Network Working Group L. McIntyre
Request for Comments: 3950 Consultant
Obsoletes: 3250 G. Parsons
Category: Standards Track Nortel Networks
J. Rafferty
Brooktrout Technology
February 2005
Tag Image File Format Fax eXtended (TIFF-FX) - image/tiff-fx
MIME Sub-type Registration
Status of this Memo
This document specifies an Internet standards track protocol for the
Internet community, and requests discussion and suggestions for
improvements. Please refer to the current edition of the "Internet
Official Protocol Standards" (STD 1) for the standardization state
and status of this protocol. Distribution of this memo is unlimited.
Copyright Notice
Copyright (C) The Internet Society (2005).
Abstract
This document describes the registration of the MIME sub-type
image/tiff-fx. The encodings are defined by File Format for Internet
Fax and its extensions.
1. Introduction
This document describes the registration of the MIME sub-type
image/tiff-fx. The encodings are defined by File Format for Internet
Fax [TIFF-FX] and its extensions.
This document is a product of the IETF Internet Fax Working Group.
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 BCP 14, RFC 2119
[REQ].
2. TIFF-FX Definition
Tag Image File Format Fax eXtended (TIFF-FX), is defined in detail by
RFC 3949, "File Format for Internet Fax" [TIFF-FX].
McIntyre, et al. Standards Track [Page 1]
RFC 3950 image/tiff-fx February 2005 While a brief scope and feature description is provided in this section as background information, the reader is directed to the original TIFF-FX specification (File Format for Internet Fax) to obtain complete feature and technical details. 2.1. TIFF-FX Scope This document defines a TIFF-based file format specification for enabling standardized messaging-based fax over the Internet. It specifies the TIFF fields and field values required for compatibility with the existing ITU-T Recommendations for Group 3 black-and-white, grayscale and color facsimile. TIFF has historically been used for handling fax image files in applications such as store-and-forward messaging. Implementations that support this file format specification for import/export may elect to support it as a native format. This document recommends a TIFF file structure that is compatible with low-memory and page-level streaming implementations. Unless otherwise noted, the current TIFF specification [TIFF] and selected TIFF Technical Notes [TTN1, TTN2] are the primary references for describing TIFF and defining TIFF fields. This document is the primary reference for defining TIFF field values for fax applications. 2.2. TIFF-FX Features Some of the features of TIFF-FX are: - TIFF-FX is capable of describing bilevel, grayscale, palette- color, full-color and mixed content image data. - TIFF-FX includes a number of compression schemes that allow developers to choose the best space or time tradeoff for their applications. - TIFF-FX is designed to be extensible and to evolve gracefully as new needs arise. 3. MIME Definition This document defines the image/tiff-fx MIME sub-type to refer to TIFF-FX Profiles J, C, L and M encoded image data and any future TIFF-FX extensions, or a subset. The image/tiff-fx content type MAY be used when black-and-white image data is encoded using TIFF-FX Profiles S or F, or a subset, however, the image/tiff content type SHOULD be used. McIntyre, et al. Standards Track [Page 2]
RFC 3950 image/tiff-fx February 2005 4. IANA Registration To: ietf-types@iana.org Subject: Registration of Standard MIME media type image/tiff-fx MIME media type name: image MIME subtype name: tiff-fx Required parameters: none Optional parameters: none Encoding Considerations: This media type consists of binary data. The base64 encoding should be used on transports that cannot accommodate binary data directly. Security considerations: TIFF-FX utilizes a structure which can store image data and attributes of this image data. The fields defined in the TIFF-FX 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-FX 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-FX 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-FX specification. Indeed, the definition of fields which would include such processing instructions is inconsistent with the goals and spirit of the TIFF-FX specification. The MIME type and file extension defined by this document MUST NOT be used to blindly select a processing program. It is up to the implementation to determine the application (if necessary) and render the image to the user. McIntyre, et al. Standards Track [Page 3]
RFC 3950 image/tiff-fx February 2005 Interoperability considerations: The ability of implementations to handle all the defined applications (or profiles within applications) of TIFF-FX may not be ubiquitous. As a result, implementations may decode and attempt to display the encoded TIFF-FX image data only to determine that the image cannot be rendered. Published specification: TIFF-FX (Tag Image File Format Fax eXtended) is defined in: RFC 3949, "File Format for Internet Fax", February 2005, Buckley, R., Venable, D., McIntyre, L., Parsons, G., and J. Rafferty. Applications which use this media type: Imaging, fax, messaging and multi-media Additional information: Magic number(s): II (little-endian): 49 49 2A 00 hex MM (big-endian): 4D 4D 00 2A hex File extension(s): .TFX Macintosh File Type Code(s): TFX Person & email address to contact for further information: Lloyd McIntyre Lloyd_McIntyre@Dell.com Glenn W. Parsons gparsons@nortelnetworks.com James Rafferty jraff@brooktrout.com Intended usage: COMMON Change controller: Lloyd McIntyre McIntyre, et al. Standards Track [Page 4]
RFC 3950 image/tiff-fx February 2005 5. Security Considerations TIFF-FX utilizes a structure which can store image data and attributes of this image data. The fields defined in the TIFF-FX 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-FX 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-FX 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-FX specification. Indeed, the definition of fields which would include such processing instructions is inconsistent with the goals and spirit of the TIFF-FX specification. The MIME type and file extension defined by this document MUST NOT be used to blindly select a processing program. It is up to the implementation to determine the application (if necessary) and render the image to the user. 6. References 6.1. Normative References [TIFF-FX] Buckley, R., Venable, D., McIntyre, L., Parsons, G., and J. Rafferty, "File Format for Internet Fax", RFC 3949, February 2005. 6.2. Informative References [TIFF] Adobe Developers Association, TIFF (TM) Revision 6.0 - Final, June 3, 1992. [REQ] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [TTN1] Adobe PageMaker 6.0 TIFF Technical Notes, Sept. 14, 1995, http://partners.adobe.com/asn/developer/pdfs/tn/TIFFPM6.pdf [TTN2] Adobe Photoshop TIFF Technical Notes, Replacement TIFF/JPEG specification, March 22, 2002, http://partners.adobe.com/asn/developer/pdfs/tn/ TIFFphotoshop.pdf McIntyre, et al. Standards Track [Page 5]
RFC 3950 image/tiff-fx February 2005 Annex A. List of edits to RFC 3250 +----+---------+-------------------------------------------------+ | No.| Section | Edit | +----+---------+-------------------------------------------------+ | 1. | All | Updated references from RFC 2301 to | | | | draft-ietf-fax-tiff-fx-13.txt | +----+---------+-------------------------------------------------+ | 2. | 5 | MIME Definition - added a "SHOULD" statement to | | | | stress that image/tiff is the preferred content | | | | type when representing Profiles S and/or F. | +----+---------+-------------------------------------------------+ | 3. | 7 | Revise security considerations. | +----+---------+-------------------------------------------------+ | 4. | 3 | Merged sections 2 & 3 and renumbered. | +----+---------+-------------------------------------------------+ McIntyre, et al. Standards Track [Page 6]
RFC 3950 image/tiff-fx February 2005 Authors' Addresses Lloyd McIntyre 10328 S. Stelling Road Cupertino, CA 95014 USA Phone: +1-408-725-1624 EMail: lloyd10328@pacbell.net or Lloyd_McIntyre@Dell.com Glenn W. Parsons Nortel Networks P.O. Box 3511, Station C Ottawa, ON K1Y 4H7 Canada Phone: +1-613-763-7582 Fax: +1-613-967-5060 EMail: gparsons@nortel.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 McIntyre, et al. Standards Track [Page 7]
RFC 3950 image/tiff-fx February 2005
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McIntyre, et al. Standards Track [Page 8]
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