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diff --git a/doc/rfc/rfc2880.txt b/doc/rfc/rfc2880.txt new file mode 100644 index 0000000..cb019ed --- /dev/null +++ b/doc/rfc/rfc2880.txt @@ -0,0 +1,2075 @@ + + + + + + +Network Working Group L. McIntyre +Request for Comments: 2880 Xerox Corporation +Category: Informational G. Klyne + Content Technologies + August 2000 + + + Internet Fax T.30 Feature Mapping + +Status of this Memo + + 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 (2000). 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]. + +Table of Contents + + 1. Introduction .............................................3 + 1.1 Organization of this document ........................3 + 1.2 Terminology and document conventions .................3 + 1.3 Discussion of this document ..........................4 + 2. Combining feature tags ...................................4 + 2.1 Relationship to Group 3 fax ..........................5 + 2.2 Feature set descriptions .............................5 + 2.3 Examples .............................................5 + 2.3.1 Data resource example ............................6 + 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) ...........................7 + 3.3 DIS/DTC bits 17,18 (width) ...........................7 + 3.4 DIS/DTC bits 19,20 (length) ..........................7 + + + +McIntyre & Klyne Informational [Page 1] + +RFC 2880 Internet Fax T.30 Feature Mapping August 2000 + + + 3.5 DIS/DTC bit 31 (MMR coding) ..........................7 + 3.6 DIS/DTC bit 36 (JBIG multi-level coding) .............8 + 3.7 DIS/DTC bit 37 (plane interleave) ....................8 + 3.8 DIS/DTC bits 41,42,43 (resolution) ...................8 + 3.9 DIS/DTC bits 44,45 (preferred units) .................9 + 3.10 DIS/DTC bit 68 (JPEG) ...............................9 + 3.11 DIS/DTC bit 69 (colour) .............................9 + 3.12 DIS/DTC bit 71 (bits/sample) .......................10 + 3.13 DIS/DTC bit 73 (no subsampling) ....................10 + 3.14 DIS/DTC bit 74 (custom illuminant) .................10 + 3.15 DIS/DTC bit 75 (custom gamut) ......................10 + 3.16 DIS/DTC bits 76,77 (paper size) ....................11 + 3.17 DIS/DTC bit 78 (JBIG bi-level coding) ..............11 + 3.18 DIS/DTC bit 79 (JBIG stripe size) ..................11 + 3.19 DIS/DTC bit 92,93,94 (MRC maximum functional mode) .11 + 3.20 DIS/DTC bit 95 (MRC stripe size) ...................12 + 3.21 DIS/DTC bit 97 (resolution) ........................12 + 3.22 DIS/DTC bit 98 (resolution) ........................12 + 4. Summary of T.30 capability dependencies .................12 + 4.1 Image coding ........................................13 + 4.1.1 Bi-level coding .................................13 + 4.1.2 Multi-level coding ..............................14 + 4.1.3 MRC format ......................................14 + 4.2 Resolution and units ................................15 + 4.3 Colour capabilities .................................17 + 4.4 Document size .......................................18 + 5. Mapping T.30 capabilities to fax feature schema .........18 + 5.1 Image coding ........................................20 + 5.1.1 Bi-level coding .................................20 + 5.1.2 Multi-level coding ..............................21 + 5.1.3 MRC format ......................................23 + 5.2 Resolution and units ................................23 + 5.3 Colour capabilities .................................24 + 5.4 Document size .......................................26 + 6. Examples ................................................26 + 6.1 Common black-and-white fax machine ..................27 + 6.1.1 Corresponding Internet fax capabilities .........29 + 6.2 Full-featured color fax machine .....................30 + 7. Security Considerations .................................34 + 8. Acknowledgements ........................................34 + 9. References ..............................................34 + 10. Authors' Addresses .....................................36 + Full Copyright Statement ...................................37 + + + + + + + + +McIntyre & Klyne Informational [Page 2] + +RFC 2880 Internet Fax T.30 Feature Mapping August 2000 + + +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. + + Section 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 schema statements and combining rules + in the action bodies. + + Section 6 presents an 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.) + + + + + +McIntyre & Klyne Informational [Page 3] + +RFC 2880 Internet Fax T.30 Feature Mapping August 2000 + + + Feature collection + is used as defined in [2]. (See also section 2.) + + Feature set + is used as defined in [2]. (See also section 2.) + +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. 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. + + + + + + + + + +McIntyre & Klyne Informational [Page 4] + +RFC 2880 Internet Fax T.30 Feature Mapping August 2000 + + +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. + + 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 to 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'. + + + +McIntyre & Klyne Informational [Page 5] + +RFC 2880 Internet Fax T.30 Feature Mapping August 2000 + + + (& 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 [2] 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=A4) ) ) + +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=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 [6]. 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 + may be 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. + + + +McIntyre & Klyne Informational [Page 6] + +RFC 2880 Internet Fax T.30 Feature Mapping August 2000 + + + For multi-level images, 200*200dpi is the basic resolution, and this + bit must be set. The other basic resolution options apply to bi- + level images only. + + 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. + +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 Modified Read (MMR) + 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 16,78,79. + + + + + + +McIntyre & Klyne Informational [Page 7] + +RFC 2880 Internet Fax T.30 Feature Mapping August 2000 + + +3.6 DIS/DTC bit 36 (JBIG multi-level coding) + + If multi-level images are to be handled, support for JPEG coding is + required (i.e. bit 68 must be set). Setting bit 36 indicates + additional support for JBIG lossless coding of multi-level images. + + JBIG coding for multi-level images is described in ITU T.43 [10] and + T.4 Annex G [7]. + + 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, which is + standard for JBIG multi-level images. + + JBIG coding for multi-level images is described in ITU T.43 [10] and + T.4 Annex G [7]. + + See also: bit 36. + +3.8 DIS/DTC bits 41,42,43 (resolution) + + Setting these bits indicates support for resolutions in addition to + 200*100dpi and 200*200dpi, or 8*3.85dpmm and 8*7.7dpmm. (Or in + addition to the basic 200*200dpi resolution when using a multi-level + image mode.) + + 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 upon the settings of bits 44 and 45. Also applies + to multi-level images or MRC mask if bit 97 is set. + + See also: bits 15,44,45,97. + + + + + + + + + + +McIntyre & Klyne Informational [Page 8] + +RFC 2880 Internet Fax T.30 Feature Mapping August 2000 + + +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 detailed interpretation of + the following resolutions: + + dpi dpmm (dpi equivalent) + --- ---- + Base 200*100 8*3.85 204*98 + Bit 15 200*200 8*7.7 204*196 + Bit 43 400*400 16*15.4 408*391 + + But terminals are required to accept the inch- and metric-based + measures given above as equivalent, distorting the image if necessary + to accommodate the differences. + + See also: bits 15, 43 + +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] and + T.4 Annex E [7]. + + See also: bits 15,69,73 + +3.11 DIS/DTC bit 69 (colour) + + This bit indicates support for colour images, in addition to just + grey-scale. + + Both grey-scale and colour require multi-level coding. The + difference is that grey is single component while colour is multi- + component. + + See also: bits 36,68,73. + + + + +McIntyre & Klyne Informational [Page 9] + +RFC 2880 Internet Fax T.30 Feature Mapping August 2000 + + +3.12 DIS/DTC bit 71 (bits/sample) + + Standard support for multi-level images uses 8 bits per sample. + Setting this bit indicates additional support for 12 bits per sample. + + For a grey-scale multi-level image, there is just one sample per + pixel, giving 256 or 4096 possible pixel values. For a full colour + multi-level image there are three samples per pixel, giving 256^3 + (16777216) or 4096^3 (6871946736) possible values. + + When related to a mapped colour image, bit 71 also affects the + maximum number of entries in the mapping table: when it is reset, up + to 4096 different pixel values can be used; when set, up to 65536 + different values can be used. + + See also: bit 68. + +3.13 DIS/DTC bit 73 (no subsampling) + + Standard support for JPEG-coded multi-level images uses 4:1:1 + chrominance subsampling. That is, for each 4 luminance samples in + the image data there is a single chrominance sample. + + Setting this bit indicates that JPEG-coded colour images without + subsampling can also be supported. This is not applicable to JBIG + coding (bit 36). + + See also: bits 68,69. + +3.14 DIS/DTC bit 74 (custom illuminant) + + Standard support for multi-level images requires use of D50 + illuminant. Setting this bit indicates that a custom illuminant also + can be supported for multi-level images (both grey-scale and colour). + Details of the custom illuminant are contained in the image data. + + Use of a custom illuminant with multi-level images is described in + ITU T.4 Annex E [7]. + + See also: bits 36,68. + +3.15 DIS/DTC bit 75 (custom gamut) + + Standard support for a default colour gamut is required for multi- + level images. Setting this bit indicates that a custom gamut also + can be supported for multi-level images (both grey-scale and colour). + Details of the custom gamut are contained in the image data. + + + + +McIntyre & Klyne Informational [Page 10] + +RFC 2880 Internet Fax T.30 Feature Mapping August 2000 + + + The default gamut (L*=[0,100], a*=[-85, 85], b* = [-75, 125]), and + use of a custom gamut with multi-level images is described in ITU + T.42 [9] and T.4 Annex E [7]. + + See also: bits 36,68. + +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 bit 78 (JBIG bi-level coding) + + Setting bit 78 indicates support for JBIG coding of bi-level images + (using T.85 encoding rules), in addition to the required support for + MH coding. + + JBIG coding of bi-level images is described in ITU T.85 [14]. + + See also: bits 16,31,79. + +3.18 DIS/DTC bit 79 (JBIG stripe size) + + Setting bit 79 (along with bit 78) indicates support for the 'LO' + option with JBIG coded bi-level images. Basic bi-level JBIG coding + uses 128 lines per stripe; the 'LO' option allows other stripe sizes + to be used. + + The stripe size is used for all stripes except the last, which may + have fewer lines than the indicated value. + + JBIG coding of bi-level images is described in ITU T.85 [14]. + + See also: bits 16,31,78. + +3.19 DIS/DTC bit 92,93,94 (MRC maximum functional mode) + + 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 maximum functional mode. + + MRC coding of images is described in ITU T.44 [11] and T.4 Annex H + [17]. + + See also: bits 68,95. + + + +McIntyre & Klyne Informational [Page 11] + +RFC 2880 Internet Fax T.30 Feature Mapping August 2000 + + +3.20 DIS/DTC bit 95 (MRC stripe size) + + Standard support for MRC uses a maximum stripe size of 256 lines. + When this bit is set, the maximum stripe size is a full page. + + This bit is meaningful only if bits 92-94 indicate an MRC coding + capability. MRC coding of images is described in ITU T.44 [11] and + T.4 Annex H [17]. + + See also: bits 92,93,94. + +3.21 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. + + When this bit is set, bit 42 implies 300dpi and bit 43 implies 400dpi + for multi-level or MRC mask layer images (irrespective of the + preferred units indicated by bits 44 and 45). + + See also: bits 42,43,68. + +3.22 DIS/DTC bit 98 (resolution) + + Setting this bit indicates that the additional resolution 100*100dpi + may be used for multi-level images. + + NOTE: 100dpi is not used for bi-level images, including + the MRC mask layer. + + See also: bit 36,68,92-94. + +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 + + + + +McIntyre & Klyne Informational [Page 12] + +RFC 2880 Internet Fax T.30 Feature Mapping August 2000 + + +4.1 Image coding + + MH coding is required as a minimum for Group 3 fax operation. + +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 + | | | | | | | | | ||(Basic JBIG is 128 lines/stripe; LO + | | | | | | | | | || allows other stripe sizes to be used) +--+--+--+--+--+--+--+--+--+--++--------------------------------------- + + + + + + + + + + + + + + + + + + + + + + +McIntyre & Klyne Informational [Page 13] + +RFC 2880 Internet Fax T.30 Feature Mapping August 2000 + + +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 +--+--+--+--+--+--+--+--+--+--++--------------------------------------- + +4.1.3 MRC format + + Multi-level coders, as indicated above, are used for foreground and + background images within an MRC-format document. Bi-level codes + are used for the mask layer. + +<---- 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) +--+--+--+--+--+--+--+--++--------------------------------------- + + + + + + + + + + + + +McIntyre & Klyne Informational [Page 14] + +RFC 2880 Internet Fax T.30 Feature Mapping August 2000 + + +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) and MRC mask layers the base resolution is + 200*200dpi (i.e. bit 15 must be set). + + When multi-level coders (JPEG or T.43) or MRC 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. + + When describing MRC capabilities, 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. + + In the following table: + dpi = dots per inch + dpmm = dots per millimetre + + Preferred resolutions are indicated here, even though inch- or mm- + based units must be accepted, according to the T.30 protocol [6]. + + + + + + + + + + + + + + + + + + + + + + + + + +McIntyre & Klyne Informational [Page 15] + +RFC 2880 Internet Fax T.30 Feature Mapping August 2000 + + +<------- 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| | | | | | | ||Also supports 8*15.4dpmm (bi-level only) + | | | | | | | | ||Independent of bits 44,45 +--+--+--+--+--+--+--+--+--++----------------------------------------- + | | 0| | | | | | ||Resolutions as above + | | 1| | | | | | ||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 + | | | | | |*1| | 1||Also 100*100dpi + | | | | | | | | ||(Applies colour or grey-scale only) + | | | | | | | | ||(Independent of bits 44,45) +--+--+--+--+--+--+--+--+--++----------------------------------------- + + + + + +McIntyre & Klyne Informational [Page 16] + +RFC 2880 Internet Fax T.30 Feature Mapping August 2000 + + +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| | | | | ||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 and limited colour capability: + | | | | | | | || (CIE L*a*b*, palette, RGB 1 bit/colour + | | | | | | | || and CMY(K)1 bit/colour) +--+--+--+--+--+--+--+--++----------------------------------------- + | 0| | x| | | | || + | 1| | 0| | | | ||8 bits/pixel and up to 4096 palette entries + | 1| | 1| | | | ||8 or 12 bits/pixel, 65536 palette entries +--+--+--+--+--+--+--+--++----------------------------------------- + | 0| | | x| | | || + | 1| | | 0| | | ||CIE standard illuminant D50 (per T.42) + | 1| | | 1| | | ||Custom illuminants (definition provided) +--+--+--+--+--+--+--+--++----------------------------------------- + | 0| | | | x| | || + | 1| | | | 0| | ||Default gamut (per T.42) + | 1| | | | 1| | ||Custom gamuts (definition provided) +--+--+--+--+--+--+--+--++----------------------------------------- + + + + + + + + + + + + + + + + + + + + + + + + +McIntyre & Klyne Informational [Page 17] + +RFC 2880 Internet Fax T.30 Feature Mapping August 2000 + + +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 +--+--+--+--+--+--+--+--++----------------------------------------- + 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 + | | | | | | | ||(These in addition to paper sizes implied + | | | | | | | || by bits 17-20 above) +--+--+--+--+--+--+--+--++----------------------------------------- + +5. Mapping T.30 capabilities to fax feature schema + + This section follows the structure of the previous section, except + that the decision tables are restated with feature set expression + mappings in the action stub. The feature set expressions use media + feature tags presented in "Content feature schema for Internet fax" + [4]. + + To construct a feature set expression corresponding to a collection + of DIS frame bits: + + o Compare the DIS bits with each decision table in the following + sections (5.1 to 5.4). Some decision tables consist of a number + of sub-tables separated by horizontal lines. + + o The DIS bits will match exactly one row from each table or sub- + table: collect the corresponding feature set expression from the + action stub (the right hand column of the table). + + + +McIntyre & Klyne Informational [Page 18] + +RFC 2880 Internet Fax T.30 Feature Mapping August 2000 + + + o In the case of the table in section 5.2, which consists of + several sub-tables, combine the feature set expressions from each + sub-table with a logical-OR: (| s1 s2 ... sn ), where 's1', 's2' + etc. are the feature set expressions selected from each sub- + table. In this way, a single feature set expression is obtained + for the table. + + o In the case of the tables in sections 5.3 and 5.4, combine the + sub-table expressions with a logical-AND: (& s1 s2 ... sn ). + + o Combine the feature set expressions for each table as follows: + + (& (| T511 T512 ) T513 T52 T53 T54 ) + + where: + + - T511 is the feature set expression obtained from the table in + section 5.1.1 + + - T512 is obtained from the table in section 5.1.2 + + - T513 is obtained from the table in section 5.1.3 + + - T52 is obtained from the table in section 5.2 + + - T53 is obtained from the table in section 5.3 + + - T54 is obtained from the table in section 5.4 + + The resulting expression is the feature set expression corresponding + to the DIS bits given. Remember that there may be other capabilities + not expressed by the DIS bits that should be incorporated into the + final feature expression (e.g. TIFF image file structure). + + To do the reverse transformation, match the feature set to each row + of each decision table using the matching algorithm in RFC 2533 [2], + and OR together the DIS bit masks for each row whose feature set + expression is completely contained by (i.e. is a subset of) that + given (where the bit value in a table is 'x', use '0'). + + A feature set A is completely contained by B if the feature set match + of A and B (obtained by applying the feature set matching algorithm + in [2]) is equal to A. + + + + + + + + +McIntyre & Klyne Informational [Page 19] + +RFC 2880 Internet Fax T.30 Feature Mapping August 2000 + + +5.1 Image coding + +5.1.1 Bi-level coding + +<------- T.30 bits ---------> +15|16|31|36|37|68|69|73|78|79||Feature set expression +--+--+--+--+--+--+--+--+--+--++--------------------------------------- + x| 0| 0| | | | | | 0| 0||(& (color=binary) + | | | | | | | | | || (image-coding=[MH]) ) + x| 1| 0| | | | | | 0| 0||(& (color=binary) + | | | | | | | | | || (image-coding=[MH,MR]) + x| 0| 1| | | | | | 0| 0||(& (color=binary) + | | | | | | | | | || (image-coding=[MH,MMR]) + x| 1| 1| | | | | | 0| 0||(& (color=binary) + | | | | | | | | | || (image-coding=[MH,MR,MMR]) + x| 0| 0| | | | | | 1| 0||(& (color=binary) + | | | | | | | | | || (image-coding=[MH,JBIG]) + | | | | | | | | | || (image-coding-constraint=JBIG-T85) + | | | | | | | | | || (JBIG-stripe-size=128) ) + x| 1| 0| | | | | | 1| 0||(& (color=binary) + | | | | | | | | | || (image-coding=[MH,MR,JBIG]) + | | | | | | | | | || (image-coding-constraint=JBIG-T85) + | | | | | | | | | || (JBIG-stripe-size=128) ) + x| 0| 1| | | | | | 1| 0||(& (color=binary) + | | | | | | | | | || (image-coding=[MH,MMR,JBIG]) + | | | | | | | | | || (image-coding-constraint=JBIG-T85) + | | | | | | | | | || (JBIG-stripe-size=128) ) + x| 1| 1| | | | | | 1| 0||(& (color=binary) + | | | | | | | | | || (image-coding=[MH,MR,MMR,JBIG]) + | | | | | | | | | || (image-coding-constraint=JBIG-T85) + | | | | | | | | | || (JBIG-stripe-size=128) ) + x| 0| 0| | | | | |*1| 1||(& (color=binary) + | | | | | | | | | || (image-coding=[MH,JBIG]) + | | | | | | | | | || (image-coding-constraint=JBIG-T85) + | | | | | | | | | || (JBIG-stripe-size>=0) ) + x| 1| 0| | | | | |*1| 1||(& (color=binary) + | | | | | | | | | || (image-coding=[MH,MR,JBIG]) + | | | | | | | | | || (image-coding-constraint=JBIG-T85) + | | | | | | | | | || (JBIG-stripe-size>=0) ) + x| 0| 1| | | | | |*1| 1||(& (color=binary) + | | | | | | | | | || (image-coding=[MH,MMR,JBIG]) + | | | | | | | | | || (image-coding-constraint=JBIG-T85) + | | | | | | | | | || (JBIG-stripe-size>=0) ) + x| 1| 1| | | | | |*1| 1||(& (color=binary) + | | | | | | | | | || (image-coding=[MH,MR,MMR,JBIG]) + | | | | | | | | | || (image-coding-constraint=JBIG-T85) + | | | | | | | | | || (JBIG-stripe-size>=0) ) +--+--+--+--+--+--+--+--+--+--++--------------------------------------- + + + +McIntyre & Klyne Informational [Page 20] + +RFC 2880 Internet Fax T.30 Feature Mapping August 2000 + + +5.1.2 Multi-level coding + +<------- T.30 bits ---------> +15|16|31|36|37|68|69|73|78|79||Feature set expression +--+--+--+--+--+--+--+--+--+--++--------------------------------------- + x| | |*0| x| 0| x| x| | || +*1| | | 0| x| 1| 0| x| | ||(& (color=grey) + | | | | | | | | | || (image-coding=JPEG) + | | | | | | | | | || (image-coding-constraint=JPEG-T4E) ) +*1| | | 0| x| 1| 1| 0| | ||(& (color=[grey,full]) + | | | | | | | | | || (image-coding=JPEG) + | | | | | | | | | || (image-coding-constraint=JPEG-T4E) + | | | | | | | | | || (& (color=full) + | | | | | | | | | || (color-subsampling="4:1:1") ) ) +*1| | | 0| x| 1| 1| 1| | ||(& (color=[grey,full]) + | | | | | | | | | || (image-coding=JPEG) + | | | | | | | | | || (image-coding-constraint=JPEG-T4E) + | | | | | | | | | || (& (color=full) + | | | | | | | | | || (color-subsampling= + | | | | | | | | | || ["1:1:1","4:1:1"]) ) ) +*1| | | 1| 0|*1| 0| x| | ||(& (color=grey) + | | | | | | | | | || (image-coding=[JPEG,JBIG]) + | | | | | | | | | || (image-coding-constraint= + | | | | | | | | | || [JPEG-T4E,JBIG-T43]) + | | | | | | | | | || (image-interleave=stripe) ) +*1| | | 1| 1|*1| 0| x| | ||(& (color=grey) + | | | | | | | | | || (image-coding=[JPEG,JBIG]) + | | | | | | | | | || (image-coding-constraint= + | | | | | | | | | || [JPEG-T4E,JBIG-T43]) + | | | | | | | | | || (image-interleave=[stripe,plane]) ) +*1| | | 1| 0|*1| 1| 0| | ||(& (color=[limited,mapped,grey,full]) + | | | | | | | | | || (image-coding=[JPEG,JBIG]) + | | | | | | | | | || (image-coding-constraint= + | | | | | | | | | || [JPEG-T4E,JBIG-T43]) + | | | | | | | | | || (& (color=full) + | | | | | | | | | || (color-subsampling="4:1:1"]) ) + | | | | | | | | | || (image-interleave=stripe) ) +*1| | | 1| 0|*1| 1| 1| | ||(& (color=[limited,mapped,grey,full]) + | | | | | | | | | || (image-coding=[JPEG,JBIG]) + | | | | | | | | | || (image-coding-constraint= + | | | | | | | | | || [JPEG-T4E,JBIG-T43]) + | | | | | | | | | || (& (color=full) + | | | | | | | | | || (color-subsampling= + | | | | | | | | | || ["1:1:1","4:1:1"]) ) + | | | | | | | | | || (image-interleave=stripe) ) + + + + + + +McIntyre & Klyne Informational [Page 21] + +RFC 2880 Internet Fax T.30 Feature Mapping August 2000 + + +*1| | | 1| 1|*1| 1| 0| | ||(& (color=[limited,mapped,grey,full]) + | | | | | | | | | || (image-coding=[JPEG,JBIG]) + | | | | | | | | | || (image-coding-constraint= + | | | | | | | | | || [JPEG-T4E,JBIG-T43]) + | | | | | | | | | || (& (color=full) + | | | | | | | | | || (color-subsampling="4:1:1"]) ) + | | | | | | | | | || (image-interleave=[stripe,plane]) ) +*1| | | 1| 1|*1| 1| 1| | ||(& (color=[limited,mapped,grey,full]) + | | | | | | | | | || (image-coding=[JPEG,JBIG]) + | | | | | | | | | || (image-coding-constraint= + | | | | | | | | | || [JPEG-T4E,JBIG-T43]) + | | | | | | | | | || (& (color=full) + | | | | | | | | | || (image-coding=JPEG) + | | | | | | | | | || (color-subsampling= + | | | | | | | | | || ["1:1:1","4:1:1"]) ) + | | | | | | | | | || (image-interleave=[stripe,plane]) ) +--+--+--+--+--+--+--+--+--+--++--------------------------------------- +15|16|31|36|37|68|69|73|78|79|| +--+--+--+--+--+--+--+--+--+--++--------------------------------------- + +5.1.3 MRC format + +<---- T.30 bits ------> +15|92|93|94|95| | | ||Feature set expression +--+--+--+--+--+--+--+--++--------------------------------------- + x| 0| 0| 0| x| | | ||(MRC-mode=0) +*1| #| #| #| 0| | | ||(& (MRC-mode<=###) + | | | | | | | || (MRC-max-stripe-size=[0..256]) ) +*1| #| #| #| 1| | | ||(& (MRC-mode<=###) + | | | | | | | || (MRC-max-stripe-size>=0) ) +--+--+--+--+--+--+--+--++--------------------------------------- + + + + + + + + + + + + + + + + + + + + +McIntyre & Klyne Informational [Page 22] + +RFC 2880 Internet Fax T.30 Feature Mapping August 2000 + + +5.2 Resolution and units + +<------- T.30 bits ------> +15|41|42|43|44|45|68|97|98||Feature set expression +--+--+--+--+--+--+--+--+--++----------------------------------------- + 0| | | 0| | | | | ||(& (color=binary) + | | | | | | | | || (| (& (dpi=200) (dpi-xyratio=200/100) ) + | | | | | | | | || (& (dpi=204) + | | | | | | | | || (dpi-xyratio=204/98) ) ) ) + | | | | | | | | || + 1| | | 0| | | | | ||(| (& (color=binary) + | | | | | | | | || (| (& (dpi=204) + | | | | | | | | || (dpi-xyratio=204/98) ) + | | | | | | | | || (& (dpi=204) + | | | | | | | | || (dpi-xyratio=204/196) ) + | | | | | | | | || (& (dpi=200) + | | | | | | | | || (dpi-xyratio=200/100) ) ) ) + | | | | | | | | || (& (dpi=200) (dpi-xyratio=1) ) ) + 0| | | 1| | | | | ||(| (& (color=binary) + | | | | | | | | || (| (& (dpi=204) + | | | | | | | | || (dpi-xyratio=204/98) ) + | | | | | | | | || (& (dpi=408) + | | | | | | | | || (dpi-xyratio=408/391) ) + | | | | | | | | || (& (dpi=200) + | | | | | | | | || (dpi-xyratio=200/100) ) ) ) + | | | | | | | | || (& (dpi=400) (dpi-xyratio=1) ) ) + 1| | | 1| | | | | ||(| (& (color=binary) + | | | | | | | | || (| (& (dpi=204) + | | | | | | | | || (dpi-xyratio=204/98) ) + | | | | | | | | || (& (dpi=204) + | | | | | | | | || (dpi-xyratio=204/196) ) + | | | | | | | | || (& (dpi=408) + | | | | | | | | || (dpi-xyratio=408/391) ) + | | | | | | | | || (& (dpi=200) + | | | | | | | | || (dpi-xyratio=200/100) ) ) ) + | | | | | | | | || (& (dpi=200) (dpi-xyratio=1) ) + | | | | | | | | || (& (dpi=400) (dpi-xyratio=1) ) ) +--+--+--+--+--+--+--+--+--++----------------------------------------- + | 0| | | | | | | || + | 1| | | | | | | ||(& (color=binary) + | | | | | | | | || (dpi=204) + | | | | | | | | || (dpi-xyratio=204/391) ) +--+--+--+--+--+--+--+--+--++----------------------------------------- + | | 0| | | | | | || + | | 1| | | | | | ||(& (dpi=300) (dpi-xyratio=1) ) + + + + + + +McIntyre & Klyne Informational [Page 23] + +RFC 2880 Internet Fax T.30 Feature Mapping August 2000 + + +--+--+--+--+--+--+--+--+--++----------------------------------------- + | | x| x| | | x| 0| || + | | x| 1| | |*1| 1| ||(& (dpi=400) (dpi-xyratio=1) ) + | |*1| 0| | |*1| 1| || +--+--+--+--+--+--+--+--+--++----------------------------------------- + | | | | | | x| | 0|| + | | | | | |*1| | 1||(| (color=binary) + | | | | | | | | || (& (color=[limited,mapped,grey,full]) + | | | | | | | | || (dpi=100) (dpi-xyratio=1) ) ) +--+--+--+--+--+--+--+--+--++----------------------------------------- +15|41|42|43|44|45|68|97|98|| +--+--+--+--+--+--+--+--+--++----------------------------------------- + + Note: all numbers in media feature expressions are integer or + rational values; hence the rational number format (n/m) used here. + + Also note: the preferred unit bits (44,45) are not tested here, as a + Group 3 fax machine must accept and process either form of units for + binary images. All resolutions are expressed in dpi; here are the + metric unit equivalents: + + 204 ~= (1728/215)*25.4 ~= 8.04dpmm expressed in dpi + 408 ~= (3456/215)*25.4 ~= 16.08dpmm expressed in dpi + 98 ~= 3.85*25.4 ~= 3.85dpmm expressed in dpi + 196 ~= 7.70*25.4 ~= 7.70dpmm expressed in dpi + 391 ~= 15.40*25.4 ~= 15.40dpmm expressed in dpi + +5.3 Colour capabilities + +<------- T.30 bits ---> +36|68|69|71|74|75| | ||Feature set expression +--+--+--+--+--+--+--+--++----------------------------------------- + 0| 0| x| | | | | || + x| 1| 0| | | | | ||(| (color=binary) + | | | | | | | || (& (color=grey) + | | | | | | | || (color-space=CIELAB) ) ) + 0| 1| 1| | | | | ||(| (color=binary) + | | | | | | | || (& (color=[grey,full]) + | | | | | | | || (color-space=CIELAB) ) ) + 1|*1| 1| | | | | ||(| (color=binary) + | | | | | | | || (& (color=limited) + | | | | | | | || (color-space=[Device-RGB,Device-CMY]) + | | | | | | | || (color-levels<=8) ) + | | | | | | | || (& (color=limited) + | | | | | | | || (color-space=Device-CMYK) + | | | | | | | || (color-levels<=16) ) + | | | | | | | || (& (color=[mapped,grey,full]) + | | | | | | | || (color-space=CIELAB) ) ) + + + +McIntyre & Klyne Informational [Page 24] + +RFC 2880 Internet Fax T.30 Feature Mapping August 2000 + + +--+--+--+--+--+--+--+--++----------------------------------------- + | 0| | x| | | | || + | 1| | 0| | | | ||(| (color=[binary,limited]) + | | | | | | | || (& (color=mapped) + | | | | | | | || (color-levels<=4096) ) + | | | | | | | || (& (color=grey) + | | | | | | | || (color-levels<=256) ) + | | | | | | | || (& (color=full) + | | | | | | | || (color-levels<=16777216) ) ) + | 1| | 1| | | | ||(| (color=[binary,limited]) + | | | | | | | || (& (color=mapped) + | | | | | | | || (color-levels<=65536) ) + | | | | | | | || (& (color=grey) + | | | | | | | || (color-levels<=4096) ) + | | | | | | | || (& (color=full) + | | | | | | | || (color-levels<=68719476736) ) ) +--+--+--+--+--+--+--+--++----------------------------------------- + | 0| | | x| | | || + | 1| | | 0| | | ||(| (color=[binary,limited]) + | | | | | | | || (& (color=[mapped,grey,full]) + | | | | | | | || (color-illuminant=D50) ) ) + | 1| | | 1| | | || -- Any color illuminant: D50 or custom + | | | | | | | || -- See note below +--+--+--+--+--+--+--+--++----------------------------------------- + | 0| | | | x| | || + | 1| | | | 0| | ||(| (color=[binary,limited]) + | | | | | | | || (& (color=grey) + | | | | | | | || (CIELAB-L-min>=0) + | | | | | | | || (CIELAB-L-max<=100) ) + | | | | | | | || (& (color=[mapped,full]) + | | | | | | | || (CIELAB-L-min>=0) + | | | | | | | || (CIELAB-L-max<=100) + | | | | | | | || (CIELAB-a-min>=-85) + | | | | | | | || (CIELAB-a-max<=85) + | | | | | | | || (CIELAB-b-min>=-75) + | | | | | | | || (CIELAB-b-max<=125) ) ) + | 1| | | | 1| | || -- Any color gamut: default or custom +--+--+--+--+--+--+--+--++----------------------------------------- +36|68|69|71|74|75| | ||Feature set expression +--+--+--+--+--+--+--+--++----------------------------------------- + + NOTE: the above table assumes the registration of a feature tag + for color illuminant, values of which are tokens that are the same + as those described by ITU T.4 [7], Annex E, section E.6.7. + + + + + + + +McIntyre & Klyne Informational [Page 25] + +RFC 2880 Internet Fax T.30 Feature Mapping August 2000 + + +5.4 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| | ||Feature set expression +--+--+--+--+--+--+--+--++----------------------------------------- + 0| 0| | | | | | ||(Size-x <= 2150/254) + 1| 0| | | | | | ||(Size-x <= 2550/254) + x| 1| | | | | | ||(Size-x <= 3030/254) +--+--+--+--+--+--+--+--++----------------------------------------- + | | 0| 0| | | | ||(Size-y <= 2970/254) + | | 1| 0| | | | ||(Size-y <= 3640/254) + | | 0| 1| | | | || -- unlimited + | | 1| 1| | | | || -- invalid +--+--+--+--+--+--+--+--++----------------------------------------- + | | | | 0| 0| | ||(Paper-size=A4) + | | | | 1| 0| | ||(Paper-size=[A4,Letter]) + | | | | 0| 1| | ||(Paper-size=[A4,Legal]) + | | | | 1| 1| | ||(Paper-size=[A4,Letter,Legal]) +--+--+--+--+--+--+--+--++----------------------------------------- + +6. Examples + + NOTE: Although motivated by the requirements of eifax [5], this + document is concerned with describing capabilities of Group 3 fax + systems [6]. As such, the algorithms do not of themselves create + equivalent Internet fax capability statements but, rather, they + construct capability expressions that might be incorporated into + those for eifax systems. + + This point is illustrated at the end of the first example below where + subsection 6.1.1 has been added, which combines T.30 capabilities + with an appropriate TIFF file format capability to yield an + expression that might be used to describe an Internet fax system. + + + + + + + + + + + + + + +McIntyre & Klyne Informational [Page 26] + +RFC 2880 Internet Fax T.30 Feature Mapping August 2000 + + +6.1 Common black-and-white fax machine + + DIS/DTC + Bit No. DIS/DTC bit description Value + ------- ----------------------- ----- + 15 R8 x 7.7 lines/mm and/or 1 + 200 x 200 pels/25.4 mm + 16 Two dimensional coding capability 1 + 17,18 Recording width capabilities: 0,0 + Scan line length 215 mm + 1% + 19,20 Recording length capability: 01 + unlimited + 31 T.6 (MMR) coding capability 1 + 36 T.43 (JBIG) coding capability 0 + 37 Plane interleave 0 + 41 Resolution: 8x15.4 dpmm 0 + 42 Resolution: 300x300 dpi 1 + 43 Resolution: 16x15.4 dpmm and/or 400x400 0 + dpi + 68 JPEG coding: not supported 0 + 69 Full color mode: not supported 0 + 71 12 bits/pel component: not supported 0 + 73 No subsampling (1:1:1): not supported 0 + 74 Custom illuminant: not supported 0 + 75 Custom gamut range: not supported 0 + 76 North American Letter paper size 1 + (8.5"x11") capability + 77 North American Legal paper size 0 + (8.5"x14") capability: not supported + 78 Single-progression sequential coding 0 + (T.85, bi-level JBIG) basic capability: + not supported + 79 Single-progression sequential coding 0 + (T.85, bi-level JBIG) optional L0 + capability for other than 128 + lines/stripe: not supported + 92,93,94 T.44 (Mixed Raster Content) mode: 0,0,0 + not supported + 95 Page length maximum stripe size for MRC 0 + coding: not supported. + 97 Multi-level resolution 300x300dpi or 0 + 400x400dpi: not supported + 98 Multi-level resolution 100x100dpi: 0 + not supported + + + + + + + +McIntyre & Klyne Informational [Page 27] + +RFC 2880 Internet Fax T.30 Feature Mapping August 2000 + + + Following the procedure in section 5, matching these DIS bits + against the decision tables in sections 5.1 to 5.4, we get: + + 5.1.1 [Bits 16,31,78,79 = 1,1,0,0] + (& (color=binary) (image-coding=[MH,MR,MMR]) ) + + 5.1.2 [Bits 15,36,37,68,69,73 = 1,0,0,0,0,0] + -- no capabilities + + 5.1.3 [Bits 15,92,93,94,95 = 1,0,0,0,0] + (MRC-mode=0) + + 5.2 [Bits 15,43 = 1,0] + (| (& (color=binary) + (| (& (dpi=204) + (dpi-xyratio=204/98) ) + (& (dpi=204) + (dpi-xyratio=204/196) ) + (& (dpi=200) + (dpi-xyratio=200/100) ) ) ) + (& (dpi=200) (dpi-xyratio=1) ) ) + [Bit 41 = 0] + -- no capabilities + [Bit 42 = 1] + (& (dpi=300) (dpi-xyratio=1) ) + [Bits 42,43,68,97 = 0,0,0,0] + -- no capabilities + [Bits 68,98 = 0,0] + -- no capabilities + + 5.3 [Bits 36,68,69 = 0,0,0] + -- no capabilities + [Bits 68,71 = 0,0] + -- no capabilities + [Bits 68,74 = 0,0] + -- no capabilities + [Bits 68,75 = 0,0] + -- no capabilities + + 5.4 [Bits 17,18 = 0,0] + (size-x<=2150/254) + [Bits 19,20 = 0,1] + -- no capability constraint + [Bits 76,77 = 1,0] + (Paper-size=[A4,Letter]) + + + + + + +McIntyre & Klyne Informational [Page 28] + +RFC 2880 Internet Fax T.30 Feature Mapping August 2000 + + + Combining these as indicated in section 5, we get the following. + (The initial expression is constructed verbatim per the rules in the + first part of section 5, even though it contains some redundancy.) + + (& (| (& (color=binary) (image-coding=[MH,MR,MMR]) ) ) + (MRC-mode=0) + (| (| (& (color=binary) + (| (& (dpi=204) (dpi-xyratio=204/98) ) + (& (dpi=204) (dpi-xyratio=204/196) ) + (& (dpi=200) (dpi-xyratio=200/100) ) ) ) + (& (dpi=200) (dpi-xyratio=1) ) ) + (& (dpi=300) (dpi-xyratio=1) ) ) + (& (size-x<=2150/254) + (Paper-size=[A4,Letter]) ) ) + + This in turn is simplified as follows. Note that the expression '(& + (| (& A B ) ) C ... )' simplifies to just '(& A B C ... )'. + + (& (color=binary) + (image-coding=[MH,MR,MMR]) + (MRC-mode=0) + (| (& (dpi=204) (dpi-xyratio=204/98) ) + (& (dpi=204) (dpi-xyratio=204/196) ) + (& (dpi=200) (dpi-xyratio=200/100) ) + (& (dpi=200) (dpi-xyratio=1) ) + (& (dpi=300) (dpi-xyratio=1) ) ) + (size-x<=2150/254) + (Paper-size=[A4,Letter]) ) + +6.1.1 Corresponding Internet fax capabilities + + In the case of an Internet fax device, additional capabilities not + described by the T.30 DIS frame should be included; e.g. the + supported TIFF file structure: + + (& (color=binary) + (image-file-structure=[TIFF-Limited,TIFF-Minimal]) + (image-coding=[MH,MR,MMR]) + (MRC-mode=0) + (| (& (dpi=204) (dpi-xyratio=204/98) ) + (& (dpi=204) (dpi-xyratio=205/196) ) + (& (dpi=200) (dpi-xyratio=200/100) ) + (& (dpi=200) (dpi-xyratio=1) ) + (& (dpi=300) (dpi-xyratio=1) ) ) + (size-x<=2150/254) + (Paper-size=[A4,Letter]) ) + + + + + +McIntyre & Klyne Informational [Page 29] + +RFC 2880 Internet Fax T.30 Feature Mapping August 2000 + + +6.2 Full-featured color fax machine + + DIS/DTC + Bit No. DIS/DTC bit description Value + ------- ----------------------- ----- + 15 R8 x 7.7 lines/mm and/or 1 + 200 x 200 pels/25.4 mm + 16 Two dimensional coding capability 1 + 17,18 Recording width capabilities: 0,0 + Scan line length 215 mm + 1% + 19,20 Recording length capability: 01 + unlimited + 31 T.6 (MMR) coding capability 1 + 36 T.43 (JBIG) coding capability 0 + 37 Plane interleave 0 + 41 Resolution: 8x15.4 dpmm 1 + 42 Resolution: 300x300 dpi 0 + 43 Resolution: 16x15.4 dpmm and/or 400x400 1 + dpi + 68 JPEG coding: supported 1 + 69 Full color mode: supported 1 + 71 12 bits/pel component: not supported 0 + 73 No subsampling (1:1:1): supported 1 + 74 Custom illuminant: not supported 0 + 75 Custom gamut range: not supported 0 + 76 North American Letter paper size 1 + (8.5"x11") capability + 77 North American Legal paper size 0 + (8.5"x14") capability: not supported + 78 Single-progression sequential coding 0 + (T.85, bi-level JBIG) basic capability: + not supported + 79 Single-progression sequential coding 0 + (T.85, bi-level JBIG) optional L0 + capability for other than 128 + lines/stripe: not supported + 92,93,94 T.44 (Mixed Raster Content) mode: 0,0,1 + mode 1 supported + 95 Page length maximum stripe size for MRC 1 + coding. + 97 Multi-level resolution 300x300dpi or 1 + 400x400dpi: supported + 98 Multi-level resolution 100x100dpi: 1 + supported + + + + + + + +McIntyre & Klyne Informational [Page 30] + +RFC 2880 Internet Fax T.30 Feature Mapping August 2000 + + + Matching these DIS bits against the decision tables in sections 5.1 + to 5.4, we get: + + 5.1.1 [Bits 16,31,78,79 = 1,1,0,0] + (& (color=binary) (image-coding=[MH,MR,MMR]) ) + + 5.1.2 [Bits 15,36,37,68,69,73 = 1,0,0,1,1,1] + (& (color=[grey,full]) + (image-coding=JPEG) + (image-coding-constraint=JPEG-T4E) + (& (color=full) + (image-coding=JPEG) + (color-subsampling=["1:1:1","4:1:1"]) ) ) + + 5.1.3 [Bits 15,92,93,94,95 = 1,0,0,1,1] + (& (MRC-mode<=1) (MRC-max-stripe-size>=0) ) + + 5.2 [Bits 15,43 = 1,1] + (| (& (color=binary) + (| (& (dpi=204) + (dpi-xyratio=204/98) ) + (& (dpi=204) + (dpi-xyratio=204/196) ) + (& (dpi=408) + (dpi-xyratio=408/391) ) + (& (dpi=200) + (dpi-xyratio=200/100) ) ) ) + (& (dpi=200) (dpi-xyratio=1) ) + (& (dpi=400) (dpi-xyratio=1) ) ) + [Bit 41 = 1] + (& (color=binary) + (dpi=204) (dpi-xyratio=204/391) ) + [Bit 42 = 0] + -- no capabilities + [Bits 42,43,68,97 = 0,1,1,1] + (& (dpi=400) (dpi-xyratio=1) ) + [Bits 68,98 = 1,1] + (| (color=binary) + (& (color=[limited,mapped,grey,full]) + (dpi=100) (dpi-xyratio=1) ) ) + + 5.3 [Bits 36,68,69 = 0,1,1] + (| (color=binary) + (& (color=[grey,full]) + (color-space=CIELAB) ) ) + [Bits 68,71 = 1,0] + (| (color=[binary,limited]) + (& (color=mapped) + + + +McIntyre & Klyne Informational [Page 31] + +RFC 2880 Internet Fax T.30 Feature Mapping August 2000 + + + (color-levels<=4096) ) + (& (color=grey) + (color-levels<=256) ) + (& (color=full) + (color-levels<=16777216) ) ) + [Bits 68,74 = 1,0] + (| (color=[binary,limited]) + (& (color=[mapped,grey,full]) + (color-illuminant=D50) ) ) + [Bits 68,75 = 1,0] + (| (color=[binary,limited]) + (& (color=grey) + (CIELAB-L-min>=0) + (CIELAB-L-max<=100) ) + (& (color=[mapped,full]) + (CIELAB-L-min>=0) + (CIELAB-L-max<=100) + (CIELAB-a-min>=-85) + (CIELAB-a-max<=85) + (CIELAB-b-min>=-75) + (CIELAB-b-max<=125) ) ) + + 5.4 [Bits 17,18 = 0,0] + (size-x<=2150/254) + [Bits 19,20 = 0,1] + -- no capability constraint + [Bits 76,77 = 1,0] + (Paper-size=[A4,Letter]) + + Combining these as indicated in section 5, we get the following: + + (& (| (& (color=binary) + (image-coding=[MH,MR,MMR]) ) + (& (color=[grey,full]) + (image-coding=JPEG) + (image-coding-constraint=JPEG-T4E) + (& (color=full) + (image-coding=JPEG) + (color-subsampling=["1:1:1","4:1:1"]) ) ) + (& (MRC-mode<=1) (MRC-max-stripe-size>=0) ) + (| (| (& (color=binary) + (| (& (dpi=204) (dpi-xyratio=204/98) ) + (& (dpi=204) (dpi-xyratio=204/196) ) + (& (dpi=408) (dpi-xyratio=408/391) ) + (& (dpi=200) (dpi-xyratio=200/100) ) ) ) + (& (dpi=200) (dpi-xyratio=1) ) + (& (dpi=400) (dpi-xyratio=1) ) ) + (& (color=binary) + + + +McIntyre & Klyne Informational [Page 32] + +RFC 2880 Internet Fax T.30 Feature Mapping August 2000 + + + (dpi=204) (dpi-xyratio=204/391) ) + (& (dpi=400) (dpi-xyratio=1) ) + (| (color=binary) + (& (color=[limited,mapped,grey,full]) + (dpi=100) (dpi-xyratio=1) ) ) ) + (& (| (color=binary) + (& (color=[grey,full]) (color-space=CIELAB) ) ) + (| (color=[binary,limited]) + (& (color=mapped) (color-levels<=4096) ) + (& (color=grey) (color-levels<=256) ) + (& (color=full) (color-levels<=16777216) ) ) + (| (color=[binary,limited]) + (& (color=[mapped,grey,full]) (color-illuminant=D50) ) ) + (| (color=[binary,limited]) + (& (color=grey) + (CIELAB-L-min>=0) + (CIELAB-L-max<=100) ) + (& (color=[mapped,full]) + (CIELAB-L-min>=0) + (CIELAB-L-max<=100) + (CIELAB-a-min>=-85) + (CIELAB-a-max<=85) + (CIELAB-b-min>=-75) + (CIELAB-b-max<=125) ) ) ) + (& (size-x<=2150/254) + (Paper-size=[A4,Letter]) ) ) + + This in turn simplifies to: + + (| (& (color=binary) + (image-coding=[MH,MR,MMR]) + (MRC-mode<=1) (MRC-max-stripe-size>=0) + (| (& (dpi=204) (dpi-xyratio=204/98) ) + (& (dpi=204) (dpi-xyratio=204/196) ) + (& (dpi=204) (dpi-xyratio=204/391) ) + (& (dpi=408) (dpi-xyratio=408/391) ) + (& (dpi=200) (dpi-xyratio=200/100) ) + (& (dpi=200) (dpi-xyratio=1) ) + (& (dpi=400) (dpi-xyratio=1) ) ) + (size-x<=2150/254) + (Paper-size=[A4,Letter]) ) + (& (color=grey) + (image-coding=JPEG) + (image-coding-constraint=JPEG-T4E) + (MRC-mode<=1) (MRC-max-stripe-size>=0) + (dpi=[100,200,400]) (dpi-xyratio=1) + (color-space=CIELAB) + (color-levels<=256) + + + +McIntyre & Klyne Informational [Page 33] + +RFC 2880 Internet Fax T.30 Feature Mapping August 2000 + + + (color-illuminant=D50) + (CIELAB-L-min>=0) + (CIELAB-L-max<=100) + (size-x<=2150/254) + (Paper-size=[A4,Letter]) ) + (& (color=full) + (image-coding=JPEG) + (image-coding-constraint=JPEG-T4E) + (color-subsampling=["1:1:1","4:1:1"]) + (MRC-mode<=1) (MRC-max-stripe-size>=0) + (dpi=[100,200,400]) (dpi-xyratio=1) + (color-space=CIELAB) + (color-levels<=16777216) + (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) + (size-x<=2150/254) + (Paper-size=[A4,Letter]) ) ) + +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. Acknowledgements + + The authors gratefully acknowledge the following persons who made + comments on earlier versions of this memo: Mr. Hiroshi Tamura and + and Dr. Robert Buckley. + +9. References + + [1] Holtman, K., Mutz, A. and T. Hardie, "Media Feature Tag + Registration Procedure", RFC 2506, March 1999. + + [2] Graham, K., "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] Klyne, G. and L. McIntyre, "Content Feature Schema for Internet + Fax (V2)", RFC 2879, July 2000. + + + +McIntyre & Klyne Informational [Page 34] + +RFC 2880 Internet Fax T.30 Feature Mapping August 2000 + + + [5] Masinter, L. and D. Wing, "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 (1996), + including Amendment 1 (1997), Amendment 2 (1997), Amendment 3 + (1998) and Amendment 4 (1999) International Telecommunications + Union + + [7] "Standardization of Group 3 facsimile terminals for document + transmission" ITU-T Recommendation T.4 (1996), including + Amendment 1 (1997), Amendment 2 (1997) and Amendment 3 (1999) + International Telecommunications Union (Covers basic fax coding + formats: MH, MR; Annex E deals with some color image related + matters, including codes for optional custom illuminants. Annex + G deals with some aspects of JBIG encoding of multi-level + images.) + + [8] "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) + + [9] "Continuous-tone colour 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) + + [11] "Mixed Raster Content (MRC)" ITU-T Recommendation T.44 (1999) + International Telecommunications Union + + [12] "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) + + [13] "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) + + + + + + +McIntyre & Klyne Informational [Page 35] + +RFC 2880 Internet Fax T.30 Feature Mapping August 2000 + + + [14] "Application profile for Recommendation T.82 - Progressive bi- + level image compression (JBIG1 coding scheme for facsimile + apparatus)" ITU-T Recommendation T.85 (1995), including + Amendment 1 (1996), Amendment 2 (1997) and Corrigendum 1 (1997) + International Telecommunications Union (Covers bi-level JBIG) + + [15] Klyne, G., "Protocol-independent Content Negotiation Framework", + RFC 2703, September 1999. + + [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.) + + [17] "Mixed Raster Content (MRC) mode for G3 facsimile" ITU-T + Recommendation T.4, Annex H (1999) International + Telecommunications Union (Covers stripe size) + +10. Authors' Addresses + + 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 + + + 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 + + + + + +McIntyre & Klyne Informational [Page 36] + +RFC 2880 Internet Fax T.30 Feature Mapping August 2000 + + +11. Full Copyright Statement + + Copyright (C) The Internet Society (2000). 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