rfc2306.txt

著名的RFC文档,其中有一些文档是已经翻译成中文的的.

   The minimum subset of values are also shown. If required fields are
   omitted in a TIFF-F file, the Baseline TIFF default value will apply.
   Image data must not have any coding errors. In the table, certain
   fields have a value that is a sequence of flag bits (e.g. T4Options).
   An implementation should test the setting of the relevant flag bits
   individually to allow extensions to the sequence of flag bits to be
   appropriately ignored.





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   As noted within [TIFF], a TIFF file begins with an 8-byte image file
   header, of which the first two bytes (0-1) contain the byte order
   within the file.  The permissible values are:

       II- Byte order from least significant byte to the most
           significant byte (little-endian)
       MM - byte order is always from most significant to least
           significant (big-endian)

   For a TIFF-F Reader, the legal values are:

       ByteOrder: MM,II (Either byte order is allowed)

3.9.1.1  Fields for TIFF-F Reader

   Recommended Fields in the table are shown with an asterisk (*).

   Other fields may be present, but they should be of an informational
   nature, so that a reader can elect to ignore them.

   Informational fields which are often present in TIFF-F images are:
      Software, Datetime, BadFaxLines, CleanFaxData and
      ConsecutiveBadFaxLines.

  Field             | Values      | Minimum     | Comment
  ------------------|-------------|-------------|----------------------
  BitsPerSample     | 1           | 1           |one bit per sample
  Compression       | 3,4         | 3           |3 for T.4 (MH, MR)
                    |             |             |4 for T.6 - MMR
  FillOrder         | 2,1         | 2           |LSB first or MSB first
  ImageWidth        | 1728, 2048, | 1728        |depends on XResolution
                    | 2432, 2592, |             |
                    | 3072, 3648, |             |
                    | 3456, 4096, |             |
                    | 4864        |             |
  ImageLength       | >0          |             |required
  NewSubFileType    | Bit 1 = 1   | Bit 1 = 1   |single page of
                    |             |             |multipage file
  Orientation *     | 1           |             |1st row=top left,
                    |             |             | 1st col=top
  PageNumber        | X/X         | 0/1         |pg/tot, 0 base,
                    |             |             | tot in 1st IFD
  PhotometricInterp | 0,1         | 0           |0 is white
  ResolutionUnit    | 2,3         | 2           |inches (default)
  RowsPerStrip      |=ImageLength |=ImageLength |
                    | or other    |             |
  SamplesPerPixel   | 1           | 1           |one sample per pixel
  StripByteCounts   | >0          |             |required



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  StripOffsets      | >0          |             |required
  T4Options         | Bit 0 = 0,1 | Bit 0 = 0   |MH,MR(incl if not MMR)
                    | Bit 1 = 0   | Bit 1 = 0   |
                    | Bit 2 = 0,1 | Bit 2 = 0,1 | Non-Byte-aligned and
                    |             |             | Byte-Aligned EOLs
  T6Options         | 0           |             |MMR (incl only if MMR)
  XResolution       | 204,200,300,| 204         | If unit is per inch
                    | 400,408,    |             |
                    | 77          |             | If unit is per cm
  YResolution       | 196,98,100, | 196,98      | If unit is per inch
                    | 200,300,391,|             |
                    | 400,        |             |
                    | 77,38.5     |             | If unit is per cm
  ------------------|-------------|-------------|----------------------

3.9.2  TIFF-F Writer

   For the case of writing (creating) a TIFF-F file format from an image
   data stream or other raster data, implementations SHOULD write files
   which can be read by a TIFF-F Reader as defined in 3.9.1.  It is
   recommended that all fields from the table in 3.9.1.1 SHOULD be
   included when writing TIFF-F files in order to  minimize dependencies
   on default values. Image data must not have any coding errors.

   Other fields may be present, but they should be of an informational
   nature, so that a Reader may elect to ignore them.

   For the case of writing "minimum subset" TIFF-F files, the rules
   defined in section 3.6 apply.

   Informational fields that may be useful for TIFF-F files are:
       Software, Datetime, BadFaxLines, ConsecutiveBadFaxLines

   TIFF Writers SHOULD only generate the fields that describe facsimile
   image quality when the image has been generated from a fax image data
   stream where error correction (e.g. Group 3 Error Correction Mode)
   was not used.  These fields are:  CleanFaxData, BadFaxLines and
   ConsecutiveBadFaxLines.

4.  MIME sub-type image/tiff

   [TIFFREG] describes the registration of the MIME content-type image/
   tiff to refer to TIFF 6.0 encoded image data.   When transported by
   MIME, the TIFF content defined by this document must be encoded
   within an image/tiff content type. In addition, an optional
   "application" parameter is defined for image/tiff to identify a
   particular application's subset of TIFF and TIFF extensions for the




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   encoded image data, if it is known. Typically, this would be used to
   assist the recipient in dispatching a suitable rendering package to
   handle the display or processing of the image file.

4.1 Refinement of MIME sub-type image/tiff for Application F

   Since this document defines a facsimile specific profile of TIFF, it
   is useful to note an appropriate application parameter for the
   image/tiff MIME content-type.

   The "faxbw" application parameter is defined for black and white
   facsimile.  It is suitable for use by applications that can process
   one or more TIFF for facsimile profiles or subsets used for the
   encoding of black and white facsimile data.

   Since this document defines a profile of TIFF for facsimile which is
   suitable for use with black and white facsimile image data,
   applications which use this profile or its minimum subset should set
   the value of the application parameter to "faxbw".

   An example of the use of the image/tiff MIME Content-type with the
   application parameter set with the value "faxbw" follows:

   Example:

          Content-type: image/tiff; application=faxbw

   In this example, use of this parameter value will enable applications
   to identify the content as being within a profile or subset of TIFF
   for Facsimile that is suitable for encoding black and white image
   data, before attempting to process the image data.

5.  Implementation Usage

   5.1 Internet Fax Usage

   The usage of TIFF-F is envisioned as a component of Internet Fax.  It
   is anticipated that Internet Fax may use both a TIFF-F Reader and
   TIFF-F Writer. The details of the Internet Fax services and their use
   of TIFF-F will be specified in other documents.

5.2 VPIM Usage

   The Application F of TIFF (i.e. TIFF-F content) is a secondary
   component of the VPIM Message as defined in [VPIM2].  Voice messaging
   systems can often handle fax store-and-forward capabilities in
   addition to traditional voice message store-and- forward functions.




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   As a result, TIFF-F fax messages can optionally be sent between
   compliant VPIM systems, and may be rejected if the recipient system
   cannot deal with fax.

   Refer to the VPIM Specification for proper usage of this content.

6.  Security Considerations

   This document describes the encoding for TIFF-F, which is a profile
   of the TIFF encoding for facsimile.  As such, it does not create any
   security issues not already identified in [TIFFREG], in its use of
   fields as defined in [TIFF]. There are also new TIFF fields defined
   within this specification, but they are of a purely descriptive
   nature, so that no new security risks are incurred.

   Further, the encoding specified in this document does not in any way
   preclude the use of any Internet security protocol to encrypt,
   authenticate, or non-repudiate TIFF-F encoded facsimile messages.

7.  Authors' Addresses

   Glenn W. Parsons
   Northern Telecom
   P.O. Box 3511, Station C
   Ottawa, ON  K1Y 4H7
   Canada
   Phone: [phone]
   Fax:   [phone]
   Email: [e-mail]

   James Rafferty
   Human Communications
   12 Kevin Drive
   Danbury, CT 06811-2901
   USA
   Phone: [phone]
   Fax:   [phone]
   Email: [e-mail]

8. References

   [MIME1] Freed, N. and N. Borenstein,  "Multipurpose Internet Mail
        Extensions (MIME) Part One: Format of Internet Message Bodies",
        RFC 2045, November 1996.
   [MIME4] Freed, N. and N. Borenstein,  "Multipurpose Internet Mail
        Extensions (MIME) Part Four: Registration Procedures", RFC 2048,
        November 1996.




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   [REQ] Bradner, S., "Key words for use in RFCs to Indicate
        Requirement Levels", RFC 2119, March 1997.
   [T.30] ITU-T Recommendation T.30 - "Procedures for Document
        Facsimile Transmission in the General Switched Telephone
        Network", June, 1996
   [T.4] ITU-T Recommendation T.4 - "Standardization of Group 3
        Facsimile Apparatus for Document Transmission", June, 1996
   [T.6] ITU-T Recommendation T.6 - "Facsimile Coding Schemes and
        Coding Control Functions for Group 4 Facsimile Apparatus",
        March, 1993
   [TIFF] Adobe Developers Association, TIFF (TM) Revision 6.0 -
        Final, June 3, 1992.
   [TIFFREG] Parsons, G., Rafferty, J. and S. Zilles, "Tag Image File
        Format (TIFF) - image/tiff:  MIME Sub-type Registration ", RFC
        2302, March 1998.
   [VPIM2] G. Vaudreuil and G. Parsons, "Voice Profile for Internet
        Mail - version 2", Work In Progress, <draft-ema-vpim-06.txt>,
        November 1997.

































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9.  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.

   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.
























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