Network Working Group G. Parsons
Request for Comments: 2302 Northern Telecom
Category: Standards Track J. Rafferty
Human Communications
S. Zilles
Adobe Systems, Inc.
March 1998
Tag Image File Format (TIFF) - image/tiff
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 (1998). All Rights Reserved.
Overview
This document describes the registration of the MIME sub-type
image/tiff. The baseline encoding is defined by [TIFF].
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>.
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].
2. 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:
Parsons, et. al. Standards Track [Page 1]
RFC 2302 TIFF March 1998 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/pdffiles/ 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. 2.1 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. 2.2 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. Parsons, et. al. Standards Track [Page 2]
RFC 2302 TIFF March 1998 3. MIME Definition 3.1 image/tiff The image/tiff content-type was previously defined in RFC 1528 as containing TIFF 6.0 encoded image data, with specific reference made to a subset known as TIFF Class F. This document re-defines the original image/tiff definition to refer to all of the profiles and extensions that build on 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 3.2) to enable identification of a specific subset of TIFF and TIFF extensions for the encoded image data. 3.2 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 using a fictional value 'foo': 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. 4. 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 Parsons, et. al. Standards Track [Page 3]
RFC 2302 TIFF March 1998 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. New values should be defined in standards track RFCs and the values should be registered with IANA, using the registration form included in Appendix A. 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. 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 Parsons, et. al. Standards Track [Page 4]
RFC 2302 TIFF March 1998 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 Glenn.Parsons@Nortel.ca James Rafferty Jrafferty@worldnet.att.net Stephen Zilles szilles@adobe.com Intended usage: COMMON Change controller: Stephen Zilles Parsons, et. al. Standards Track [Page 5]
RFC 2302 TIFF March 1998 5. Authors' Addresses Glenn W. Parsons Northern Telecom P.O. Box 3511, Station C Ottawa, ON K1Y 4H7 Canada Phone: +1-613-763-7582 Fax: +1-613-763-2697 Email: Glenn.Parsons@Nortel.ca James Rafferty Human Communications 12 Kevin Drive Danbury, CT 06811-2901 USA Phone: +1-203-746-4367 Fax: +1-203-746-4367 Email: Jrafferty@worldnet.att.net 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 6. 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. [TIFF] Adobe Developers Association, TIFF (TM) Revision 6.0 - Final, June 3, 1992. [TPC.INT] Malamud, C. and M. Rose, "Principles of Operation for the TPC.INT Subdomain: Remote Printing -- Technical Procedures", RFC 1528, October 1993. [TIFFPLUS] McIntyre, L., Zilles, S., Buckley, R., Venable, D., Parsons, G., and J. Rafferty, "File Format for Internet Fax", RFC 2301, March 1998. [TIFF] Parsons, G., and J. Rafferty, "Tag Image File Format TIFF) -- R Profile for Facsimile, RFC 2306, March 1998. Parsons, et. al. Standards Track [Page 6]
RFC 2302 TIFF March 1998 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 - ("foo" 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 use of the new parameter should be defined here or in the referenced standards track RFC.) Person & email address to contact for further information: (fill in contact information) 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. Parsons, et. al. Standards Track [Page 7]
RFC 2302 TIFF March 1998
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Parsons, et. al. Standards Track [Page 8]
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