+85) ) + + To describe capabilities required by a document: + + (& (CIELAB-L-min=20) + (CIELAB-L-max=80) + (CIELAB-a-min=-35) + (CIELAB-a-max=+55) + (CIELAB-b-min=-45) + (CIELAB-b-max=+65) ) + + - Related standards or documents: + + CIELAB color space is defined in [19] + + CIELAB use for fax is described in ITU T.42 [9] + + - Interoperability considerations: + + When describing a recipient's capabilities, the minimum and + maximum color component values that can be rendered should be + indicated by inequalities as shown in the examples above. + + When describing a document, the actual minimum and maximum + color component values used should be indicated, as shown + above. + + + + + +Klyne & McIntyre Standards Track [Page 38] + +RFC 2879 Content Feature Schema for Internet Fax (V2) August 2000 + + + - Security considerations: + + - Privacy concerns, related to exposure of personal information: + Where feature matching is used to select content applicable + to the physical abilities of a user, unusual values for this + feature tag might give an indication of a user's restricted + abilities. + + - Related feature tags: + + color [3] + color-space [this document] + + - Related media types or data formats: + + TIFF-FX [7] + + - Intended usage: + + Internet fax + Color image scanning/rendering applications + + - Author/Change controller: + + IETF + +A.8 Image file structure + + - Media Feature tag name(s): + + image-file-structure + + - ASN.1 identifier associated with this feature tag: + + 1.3.6.1.8.1.21 + + - Summary of the media features indicated: + + This feature indicates a file structure used for transfer and + presentation of image data. + + It does not indicate image data coding: that is described by + separate feature tags (image-coding, etc.). + + + + + + + + +Klyne & McIntyre Standards Track [Page 39] + +RFC 2879 Content Feature Schema for Internet Fax (V2) August 2000 + + + - Values appropriate for use with this feature tag: + + Token + + Image file TIFF + structure TIFF-limited + options: TIFF-minimal + TIFF-MRC + TIFF-MRC-limited + + (may be extended by further registrations, + to cover non-TIFF image file structures) + + - The feature tag is intended primarily for use in the following + applications, protocols, services, or negotiation mechanisms: + + Internet fax, and other print or display applications that + transfer image data. + + - Examples of typical use: + + See Appendix B of this memo. + + - Considerations particular to use in individual applications, + protocols, services, or negotiation mechanisms: + + This tag is intended to provide information about an image + file structure. Information about image data coding is + provided by other tags. + + The following tag values are defined here: + + o 'TIFF' indicates image data enclosed and tagged using TIFF + structures described in Adobe's definition of TIFF [20]. + + o 'TIFF-limited' indicates image data structured using TIFF, + but with limitations on the placement of Image File + Descriptors (IFDs) within the file, which are indicated in + section 4.4.6 of RFC 2301 [7]. + + o 'TIFF-minimal' indicates a TIFF image format that meets the + IFD placement, byte ordering and bit ordering requirements + of the "minimal black and white mode" described in section + 3.5 of RFC 2301 [7], also known as TIFF-S. + + + + + + + +Klyne & McIntyre Standards Track [Page 40] + +RFC 2879 Content Feature Schema for Internet Fax (V2) August 2000 + + + o 'TIFF-MRC' uses a TIFF image structure [20] augmented with a + sub-IFD structure, described for the "Mixed Raster Content + mode" in section 8.1.2 of RFC 2301 [7], also known as TIFF-M + (see also tag 'MRC-mode'). + + o 'TIFF-MRC-limited' is the same as 'TIFF-MRC', except that + the IFD placement is constrained as for 'TIFF-limited'. + + Registration of additional image file structure tags should + focus similarly on image file structure issues, not raw image + data compression and coding. As a guide, an image file + structure may contain image data coded in a variety of ways, + and carries information to describe that coding separately + from MIME content-type labelling, etc. + + - Related feature tags: + + image-coding [this document] + MRC-mode [this document] + + - Related media types or data formats: + + TIFF-FX [7] + TIFF V6.0 (Adobe) [20] + + - Intended usage: + + Internet fax + Image scanning/rendering applications + + - Author/Change controller: + + IETF + +A.9 Image data coding + + - Media Feature tag name(s): + + image-coding + + - ASN.1 identifier associated with this feature tag: + + 1.3.6.1.8.1.22 + + - Summary of the media features indicated: + + This feature tag indicates a form of image data compression + and coding used. + + + +Klyne & McIntyre Standards Track [Page 41] + +RFC 2879 Content Feature Schema for Internet Fax (V2) August 2000 + + + It identifies a generic image coding technique used, without + regard to any specific profiling of that technique that may be + applied. Values for this feature are generally applicable + across a wide range of image transfer applications. + + This information is distinct from the image file structure and + MRC information conveyed by the 'image-file-structure' tags. + + - Values appropriate for use with this feature tag: + + Token MH + MR + MMR + JBIG + JPEG + + (may be extended by further registrations) + + - The feature tag is intended primarily for use in the following + applications, protocols, services, or negotiation mechanisms: + + Internet fax, and other applications that transfer image data. + + - Examples of typical use: + + See Appendix B of this memo. + + - Related standards or documents: + + MH, MR: ITU T.4 [13] + MMR: ITU T.6 [14] + JPEG: ITU T.81 [16] + JBIG: ITU T.82 [17] + + - Interoperability considerations: + + To establish the correct conditions for interoperability + between systems, capabilities to handle the generic image + coding technique and the specific image coding constraints + must be established. + + - Related feature tags: + + image-coding-constraint [this document] + JBIG-stripe-size [this document] + image-interleave [this document] + + + + + +Klyne & McIntyre Standards Track [Page 42] + +RFC 2879 Content Feature Schema for Internet Fax (V2) August 2000 + + + - Related media types or data formats: + + TIFF-FX [7] + + - Intended usage: + + Internet fax + Image scanning/rendering applications + + - Author/Change controller: + + IETF + +A.10 Image coding constraint + + - Media Feature tag name(s): + + image-coding-constraint + + - ASN.1 identifier associated with these feature tags: + + 1.3.6.1.8.1.23 + + - Summary of the media features indicated: + + This feature tag qualifies the 'image-coding' feature with a + specific profile or usage constraints. + + Values for this feature are generally specific to some given + value of 'image-coding' and also to some restricted + application or class of applications. + + - Values appropriate for use with this feature tag: + + Token JBIG-T85 (bi-level, per ITU T.85) + JBIG-T43 (multi-level, per ITU T.43) + JPEG-T4E (per ITU T.4, Annex E) + + (may be extended by further registrations) + + - The feature tag is intended primarily for use in the following + applications, protocols, services, or negotiation mechanisms: + + Internet fax, and other applications that transfer image data. + + The specific values for this feature indicated above are + intended for use with Internet fax. + + + + +Klyne & McIntyre Standards Track [Page 43] + +RFC 2879 Content Feature Schema for Internet Fax (V2) August 2000 + + + - Examples of typical use: + + See Appendix B of this memo. + + - Related standards or documents: + + JBIG-T85: ITU T.85 [18] + JBIG-T43: ITU T.43 [10] + JPEG-T4E: ITU T.4 Annex E [13] + + - Interoperability considerations: + + To establish the correct conditions for interoperability + between systems, capabilities to handle the generic image + coding technique and the specific image coding constraints + must be established. + + - Related feature tags: + + image-coding [this document] + JBIG-stripe-size [this document] + image-interleave [this document] + + - Related media types or data formats: + + TIFF-FX [7] + + - Intended usage: + + Internet fax + Color image scanning/rendering applications + + - Author/Change controller: + + IETF + +A.11 JBIG stripe size + + - Media Feature tag name(s): + + JBIG-stripe-size + + - ASN.1 identifier associated with these feature tags: + + 1.3.6.1.8.1.24 + + + + + + +Klyne & McIntyre Standards Track [Page 44] + +RFC 2879 Content Feature Schema for Internet Fax (V2) August 2000 + + + - Summary of the media features indicated: + + This feature is a specific usage constraint that is applied to + JBIG image coding (image-coding=JBIG), and indicates the + allowable size for each stripe of an image, except the last. + + A stripe of a JBIG image is a delimited horizontal band of + compressed image data that can be decompressed separately from + the surrounding data. + + - Values appropriate for use with this feature tag: + + Integer (>0) + + - The feature tag is intended primarily for use in the following + applications, protocols, services, or negotiation mechanisms: + + Internet fax, and other applications that transfer image data. + + - Examples of typical use: + + (JBIG-stripe-size=128) + (JBIG-stripe-size>0) + + - Related standards or documents: + + JBIG: ITU T.82 [17] + JBIG-T85: ITU T.85 [18] + JBIG-T43: ITU T.43 [10] + + - Considerations particular to use in individual applications, + protocols, services, or negotiation mechanisms: + + In the case of Internet fax, the specific constraints allowed + for a receiver are those given as examples above. + + Specifying a stripe size that is not limited (JBIG-stripe- + size>0) means that an entire page of image data is encoded as + a single unit. This may place considerable demands on the + memory of a receiving system, as the entire stripe needs to be + buffered in memory. + + - Interoperability considerations: + + To establish the correct conditions for interoperability + between systems, capabilities to handle the generic image + coding technique and the specific image coding constraints + must be established. + + + +Klyne & McIntyre Standards Track [Page 45] + +RFC 2879 Content Feature Schema for Internet Fax (V2) August 2000 + + + - Related feature tags: + + image-coding [this document] + image-coding-constraint [this document] + image-interleave [this document] + + - Related media types or data formats: + + TIFF-FX [7] + + - Intended usage: + + Internet fax + Color image scanning/rendering applications + + - Author/Change controller: + + IETF + +A.12 Image interleave + + - Media Feature tag name(s): + + image-interleave + + - ASN.1 identifier associated with this feature tag: + + 1.3.6.1.8.1.25 + + - Summary of the media features indicated: + + This feature indicates an image interleave capability. + + It may be used with JBIG images (image-coding=JBIG) to + indicate color plane interleaving of either stripes or entire + image planes. + + - Values appropriate for use with this feature tag: + + Token Stripe + Plane + + - The feature tag is intended primarily for use in the following + applications, protocols, services, or negotiation mechanisms: + + Internet fax, and other applications that transfer image data. + + + + + +Klyne & McIntyre Standards Track [Page 46] + +RFC 2879 Content Feature Schema for Internet Fax (V2) August 2000 + + + - Examples of typical use: + + (image-interleave=stripe) + (image-interleave=[stripe,plane]) + + - Considerations particular to use in individual applications, + protocols, services, or negotiation mechanisms: + + Specifying a plane interleave means that an entire page of + image data must be buffered in order to generate or render the + image. This may place considerable demands on the memory of a + sending or receiving system. + + - Related feature tags: + + image-coding [this document] + JBIG-stripe-size [this document] + + - Related media types or data formats: + + TIFF-FX [7] + + - Intended usage: + + Internet fax + Color image scanning/rendering applications + + - Author/Change controller: + + IETF + +A.13 Color subsampling + + - Media Feature tag name(s): + + color-subsampling + + - ASN.1 identifier associated with this feature tag: + + 1.3.6.1.8.1.26 + + - Summary of the media features indicated: + + This feature tag indicates whether color information may be + subsampled with respect to luminance data. + + + + + + +Klyne & McIntyre Standards Track [Page 47] + +RFC 2879 Content Feature Schema for Internet Fax (V2) August 2000 + + + It is used with continuous color images (color=full), color + spaces that use separate luminance and color components + (e.g. color-space=LAB), and image file structures that support + color subsampling. + + - Values appropriate for use with this feature tag: + + String "1:1:1" + This value indicates a full set of color + component samples for each luminance + component sample. + + "4:1:1" + This value indicates one set of color component + samples for each 4 luminance samples. + + (may be extended by further registrations) + + - The feature tag is intended primarily for use in the following + applications, protocols, services, or negotiation mechanisms: + + Color image printing and display applications where the data + resource used may depend upon color handling capabilities of + the recipient. + + Scanning applications where the data transferred may depend + upon the image generation capabilities of the originator. + + - Examples of typical use: + + (& (color=full) (color-space=[LAB,CIELAB]) + (color-subsampling=["1:1:1","4:1:1"]) ) + + - Related feature tags: + + color [3] + color-space [this document] + image-file-structure [this document] + + - Related media types or data formats: + + TIFF-FX [7] + + - Intended usage: + + Internet fax + Color image scanning/rendering applications + + + + +Klyne & McIntyre Standards Track [Page 48] + +RFC 2879 Content Feature Schema for Internet Fax (V2) August 2000 + + + - Author/Change controller: + + IETF + +A.14 MRC availability and mode + + - Media Feature tag name(s): + + MRC-mode + + - ASN.1 identifier associated with this feature tag: + + 1.3.6.1.8.1.27 + + - Summary of the media features indicated: + + This feature is used to indicate the availability of MRC + (mixed raster content) image format capability, and also the + MRC mode available. A zero value indicates MRC is not + available, a non-zero value (in the range 1..7) indicates the + available MRC mode number. + + An MRC formatted document is actually a collection of several + images, each of which is described by a separate feature + collection. An MRC-capable receiver is presumed to be capable + of accepting any combination of contained images that conform + to the MRC construction rules, where each such image matches + the separately declared resolution, color capability, color + model, image coding, and any other capabilities. + + NOTE: an MRC formatted document may appear within a + TIFF image file structure. + + Within an MRC-formatted document, multi-level coders + are used for foreground and background images (i.e. + odd-numbered layers: 1, 3, 5, etc.) and bi-level coders + are used for mask layers (i.e. even numbered layers 2, + 4, 6, etc.). + + - Values appropriate for use with this feature tag: + + Integer (0..7) + + + + + + + + + +Klyne & McIntyre Standards Track [Page 49] + +RFC 2879 Content Feature Schema for Internet Fax (V2) August 2000 + + + - The feature tag is intended primarily for use in the following + applications, protocols, services, or negotiation mechanisms: + + Internet fax, and other applications that transfer image data. + + - Examples of typical use: + + See Appendix B of this document. + + - Related standards or documents: + + ITU T.44 [15] + + - Interoperability considerations: + + To establish the correct conditions for interoperability + between systems, capabilities to handle the MRC mode and any + contained image coding techniques must be established. + + - Related feature tags: + + image-coding [this document] + MRC-max-stripe-size [this document] + + - Related media types or data formats: + + TIFF-FX [7] + + - Intended usage: + + Internet fax + Color image scanning/rendering applications + + - Author/Change controller: + + IETF + +A.15 MRC maximum stripe size + + - Media Feature tag name(s): + + MRC-max-stripe-size + + - ASN.1 identifier associated with this feature tag: + + 1.3.6.1.8.1.28 + + + + + +Klyne & McIntyre Standards Track [Page 50] + +RFC 2879 Content Feature Schema for Internet Fax (V2) August 2000 + + + - Summary of the media features indicated: + + This feature may be used with MRC coding (MRC-mode>=1), and + indicates the maximum number of scan lines in each MRC stripe. + + The value given indicates an upper bound on the stripe size. + The actual value may vary between stripes, and the actual size + for each stripe is indicated in the image data. + + - Values appropriate for use with this feature tag: + + Integer (>0) + + - The feature tag is intended primarily for use in the following + applications, protocols, services, or negotiation mechanisms: + + Internet fax, and other applications that transfer image data. + + - Examples of typical use: + + (MRC-max-stripe-size<=256) + (MRC-max-stripe-size>=0) + + - Considerations particular to use in individual applications, + protocols, services, or negotiation mechanisms: + + For Internet fax, the legal constraints for an image receiver + are those given as examples above. + + - Related feature tags: + + MRC-mode [this document] + + - Related media types or data formats: + + TIFF-FX [7] + + - Intended usage: + + Internet fax + Color image scanning/rendering applications + + - Author/Change controller: + + IETF + + + + + + +Klyne & McIntyre Standards Track [Page 51] + +RFC 2879 Content Feature Schema for Internet Fax (V2) August 2000 + + +Appendix B: TIFF mode descriptions + + This appendix contains descriptions of the TIFF modes defined by + RFC 2301 [7], presented as feature set expressions in the form + defined by "A syntax for describing media feature sets" [2] and + using the feature schema introduced by this document. + + These may be taken as illustrations of the feature set combinations + that are required for the corresponding TIFF profiles described by + RFC 2301. + + TIFF-S has no optional elements, so is presented as a single + feature set. Other profiles are presented as (TIFF-x-base) and + (TIFF-x-full) indicating the minimum and full feature sets + associated with each profile. + + (TIFF-S) :- + (& (image-file-structure=TIFF-S) + (color=Binary) + (image-coding=MH) (MRC-mode=0) + (| (& (dpi=200) + (dpi-xyratio=[200/100,200/200]) + (size-x=1728/200) ) + (& (dpi=204) + (dpi-xyratio=[204/98,204/196] + (size-x=1728/204) ) ) + (paper-size=A4) ) + + (TIFF-F-base) :- + (& (image-file-structure=TIFF-F) + (color=Binary) + (image-coding=MH) (MRC-mode=0) + (dpi=204) + (dpi-xyratio=[204/98,204/196]) + (size-x=1728/204) + (paper-size=A4) ) + + (TIFF-F-full) :- + (& (image-file-structure=TIFF-F) + (color=Binary) + (image-coding=[MH,MR,MMR]) (MRC-mode=0) + (| (& (dpi=200) + (dpi-xyratio=[200/100,200/200]) + (size-x=[1728/200,2048/200,2432/200]) ) + (& (dpi=204) + (dpi-xyratio=[204/98,204/196,204/391]) + (size-x=[1728/204,2048/204,2432/204]) ) + (& (dpi=300) + + + +Klyne & McIntyre Standards Track [Page 52] + +RFC 2879 Content Feature Schema for Internet Fax (V2) August 2000 + + + (dpi-xyratio=300/300) + (size-x=[2592/300,3072/300,3648/300]) ) + (& (dpi=400) + (dpi-xyratio=400/400) + (size-x=[3456/400,4096/400,4864/400]) ) + (& (dpi=408) + (dpi-xyratio=408/391) + (size-x=[3456/408,4096/408,4864/408]) ) ) + (paper-size=[A4, B4, A3, letter, legal]) ) + + (TIFF-J-base) :- + (& (image-file-structure=TIFF-J) + (color=Binary) + (MRC-mode=0) + (image-coding=JBIG) + (image-coding-constraint=JBIG-T85) + (JBIG-stripe-size=128) + (dpi=204) + (dpi-xyratio=[204/98,204/196]) + (size-x=1728/204) + (paper-size=A4) ) + + (TIFF-J-full) :- + (& (image-file-structure=TIFF-J) + (color=Binary) + (MRC-mode=0) + (image-coding=JBIG) + (image-coding-constraint=JBIG-T85) + (JBIG-stripe-size>0) + (| (& (dpi=200) + (dpi-xyratio=[200/100,200/200]) + (size-x=[1728/200,2048/200,2432/200]) ) + (& (dpi=204) + (dpi-xyratio=[204/98,204/196,204/391]) + (size-x=[1728/204,2048/204,2432/204]) ) + (& (dpi=300) + (dpi-xyratio=300/300) + (size-x=[2592/300,3072/300,3648/300]) ) + (& (dpi=400) + (dpi-xyratio=400/400) + (size-x=[3456/400,4096/400,4864/400]) ) + (& (dpi=408) + (dpi-xyratio=408/391) + (size-x=[3456/408,4096/408,4864/408]) ) ) + (paper-size=[A4, B4, A3, letter, legal]) ) + + (TIFF-C-base) :- + (& (image-file-structure=TIFF-C) + + + +Klyne & McIntyre Standards Track [Page 53] + +RFC 2879 Content Feature Schema for Internet Fax (V2) August 2000 + + + (color=grey) + (color-levels<=256) + (MRC-mode=0) + (image-coding=JPEG) (image-coding-constraint=JPEG-T4E) + (color-space=CIELAB) + (CIELAB-L-depth<=101) + (CIELAB-L-min>=0) + (CIELAB-L-max<=100) + (color-illuminant=D50) + (dpi=200) (dpi-xyratio=1) + (size-x=864/100) + (paper-size=A4) ) + + (TIFF-C-full) :- + (& (image-file-structure=TIFF-C) + (image-coding=JPEG) (image-coding-constraint=JPEG-T4E) + (color-space=CIELAB) + (| (& (color=grey) + (color-levels<=4096) + (CIELAB-L-depth<=4096) ) + (& (color=full) + (color-levels<=68719476736) + (color-subsampling=["4:1:1","1:1:1"]) + (CIELAB-L-depth<=4096) + (CIELAB-a-depth<=4096) + (CIELAB-b-depth<=4096) ) ) + (MRC-mode=0) + (dpi=[100,200,300,400]) (dpi-xyratio=1) + (size-x=[864/100,1024/100,1216/100]) + (paper-size=[A4, B4, A3, letter, legal]) ) + + (TIFF-L-base) :- + (& (image-file-structure=TIFF-L) + (MRC-mode=0) + (image-coding=JBIG) + (image-coding-constraint=JBIG-T43) + (JBIG-stripe-size=128) + (image-interleave=stripe) + (color=grey) + (color-levels<=256) + (color-space=CIELAB) + (CIELAB-L-depth=101) + (CIELAB-L-min>=0) + (CIELAB-L-max<=100) + (color-illuminant=D50) + (dpi=200) (dpi-xyratio=1) + (size-x=864/100) + (paper-size=A4) ) + + + +Klyne & McIntyre Standards Track [Page 54] + +RFC 2879 Content Feature Schema for Internet Fax (V2) August 2000 + + + (TIFF-L-full) :- + (& (image-file-structure=TIFF-L) + (MRC-mode=0) + (image-coding=JBIG) + (image-coding-constraint=JBIG-T43) + (JBIG-stripe-size>0) + (image-interleave=[stripe, plane]) + (| (& (color=limited) + (color-levels<=8) + (color-space=[Device-RGB, Device-CMY] ) ) + (& (color=limited) + (color-levels<=16) + (color-space=Device-CMYK) ) + (& (color=mapped) + (color-levels<=65536) + (color-space=CIELAB) + (CIELAB-L-depth<=4096) + (CIELAB-a-depth<=4096) + (CIELAB-b-depth<=4096) ) + (& (color=grey) + (color-levels<=4096) + (color-space=CIELAB) + (CIELAB-L-depth<=4096) ) + (& (color=full) + (color-space=CIELAB) + (color-levels<=68719476736) + (CIELAB-L-depth<=4096) + (CIELAB-a-depth<=4096) + (CIELAB-b-depth<=4096) + (CIELAB-L-min>=0) ) ) + (dpi=[100,200,300,400]) (dpi-xyratio=1) + (size-x=[864/100,1024/100,1216/100]) + (paper-size=[A4, B4, A3, letter, legal]) ) + + (TIFF-M-base) :- + (& (image-file-structure=TIFF-M) + (MRC-mode>=1) + (MRC-max-stripe-size<=256) ) + + (TIFF-M-full) :- + (& (image-file-structure=TIFF-M) + (MRC-mode>=1) ) + + + + + + + + + +Klyne & McIntyre Standards Track [Page 55] + +RFC 2879 Content Feature Schema for Internet Fax (V2) August 2000 + + + Support for multiple TIFF profiles may be indicated by combining + their expressions with the OR operator; e.g. + + (| (TIFF-F) (TIFF-S) (TIFF-J) ) + + indicates support for all black-and-white modes. + + TIFF-M is a composite mode and must be used in conjunction with + some other mode to define the particular capabilities of a + receiver; e.g. + + (| (TIFF-M-base) + (TIFF-S) (TIFF-J-full) (TIFF-C-base) (TIFF-L-full) ) + + Each sub-image in an MRC image must conform to the capabilities + indicated AND also to any additional constraints imposed by the MRC + structure, such as bi-level mask layer, etc. See sections A.13 and + section 3.7. + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +Klyne & McIntyre Standards Track [Page 56] + +RFC 2879 Content Feature Schema for Internet Fax (V2) August 2000 + + +Appendix C: Changes from RFC 2531 + + 00a 23-Jun-1999 Updated Appendix B with more complete TIFF-FX + profile descriptions. Added note to section 3.5 + clarifying the meaning of (color=limited) in the + context of Internet fax. Added note to section + 3.6 and A.6 to clarify interpretation of color + depth. In A.6, noted that color gamut is not the + same as color resolution; fixed example. Split + section 3.7 into two sections, dealing with simple + image coding options and MRC composite image + options. Added new feature tag 'color-illuminant' + (sections 3.6, A.5). Added cross-references from + TIFF-M image file structure to MRC-mode tag. + Updated introduction and references. + + 00b 10-Aug-1999 Bring examples into line with T.30 mapping + document [4], and reorganize to make the + expression structure less complex. Add details of + mailing list for discussion. Added JPEG-only + colour example. Change definition of image-file- + structure tag to indicate more precisely what is + being defined, and to draw out the distinction + between a file structure to contain MRC images + (image-file-structure), and the MRC image model + (MRC-mode). + + 01a 01-Oct-1999 Update author's address and some references. + + 01b 05-Jan-2000 Incorporate last-call review comments (all + editorial). + + + + + + + + + + + + + + + + + + + + +Klyne & McIntyre Standards Track [Page 57] + +RFC 2879 Content Feature Schema for Internet Fax (V2) August 2000 + + +Full Copyright Statement + + Copyright (C) The Internet Society (2000). All Rights Reserved. + + This document and translations of it may be copied and furnished to + others, and derivative works that comment on or otherwise explain it + or assist in its implementation may be prepared, copied, published + and distributed, in whole or in part, without restriction of any + kind, provided that the above copyright notice and this paragraph are + included on all such copies and derivative works. However, this + document itself may not be modified in any way, such as by removing + the copyright notice or references to the Internet Society or other + Internet organizations, except as needed for the purpose of + developing Internet standards in which case the procedures for + copyrights defined in the Internet Standards process must be + followed, or as required to translate it into languages other than + English. + + The limited permissions granted above are perpetual and will not be + revoked by the Internet Society or its successors or assigns. + + This document and the information contained herein is provided on an + "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING + TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING + BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION + HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF + MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. + +Acknowledgement + + Funding for the RFC Editor function is currently provided by the + Internet Society. + + + + + + + + + + + + + + + + + + + +Klyne & McIntyre Standards Track [Page 58] + |