Network Working Group                                     G. Parsons
     Internet Draft                                       Nortel Networks
                                                              J. Rafferty
                                                    Brooktrout Technology
     Document: <draft-ietf-fax-tiff-regbis-00.txt>              S. Zilles
     Category: Informational                          Adobe Systems, Inc.
                                                            March 6, 2000


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

                  <draft-ietf-fax-tiff-regbis-00.txt>


     Status of this Memo

     This document is an Internet-Draft and is in full conformance
     with all provisions of Section 10 of RFC2026 except that the
     right to produce derivative works is not granted.

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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].








     Internet Draft              image/tiff               March 6, 2000

     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].


     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:
     ftp://ftp.adobe.com/pub/adobe/devrelations/devtechnotes/pdffi
     les/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.







     Internet Draft              image/tiff               March 6, 2000

     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.


     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.



     Internet Draft              image/tiff               March 6, 2000

     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.


     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.




     Internet Draft              image/tiff               March 6, 2000

          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.

          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

     Internet Draft              image/tiff               March 6, 2000

             A copy of this specification can be found in:
             ftp://ftp.adobe.com/pub/adobe/devrelations/devtechnotes/pd
             ffiles/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

             Stephen Zilles
             szilles@adobe.com

          Intended usage: COMMON

          Change controller: Stephen Zilles


     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.




     Internet Draft              image/tiff               March 6, 2000

     [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

        Stephen Zilles
        Adobe Systems Inc.
        Mailstop W14
        345 Park Avenue
        San Jose, CA 95110-2704
        USA
        Voice:  +1-408-536-4766
        Fax:    +1-408-536-4042
        Email:  szilles@adobe.com



















     Internet Draft              image/tiff               March 6, 2000
Appendix A: IANA Registration form for new values of Application
            Parameter

      To: IANA@isi.edu

      Subject: Registration of new values for the Application parameter
               of image/tiff

      MIME type name: image/tiff

      Optional Parameter: Application

      New Value(s): Application=foo

      Description of Use:

        foo - (Ofoo0 is a fictional new value used in this message as
           an example, it is to be replaced with the new value being
           registered. Include a short description of the use of the
           new value here.  This must include reference to a standards
           track RFC for the complete description;  the use of the
           value must be defined completely enough for independent
           implementation.)

      Security Considerations:

        (Any additional security considerations that may be introduced
        by useof the new parameter should be defined here or in the
        referenced standards track RFC.)

      Person & email address to contact for further information:

        Glenn W. Parsons
        gparsons@nortelnetworks.com

        James Rafferty
        jraff@brooktrout.com

        Stephen Zilles
        szilles@adobe.com


      INFORMATION TO THE SUBMITTER:

        The accepted registrations will be listed in the "Assigned
        Numbers" series of RFCs. The information in the registration
        form is freely distributable.








     Internet Draft              image/tiff               March 6, 2000

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