draft-ietf-fax-tiff-regbis-03.txt

Network Working Group                                        G. Parsons
Internet Draft                                          Nortel Networks
Document: <draft-ietf fax-tiff-regbis-03.txt>               J. Rafferty
Obsoletes: RFC 2302                               Brooktrout Technology
Category: Best Common Practice                         November 5, 2001


               Tag Image File Format (TIFF) - image/tiff
                       MIME Sub-type Registration

                  <draft-ietf-fax-tiff-regbis-03.txt>


Status of this Memo

   This document is an Internet-Draft and is in full conformance with
   all provisions of Section 10 of RFC2026.

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1. Abstract


   This document describes the registration of the MIME sub-type
   image/tiff.  The baseline encoding is defined by [TIFF].  This
   document refines an earlier sub-type registration in RFC 1528
   [TPC.INT].

   This document obsoletes RFC2302.


2.  Conventions used in this document


   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED",  "MAY", and "OPTIONAL" in
   this document are to be interpreted as described in RFC-2119 [REQ].





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3.  Overview


   This document describes the registration of the MIME sub-type
   image/tiff.  The baseline encoding is defined by [TIFF].


4.  Internet Fax Working Group


   This document is a product of the IETF Internet Fax Working Group.
   All comments on this document should be forwarded to the email
   distribution list at <ietf-fax@imc.org>.


5.  TIFF Definition


   TIFF (Tag Image File Format) Revision 6.0 is defined in detail by
   Adobe in [TIFF].  The documentation can be obtained from Adobe at:

      Adobe Developers Association
      Adobe Systems Incorporated
      345 Park Avenue
      San Jose, CA 95110-2704

      Phone: +1-408-536-6000
      Fax:   +1-408-537-6000

   A copy of this specification can also be found in:
   http://partners.adobe.com/asn/developer/PDFS/TN/TIFF6.pdf

   While a brief scope and feature description is provided in this
   section as background information, the reader is directed to the
   original TIFF specification [TIFF] to obtain complete feature and
   technical details.


5.1  TIFF Scope


   TIFF describes image data that typically comes from scanners, frame
   grabbers, and paint- and photo-retouching programs. TIFF is not a
   printer language or page description language. The purpose of TIFF
   is to describe and store raster image data.  A primary goal of TIFF
   is to provide a rich environment within which applications can
   exchange image data. This richness is required to take advantage of
   the varying capabilities of scanners and other imaging devices.
   Though TIFF is a rich format, it can easily be used for simple
   scanners and applications as well because the number of required
   fields is small.








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5.2  TIFF Features


   Some of the features of TIFF (from [TIFF]) are:

    - TIFF is capable of describing bilevel, grayscale, palette-color,
      and full-color image data in several color spaces.

    - TIFF includes a number of compression schemes that allow
      developers to choose the best space or time tradeoff for their
      applications.

    - TIFF is designed to be extensible and to evolve gracefully as new
      needs arise.

    - TIFF allows the inclusion of an unlimited amount of private or
      special-purpose information.


6.  MIME Definition


6.1  image/tiff


   The image/tiff content-type was previously defined in RFC1528 as
   containing TIFF 6.0 encoded image data, with specific reference made
   to a subset known as TIFF Class F. This document redefines the
   original image/tiff definition to refer to TIFF 6.0 [TIFF] encoded
   image data, consistent with existing practice for TIFF aware
   Internet applications. This definition is further enhanced by
   introducing the new "application parameter" (section 6.2) to enable
   identification of a specific subset of TIFF and TIFF extensions for
   the encoded image data.


6.2  Application parameter


   There are cases where it may be useful to identify the application
   applicable to the content of an image/tiff body. 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. As a result, an optional "application" parameter is defined
   for image/tiff to identify a particular application's subset of TIFF
   and TIFF extensions for the encoded image data, if it is known. No
   values are defined in this document.


   Example:

                Content-type: image/tiff; application=foo

   There is no default value for application, as the absence of the
   application parameter indicates that the encoded TIFF image is
   Baseline TIFF or that it is not necessary to identify the
   application. It is up to the recipient's implementation to determine
   the application (if necessary) and render the image to the user.

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   New values for the image/tiff application parameter must be approved
   by the IESG prior to registration. As a result, the publication of a
   description of parameter values in an RFC is required.

   Guidelines on writing IANA considerations for RFCs can be found in
   RFC 2434.



7.  IANA Registration


        To: ietf-types@iana.org
        Subject: Registration of Standard MIME media type image/tiff

        MIME media type name: image

        MIME subtype name: tiff

        Required parameters: none

        Optional parameters: application

           There is no format specified for the value of this parameter
           in addition to that specified by [MIME1].  Various
           applications of TIFF may define values as required.  There
           is no default value for application, as the absence of the
           application parameter indicates that the encoded TIFF image
           is Baseline TIFF or that it is not necessary to identify the
           application.  It is up to the implementation to determine
           the application (if necessary) and render the image to the
           user.

        Encoding considerations: Binary or Base-64 generally preferred

        Security considerations:

           TIFF utilizes a structure which can store image data and
           attributes of this image data. The fields defined in the
           TIFF specification are of a descriptive nature and provide
           information that is useful to facilitate viewing and
           rendering of images by a recipient.  As such, the fields
           currently defined in the TIFF specification do not in
           themselves create additional security risks, since the
           fields are not used to induce any particular behavior by the
           recipient application.

           TIFF has an extensible structure, so that it is
           theoretically possible that fields could be defined in the
           future which could be used to induce particular actions on
           the part of the recipient, thus presenting additional
           security risks, but this type of capability is not supported
           in the referenced TIFF specification. Indeed, the definition
           of fields which would include such processing instructions
           is inconsistent with the goals and spirit of the TIFF
           specification.


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        Interoperability considerations:

           The ability of implementations to handle all the defined
           applications (or profiles within applications) of TIFF may
           not be ubiquitous. As a result, implementations may decode
           and attempt to display the encoded TIFF image data only to
           determine that the image cannot be rendered. The presence of
           the application parameter may aid in allowing this
           determination before dispatching for rendering.  However, it
           should be noted that the parameter value is not intended to
           convey levels of capabilities for a particular application.

        Published specification:

           TIFF (Tag Image File Format) is defined in:
               TIFF (TM) Revision 6.0 - Final _ June 3, 1992

           Adobe Developers Association
           Adobe Systems Incorporated
           345 Park Avenue
           San Jose, CA 95110-2704

           Phone: +1-408-536-6000
           Fax:   +1-408-537-6000

           A copy of this specification can be found in:
           ftp://ftp.adobe.com/pub/adobe/devrelations/devtechnotes/pdff
           iles/tiff6.pdf

        Applications which use this media type:

           Imaging, fax, messaging and multi-media

        Additional information:

           Magic number(s):
                II (little-endian):  49 49 42 00 hex
                MM (big-endian):     4D 4D 00 42 hex
           File extension(s): .TIF
           Macintosh File Type Code(s): TIFF

        Person & email address to contact for further information:

           Glenn W. Parsons
           gparsons@nortelnetworks.com

           James Rafferty
           jraff@brooktrout.com

        Intended usage: COMMON

        Change controller: James Rafferty





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8. References


   [REQ] Bradner, S., "Key words for use in RFCs to Indicate
        Requirement Levels", BCP 14, RFC 2119, March 1997.

   [MIME1] N. Freed and N. Borenstein,  "Multipurpose Internet Mail
        Extensions (MIME) Part One: Format of Internet Message Bodies",
        RFC 2045, Innosoft, First Virtual, Nov 1996.

   [MIME4] N. Freed and N. Borenstein,  "Multipurpose Internet Mail
        Extensions (MIME) Part Four: Registration Procedures", RFC
        2048, Innosoft, First Virtual, Nov 1996.

   [TIFF] Adobe Developers Association, TIFF (TM) Revision 6.0 - Final,
        June 3, 1992.

   [TPC.INT] C. Malamud, M. Rose, "Principles of Operation for the
        TPC.INT Subdomain:  Remote Printing -- Technical Procedures",
        RFC 1528, 10/06/1993


9. Author's Addresses

      Glenn W. Parsons
      Nortel Networks
      P.O. Box 3511, Station C
      Ottawa, ON  K1Y 4H7
      Canada
      Phone: +1-613-763-7582
      Fax:   +1-613-763-2697
      Email: gparsons@nortelnetworks.com

      James Rafferty
      Brooktrout Technology
      410 First Avenue
      Needham, MA  02494
      USA
      Phone: +1-781-433-9462
      Fax:   +1-781-433-9268
      Email: jraff@brooktrout.com



















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