Fax working group Lloyd McIntyre INTERNET-DRAFT Xerox Corporation Category: Work-in-progress Graham Klyne 5GM/Content Technology Ltd September 1998 Expires: March 1999 Internet fax T.30 Feature Mapping Status of this memo This document is an Internet-Draft. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet-Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as ``work in progress''. To view the entire list of current Internet-Drafts, please check the "1id-abstracts.txt" listing contained in the Internet-Drafts Shadow Directories on ftp.is.co.za (Africa), ftp.nordu.net (Northern Europe), ftp.nis.garr.it (Southern Europe), munnari.oz.au (Pacific Rim), ftp.ietf.org (US East Coast), or ftp.isi.edu (US West Coast). [[INTENDED STATUS: This memo provides information for the Internet community. It does not specify an Internet standard of any kind. Distribution of this memo is unlimited.]] Copyright Notice Copyright (C) The Internet Society 1998. All Rights Reserved. Abstract This document describes how to map Group 3 fax capability identification bits, described in ITU-T.30 [6], into the Internet fax feature schema described in "Content feature schema for Internet fax" [4]. This is a companion to the fax feature schema document [4], which itself defines a profile of the media feature registration mechanisms [1,2,3], for use in performing capability identification between extended Internet fax systems [5]. McIntyre/Klyne Work-in-progress [Page 1] RFC nnnn Internet fax T.30 Feature Mapping September 1998 Table of contents 1. Introduction ............................................3 1.1 Organization of this document 3 1.2 Terminology and document conventions 3 1.3 Revision history 4 1.4 Unfinished business 4 2. Combining feature tags ..................................4 2.1 Relationship to Group 3 fax 4 2.2 Feature set descriptions 5 2.3 Examples 5 2.3.1 Data resource example 5 2.3.2 Recipient capabilities example 6 3. Survey of media-related T.30 capability bits ............6 3.1 DIS/DTC bit 15 (resolution) 6 3.2 DIS/DTC bit 16 (MR coding) 6 3.3 DIS/DTC bits 17,18 (width) 7 3.4 DIS/DTC bits 19,20 (length) 7 3.5 DIS/DTC bit 31 (MMR coding) 7 3.6 DIS/DTC bit 36 (JBIG multi-level coding) 7 3.7 DIS/DTC bit 37 (plane interleave) 7 3.8 DIS/DTC bits 41,42,43 (resolution) 8 3.9 DIS/DTC bits 44,45 (preferred units) 8 3.10 DIS/DTC bit 68 (JPEG) 9 3.11 DIS/DTC bit 69 (colour) 9 3.12 DIS/DTC bit 71 (bits/pixel) 9 3.13 DIS/DTC bit 73 (no subsampling) 9 3.14 DIS/DTC bit 74 (custom illuminant) 9 3.15 DIS/DTC bit 75 (custom gamut) 10 3.16 DIS/DTC bits 76,77 (paper size) 10 3.17 DIS/DTC bits 78,79 (JBIG bi-level coding) 10 3.18 DIS/DTC bit 92,93,94 (MRC level) 10 3.19 DIS/DTC bit 95 (MRC strip size) 11 3.20 DIS/DTC bit 97 (resolution) 11 3.21 DIS/DTC bit 98 (resolution) 11 4. Summary of T.30 capability dependencies .................11 4.1 Image coding 11 4.1.1 Bi-level coding 12 4.1.2 Multi-level coding 12 4.1.3 MRC coding 13 4.2 Resolution and units 13 4.3 Colour capabilities 15 4.4 Document size 15 5. Mapping T.30 capabilities to fax feature schema .........16 6. Example .................................................16 7. Security considerations .................................16 8. Full copyright statement ................................16 9. Acknowledgements ........................................17 10. References .............................................17 11. Authors' addresses .....................................18 McIntyre/Klyne Work-in-progress [Page 2] RFC nnnn Internet fax T.30 Feature Mapping September 1998 1. Introduction This document describes how to map Group 3 fax capability identification bits, described in ITU-T.30 [6], into the Internet fax feature schema described in "Content feature schema for Internet fax" [4]. This is a companion to the fax feature schema document [4], which itself defines a profile of the media feature registration mechanisms [1,2,3], for use in performing capability identification between extended Internet fax systems [5]. 1.1 Organization of this document Section 2 introduces the mechanisms that combine feature tag constraints to describe complex recipient capabilities. Section 3 surveys Group 3 fax (T.30) capability bits that relate to media handling capabilities, and indicates corresponding feature tags used to describe equivalent capabilities of an eifax system. Setion 4 describes the dependencies between Group 3 fax (T.30) capability bits. These are presented in a decision table format [16] with descriptive text in place of the action bodies. Section 5 describes a formal mechanism for converting Group 3 fax (T.30) capability masks to fax feature schema statements. The conversion process is driven by the decision tables introduced previously, using fax feature feature schema statements and combining rules in the action bodies. Section 6 presents a fairly complex example of a Group 3 fax (T.30) capability mask, and uses the formal mechanism described previously to convert that into a corresponding fax feature schema statement. 1.2 Terminology and document conventions eifax system is used to describe any software, device or combination of these that conforms to the specification "Extended Facsimile Using Internet Mail" [5]. Feature is used as defined in [15]. (See also section 2 of this memo.) Feature tag is used as defined in [15]. (See also section 2.) Feature collection is used as defined in [2]. (See also section 2.) McIntyre/Klyne Work-in-progress [Page 3] RFC nnnn Internet fax T.30 Feature Mapping September 1998 Feature set is used as defined in [2]. (See also section 2.) 1.3 Revision history 00a 29-Sep-1998 Initial draft. 1.4 Unfinished business . Section 5: T.30 to fax schema conversion . Section 6: example . Update references when available: Complete G3fax references 2. Combining feature tags A fax document can be described by media features. Any single media feature value can be thought of as just one component of a feature collection that describes some instance of a document (e.g. a printed fax, a displayed image, etc.). Such a feature collection consists of a number of media feature tags (each per [1]) and associated feature values. A feature set contains a number of feature collections. Thus, a feature set can describe a number of different fax document instances. These can correspond to different treatments of a single document (e.g. different resolutions used for printing a given fax), a number of different documents subjected to a common treatment (e.g. the range of different images that can be rendered on a given display), or some combination of these (see examples below). Thus, a description of a feature set can describe the rendering requirements of a fax document or the capabilities of a receiving eifax system. 2.1 Relationship to Group 3 fax A "feature tag" can be compared with a single bit in a T.30 DCS frame, describing a specific attribute of a specific fax document. A "feature collection" corresponds to a complete T.30 DCS frame, describing a range of attributes of a specific fax document. A "feature set" corresponds to a DIS or DTC frame, describing the range of document attributes that can be accepted by a given fax machine. McIntyre/Klyne Work-in-progress [Page 4] RFC nnnn Internet fax T.30 Feature Mapping September 1998 Within T.30 DIS/DTC frames, dependencies between the various capabilities are implicit in the definitions of the capabilities. E.g. multi-level coding (DIS/DTC bit 68) requires support for 200*200dpi resolution (DIS/DTC bit 15). In the feature set description framework used by eifax systems [1,2,3,4] such dependencies between different features are expressed explicitly. Later sections of this memo describe how the implicit dependencies of T.30 are expressed using the media feature set notation. 2.2 Feature set descriptions The general approach to describing feature sets, described more fully in [2], is use functions ("predicates") that, when applied to a feature collection value, yield a Boolean value that is TRUE if the feature collection describes an acceptable fax document instance, otherwise FALSE. P(F) P(F) = TRUE <- : -> P(F) = FALSE : +----------:----------+ This box represents some | : | universe of fax documents (F) | Included : Excluded | from which some acceptable subset | : | is selected by the predicate P. +----------:----------+ : 2.3 Examples In the examples below the following notation is used: (x ? y) tests feature tag 'x' for some relationship with value 'y'. (| p1 p2 ... pn ) represents the logical-OR of predicates 'p1', 'p2' up to 'pn'. (& p1 p2 ... pn ) represents the logical-AND of predicates 'p1', 'p2' up to 'pn'. 2.3.1 Data resource example The following expression uses the syntax of [x] to describe a data resource that can be displayed either: (a) as a 750x500 pixel image using 15 colours, or (b) at 150dpi on an A4 page. (| (& (pix-x=750) (pix-y=500) (color=15) ) (& (dpi>=150) (papersize=iso-A4) ) ) McIntyre/Klyne Work-in-progress [Page 5] RFC nnnn Internet fax T.30 Feature Mapping September 1998 2.3.2 Recipient capabilities example The following expression describes a receiving system that has: (a) a screen capable of displaying 640*480 pixels and 16 million colours (24 bits per pixel), 800*600 pixels and 64 thousand colours (16 bits per pixel) or 1024*768 pixels and 256 colours (8 bits per pixel), or (b) a printer capable of rendering 300dpi on A4 paper. (| (& (| (& (pix-x<=640) (pix-y<=480) (color<=16777216) ) (& (pix-x<=800) (pix-y<=600) (color<=65535) ) (& (pix-x<=1024) (pix-y<=768) (color<=256) ) ) (media=screen) ) (& (dpi=300) (media=stationery) (papersize=iso-A4) ) ) 3. Survey of media-related T.30 capability bits The following sections refer to T.30 DIS/DTC bits identified and described in Table 2/T.30 and accompanying notes. Bit numbers that are not referenced below are considered to be not related to media features, hence not relevant to the Internet fax feature schema. NOTE: some of the DIS/DTC bits identified below are documented in revisions of the T.30 specification that are not yet publicly available from the ITU. 3.1 DIS/DTC bit 15 (resolution) All Group 3 fax systems are required to support a basic resolution of 200*100dpi (dots per inch) or 8*3.85dpmm (dots per millimetre). Setting this bit indicates additional support for 200*200dpi or 8*7.7dpmm. See also: bits 44,45. 3.2 DIS/DTC bit 16 (MR coding) All Group 3 fax systems are required to support Modified Huffman (MH) 1-dimensional coding for bi-level images. (A bi-level image is one with just two pixel states such as black and white, as opposed to a grey-scale or colour image.) Setting this bit indicates additional support for Modified Read (MR) 2-dimensional coding for bi-level images. Both MH and MR coding are described in ITU T.4 [7]. See also: bits 31,78,79. McIntyre/Klyne Work-in-progress [Page 6] RFC nnnn Internet fax T.30 Feature Mapping September 1998 3.3 DIS/DTC bits 17,18 (width) All Group 3 fax systems are required to support 215mm paper width. These bits can be set to indicate additional support for 255mm and 303mm paper widths. See also: bits 76,77. 3.4 DIS/DTC bits 19,20 (length) All Group 3 fax systems are required to support 297mm paper length. These bits can be set to indicate additional support for 364mm and unlimited paper lengths. See also: bits 76,77. 3.5 DIS/DTC bit 31 (MMR coding) Setting this bit indicates support for Modified Read (MR) 2- dimensional coding for bi-level images, in addition to the required support for MH coding. MMR coding is described in ITU T.6 [8]. See also: bits 6,78,79. 3.6 DIS/DTC bit 36 (JBIG multi-level coding) Setting this bit indicates support for JBIG lossless coding for multi-level images. JBIG coding for multi-level images is described in ITU T.43 [10]. See also: bits 68,69. 3.7 DIS/DTC bit 37 (plane interleave) Setting this bit indicates support for plane interleave for JBIG- coded multi-level images, in addition to stripe interleave coding. JBIG coding for multi-level images is described in ITU T.43 [10]. [[[Is this reference appropriate?]]] See also: bit 36. McIntyre/Klyne Work-in-progress [Page 7] RFC nnnn Internet fax T.30 Feature Mapping September 1998 3.8 DIS/DTC bits 41,42,43 (resolution) Setting these bits indicates support for resolutions in addition to 100*200dpi and 200*200dpi, or 8*3.85dpmm and 8*7.7dpmm. Bit 41 indicates support for 8*15.4dpmm bi-level images (independently of the settings of bits 44 and 45). Bit 42 indicates support for 300*300dpi bi-level images (independently of the settings of bits 44 and 45). [[[Also applies to multi-level images or MRC mask if bit 97 is set???]]] Bit 43 indicates support for 400*400dpi and/or 16*15.4dpmm bi-level images, depending uppon the settings of bits 44 and 45. [[[Also applies to multi-level images or MRC mask if bit 97 is set???]]] See also: bits 44,45,97. 3.9 DIS/DTC bits 44,45 (preferred units) These bits are used to indicate the preferred resolution units for received images. Because the exact resolution and x/y pixel density measures in dpi or dpmm are slightly different, some image size and aspect ratio distortion may occur if the sender and receiver use different units. Even when sender and recipient have different preferred units, image transfer must be accomplished. For most fax uses, the dpi and dpmm measurements are sufficiently close to each other that the difference is not noticed. The preferred units setting affects the interpretation of the following resolutions: dpi dpmm --- ---- Base 200*100 8*3.85 Bit 15 200*200 8*7.7 Bit 43 400*400 16*15.4 See also: bits 15, 43 McIntyre/Klyne Work-in-progress [Page 8] RFC nnnn Internet fax T.30 Feature Mapping September 1998 3.10 DIS/DTC bit 68 (JPEG) This bit indicates support for JPEG coding of multi-level images. JPEG coding for multi-level images is described in ITU T.81 [12]. See also: bits 15,36,69,73 3.11 DIS/DTC bit 69 (colour) This bit indicates support for multi-level colour images, as opposed to just grey-scale. See also: bits 36,68,73. 3.12 DIS/DTC bit 71 (bits/pixel) Standard support for multi-level images uses 8 bits per pixel. Setting this bit indicates additional support for 12 bits per pixel. See also: bit 68. 3.13 DIS/DTC bit 73 (no subsampling) Standard support for multi-level images uses 4:1:1 chrominance subsampling. That is, for each 4 luminance samples in the image description there is a single chrominance sample. Setting this bit indicates that colour images without subsampling can also be supported. See also: bits 36,68,69. 3.14 DIS/DTC bit 74 (custom illuminant) Setting this bit indicates that a custom illuminant can be supported for multi-level images. [[[Including grey-scale?]]] Use of a custom illuminant with multi-level images is described in ITU T.42 [9]. See also: bit 68. McIntyre/Klyne Work-in-progress [Page 9] RFC nnnn Internet fax T.30 Feature Mapping September 1998 3.15 DIS/DTC bit 75 (custom gamut) Setting this bit indicates that a custom gamut can be supported for multi-level images. [[[Including grey-scale?]]] Use of a custom gamut with multi-level images is described in ITU T.42 [9]. See also: bit 68. 3.16 DIS/DTC bits 76,77 (paper size) All Group 3 faxes are required to support A4 paper size. These bits can be set to indicate additional support for North American letter and legal paper sizes. See also: bits 17,18,19,20. 3.17 DIS/DTC bits 78,79 (JBIG bi-level coding) Setting bit 78 indicates support for JBIG coding of bi-level images, in addition to the required support for MH coding. Setting bits 78 and 79 indicates additional support for using optional 'LO' with JBIG coded bi-level images. Basic bi-level JBIG coding uses 128 lines per stripe; the 'LO' option allows other values to be used. JBIG coding of bi-level images is described in ITU-T.85 [14]. See also: bits 16,31. 3.18 DIS/DTC bit 92,93,94 (MRC level) If these bits are all zero, then Mixed Raster Content (MRC) coding is not supported. Otherwise, they represent a number in the range 1-7 that indicates an MRC capability level. MRC coding of images is described in ITU-T.44 [11]. See also: bit 95. McIntyre/Klyne Work-in-progress [Page 10] RFC nnnn Internet fax T.30 Feature Mapping September 1998 3.19 DIS/DTC bit 95 (MRC strip size) If bits 92-94 inducate an MRC coding capability, then this bit indicates the maximum strip size. If zero, the maximum strip size is 256 lines, otherwise the maximum strip size is a full page. MRC coding of images is described in ITU-T.44 [11]. See also: bits 92,93,94. 3.20 DIS/DTC bit 97 (resolution) Setting this bit indicates that the additional resolutions indicated by bits 42 and 43 may be used for multi-level images and any MRC mask layer. See also: bits 42,43,68. 3.21 DIS/DTC bit 98 (resolution) Setting this bit indicates that the additional resolution 100*100dpi may be used for multi-level images and any MRC mask layer. See also: bit 68. 4. Summary of T.30 capability dependencies This section contains a number of decision tables that indicate the allowable combinations of T.30 DIS/DTC mask bits. Within the decision table bodies, the following symbols are use to indicate values of T.30 DIS/DTC bits: 0 = bit set to '0' 1 = bit set to '1' x = don't care bit value: may be '0' or '1' *0 = bit must be '0' ('1' is invalid in given combination) *1 = bit must be '1' ('0' is invalid in given combination) # = bits in row combined to form a numeric value 4.1 Image coding MH coding is required as a minimum for Group 3 fax operation. McIntyre/Klyne Work-in-progress [Page 11] RFC nnnn Internet fax T.30 Feature Mapping September 1998 4.1.1 Bi-level coding <------- T.30 bits ---------> 15|16|31|36|37|68|69|73|78|79||Description --+--+--+--+--+--+--+--+--+--++--------------------------------------- x| 0| 0| | | | | | 0| 0||Compression = [MH] x| 1| 0| | | | | | 0| 0||Compression = [MH,MR] x| 0| 1| | | | | | 0| 0||Compression = [MH,MMR] x| 1| 1| | | | | | 0| 0||Compression = [MH,MR,MMR] x| 0| 0| | | | | | 1| 0||Compression = [MH,T.85] x| 1| 0| | | | | | 1| 0||Compression = [MH,MR,T.85] x| 0| 1| | | | | | 1| 0||Compression = [MH,MMR,T.85] x| 1| 1| | | | | | 1| 0||Compression = [MH,MR,MMR,T.85] x| 0| 0| | | | | |*1| 1||Compression = [MH,T.85,T.85LO] x| 1| 0| | | | | |*1| 1||Compression = [MH,MR,T.85,T.85LO] x| 0| 1| | | | | |*1| 1||Compression = [MH,MMR,T.85,T.85LO] x| 1| 1| | | | | |*1| 1||Compression = [MH,MR,MMR,T.85,T.85LO] | | | | | | | | | ||MH = 1-D per T.4 | | | | | | | | | ||MR = 2-D per T.4 | | | | | | | | | ||MMR = 2-D per T.6 | | | | | | | | | ||T.85 = Basic JBIG per T.85 | | | | | | | | | ||T.85LO = Optional LO with T.85/JBIG --+--+--+--+--+--+--+--+--+--++--------------------------------------- 4.1.2 Multi-level coding Note: When 37, 69, 73, 79 and 95 are set to "1", the feature represented by "0" is also available. Example: If plane interleave is available then stripe interleave is also available. <------- T.30 bits ---------> 15|16|31|36|37|68|69|73|78|79||Description --+--+--+--+--+--+--+--+--+--++--------------------------------------- x| | |*0| x| 0| x| x| | ||No grey or colour (no T.43 or JPEG) *1| | | 0| x| 1| 0| x| | ||JPEG, grey scale only *1| | | 0| x| 1| 1| 0| | ||JPEG, full colour, subsampling *1| | | 0| x| 1| 1| 1| | ||JPEG, full colour, no subsampling *1| | | 1| 0| 1| 0| x| | ||T.43, JPEG, grey only, stripe i/l *1| | | 1| 1| 1| 0| x| | ||T.43, JPEG, grey only, plane i/l *1| | | 1| 0| 1| 1| 0| | ||T.43, JPEG, colour, stripe i/l, s/s *1| | | 1| 0| 1| 1| 1| | ||T.43, JPEG, colour, stripe i/l, no s/s *1| | | 1| 1| 1| 1| 0| | ||T.43, JPEG, colour, plane i/l, s/s *1| | | 1| 1| 1| 1| 1| | ||T.43, JPEG, colour, plane i/l, no s/s | | | | | | | | | ||'s/s' is 4:1:1 L*:a*:b* subsampling | | | | | | | | | ||'No s/s' is 1:1:1 L*:a*:b* subsampling | | | | | | | | | ||'stripe i/l' is stripe interleave | | | | | | | | | ||'plane i/l' is full-plane interleave --+--+--+--+--+--+--+--+--+--++--------------------------------------- McIntyre/Klyne Work-in-progress [Page 12] RFC nnnn Internet fax T.30 Feature Mapping September 1998 4.1.3 MRC coding Multi-level coders, as indicated above, are used within an MRC- coded image. <---- T.30 bits ------> 15|92|93|94|95| | | ||Description --+--+--+--+--+--+--+--++--------------------------------------- x| 0| 0| 0| x| | | ||MRC not accepted *1| #| #| #| 0| | | ||MRC level, max strip 256 lines *1| #| #| #| 1| | | ||MRC level, max strip full page | | | | | | | ||### is MRC performance level (1-7, per T.44) --+--+--+--+--+--+--+--++--------------------------------------- 4.2 Resolution and units Support for bi-level coding at least one of 200*100dpi or 8*3.85dpmm is required in all cases for Group 3 fax conformance. For multi-level coders (colour/grey) the base resolution is 200*200dpi (i.e. bit 15 must be set). When multi-level coders (JPEG or T.43) are used, only inch-based square resolutions are available. However, the base non-square resolution (i.e. 200x100dpi or 8x3.85dpmm) must still be available as a capability for use with the mandatory bi-level coder (MH). Hence, any references to metric and non-square resolutions in the table below apply only to bi-level coders. In the following table: dpi = dots per inch dpmm = dots per millimetre McIntyre/Klyne Work-in-progress [Page 13] RFC nnnn Internet fax T.30 Feature Mapping September 1998 <------- T.30 bits ------> 15|41|42|43|44|45|68|97|98||Description --+--+--+--+--+--+--+--+--++----------------------------------------- 0| | | 0| x| x| | | ||Resolution = base only | | | | | | | | || 1| | | 0| 0| 0| | | ||Invalid 1| | | 0| 0| 1| | | ||Resolution = 8*3.85dpmm or 8*7.7dpmm 1| | | 0| 1| 0| | | ||Resolution = 200*100dpi or 200*200dpi 1| | | 0| 1| 1| | | ||Resolution = 8*3.85dpmm or 8*7.7dpmm | | | | | | | | || or 200*100dpi or 200*200dpi | | | | | | | | || 0| | | 1| 0| 0| | | ||Invalid 0| | | 1| 0| 1| | | ||Resolution = 8*3.85dpmm or 16*15.4dpmm 0| | | 1| 1| 0| | | ||Resolution = 200*100dpi or 400*400dpi 0| | | 1| 1| 1| | | ||Resolution = 8*3.85dpmm or 16*15.4dpmm | | | | | | | | || or 200*100dpi or 400*400dpi | | | | | | | | || 1| | | 1| 0| 0| | | ||Invalid 1| | | 1| 0| 1| | | ||Resolution = 8*3.85dpmm or 8*7.7dpmm | | | | | | | | || or 16*15.4dpmm 1| | | 1| 1| 0| | | ||Resolution = 200*100dpi or 200*200dpi | | | | | | | | || or 400*400dpi 1| | | 1| 1| 1| | | ||Resolution = 8*7.7dpmm or 8*7.7dpmm | | | | | | | | || or 16*15.4dpmm | | | | | | | | || or 200*100dpi or 200*200dpi | | | | | | | | || or 400*400dpi --+--+--+--+--+--+--+--+--++----------------------------------------- | 0| | | | | | | ||Resolutions as above | 1| | | x| x| | | ||Also supports 8*15.4dpmm (bi-level only) | | | | | | | | ||Independent of bits 44,45 --+--+--+--+--+--+--+--+--++----------------------------------------- | | 0| | | | | | ||Resolutions as above | | 1| | x| x| | | ||Also supports 300*300dpi | | | | | | | | ||Independent of bits 44,45 --+--+--+--+--+--+--+--+--++----------------------------------------- | | | | | | x| 0| ||Resolutions as above | | | | | |*1| 1| ||Also 300*300dpi or 400*400dpi (see below) | | | | | | | | ||(Applies colour, grey-scale or MRC mask) | | | | | | | | ||(Valid only when bit 42 or 43 is set.) | | | | | | | | ||(42 => 300dpi, 43=>400dpi) --+--+--+--+--+--+--+--+--++----------------------------------------- | | | | | | x| | 0||Resolutions as above | | | | x| x|*1| | 1||Also 100*100dpi | | | | | | | | ||(Applies colour, grey-scale or MRC only) | | | | | | | | ||Independent of bits 44,45 --+--+--+--+--+--+--+--+--++----------------------------------------- McIntyre/Klyne Work-in-progress [Page 14] RFC nnnn Internet fax T.30 Feature Mapping September 1998 4.3 Colour capabilities Bit 68 (JPEG) is required for any colour/grey scale mode, and bit 36 indicates additional T.43 capability. <------- T.30 bits ---> 36|68|69|71|74|75| | ||Description --+--+--+--+--+--+--+--++----------------------------------------- 0| 0| x| x| x| x| | ||No grey scale or colour x| 1| 0| | | | | ||Grey scale only 0| 1| 1| | | | | ||Full colour capability (CIE L*a*b*) 1| 1| 1| | | | | ||Full colour capability: | | | | | | | || (CIE L*a*b*, palette, RGB 1 bit/colour | | | | | | | || and CMY(K)1 bit/colour) --+--+--+--+--+--+--+--++----------------------------------------- x| 1| | 0| | | | ||8 bits/pixel x| 1| | 1| | | | ||8 or 12 bits/pixel --+--+--+--+--+--+--+--++----------------------------------------- x| 1| | | 0| | | ||CIE standard illuminant D50 (per T.42) x| 1| | | 1| | | ||Custom illuminants (definition provided) --+--+--+--+--+--+--+--++----------------------------------------- x| 1| | | | 0| | ||Default gamut (per T.42) x| 1| | | | 1| | ||Custom gamuts (definition provided) --+--+--+--+--+--+--+--++----------------------------------------- 4.4 Document size A4 width (215mm) is required as a minimum for Group 3 fax conformance. A Group 3 fax machine must always be able to receive an A4 image. <---- T.30 bits ------> 17|18|19|20|76|77| | ||Description (later to be media features) --+--+--+--+--+--+--+--++----------------------------------------- 0| 0| | | | | | ||Width = 215mm 1| 0| | | | | | ||Width = 215mm or 255mm 0| 1| | | | | | ||Width = 215mm, 255mm or 303mm 1| 1| | | | | | ||Invalid - interpret as (17=0,18=1) | | | | | | | ||(measurements described as scan line length) | | | | | | | ||(corresp. inch measurements: T.4 sect 2.2) --+--+--+--+--+--+--+--++----------------------------------------- | | 0| 0| | | | ||Length = 297mm (A4) | | 1| 0| | | | ||Length = 297mm (A4) or 364mm (B4) | | 0| 1| | | | ||Length = unlimited | | 1| 1| | | | ||Invalid --+--+--+--+--+--+--+--++----------------------------------------- | | | | 0| 0| | ||Papersize = A4 | | | | 1| 0| | ||Papersize = A4 or NA-Letter | | | | 0| 1| | ||Papersize = A4 or NA-Legal | | | | 1| 1| | ||Papersize = A4 or NA-Letter or NA-Legal --+--+--+--+--+--+--+--++----------------------------------------- McIntyre/Klyne Work-in-progress [Page 15] RFC nnnn Internet fax T.30 Feature Mapping September 1998 5. Mapping T.30 capabilities to fax feature schema [[[This would be a more formal treatment of the material in section 4, describing how to map various combinations of T.30 bits into the fax feature schema using a number of decision tables containing fax feature schema statements, and some formal combining rules using the conneg -algebra- format.]]] 6. Example [[[I am proposing a single example that starts with a fairly complex T.30 capability mask, and maps that into the corresponding fax-schema feature set expression]]] 7. Security considerations Security considerations are discussed in the fax feature schema description [4]. This memo is not believed to introduce any additional security concerns. 8. Full copyright statement Copyright (C) The Internet Society 1998. 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. McIntyre/Klyne Work-in-progress [Page 16] RFC nnnn Internet fax T.30 Feature Mapping September 1998 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. 9. Acknowledgements The authors gratefully ackowledge the following persons who made comments on earlier versions of this memo: Mr. Hiroshi Tamura, [[...]]. 10. References [1] "Media Feature Tag Registration Procedure" Koen Holtman, TUE Andrew Mutz, Hewlett-Packard Ted Hardie, NASA Internet draft: Work in progress, July 1998. [2] "A syntax for describing media feature sets" Graham Klyne, 5GM/Content Technologies Internet draft: " Work in progress, September 1998. [3] "Media Features for Display, Print, and Fax" Larry Masinter, Xerox PARC Koen Holtman, TUE Andrew Mutz, Hewlett-Packard Dan Wing, Cisco Systems Internet draft: Work in progress, September 1998. [4] "Content feature schema for Internet fax" Lloyd McIntyre, Xerox Corporation Graham Klyne, 5GM/Content Technologies Internet draft: Work in progress, August 1998. [5] "Extended Facsimile Using Internet Mail Larry Masinter, Xerox Corporation Dan Wing, Cisco Systems Internet draft: Work in progress, September 1998. McIntyre/Klyne Work-in-progress [Page 17] RFC nnnn Internet fax T.30 Feature Mapping September 1998 [6] "Procedures for document facsimile transmission in the general switched telephone network" ITU-T Recommendation T.30 International Telecommunications Union July 1996 [7] T.4 (basic fax coding formats: MH, MR) [8] T.6 (extended 2-D fax coding format: MMR) [9] T.42 (custom illuminant, gamut) [10] T.43 (JBIG for colour/grey) [11] T.44 (MRC) [12] T.81 (JPEG) [13] T.82 (JBIG?????????) [14] T.85 (bi-level JBIG) [15] "Requirements for protocol-independent content negotiation" G. Klyne, Integralis Ltd. Internet draft: Work in progress, March 1998. [16] "Programs from Decision Tables" E. Humbey Macdonald/American Elsevier computer monographs (19), 1973 ISBN 0-444-19569-6/0-356-04126-3 (This is an old title, and may not be still in print. It contains a number of references to decision table articles published in Communications of the ACM: August 1967, September 1970, January 1966, November 1966, October 1968, January 1965, February 1964, June 1970, November 1965, June 1965, February 1971.) 11. Authors' addresses Lloyd McIntyre Xerox Corporation Mailstop PAHV-305 3400 Hillview Ave. Palo Alto, CA 94304 USA Telephone: +1-650-813-6762 Facsimile: +1-650-845-2340 E-mail: Lloyd.McIntyre@pahv.xerox.com McIntyre/Klyne Work-in-progress [Page 18] RFC nnnn Internet fax T.30 Feature Mapping September 1998 Graham Klyne 5th Generation Messaging Ltd. Content Technologies Ltd. 5 Watlington Street Forum 1, Station Road Nettlebed Theale Henley-on-Thames, RG9 5AB Reading, RG7 4RA United Kingdom United Kingdom. Telephone: +44 1491 641 641 +44 118 930 1300 Facsimile: +44 1491 641 611 +44 118 930 1301 E-mail: GK@ACM.ORG McIntyre/Klyne Work-in-progress [Page 19]