Tag Image File Format (TIFF) - image/tiff MIME Sub-type Registration
obsoleted by
- rfc-3302 — Tag Image File Format (TIFF) - image/tiff MIME Sub-type Registration
Extracted elements (12)
The image/tiff definition is re-scoped from RFC 1528's narrow reference to TIFF Class F to encompass all TIFF 6.0 profiles and extensions, consistent with existing practice for TIFF-aware Internet applications. This broadening reflects the reality that many deployed applications use TIFF beyond Class F.
There is no default value for the application parameter; its absence indicates the image is Baseline TIFF or that identifying the application is unnecessary. The parameter is intended to assist recipient dispatch to a suitable rendering package, not to convey capability levels.
Implementations may not be able to handle all defined TIFF application profiles, potentially decoding and attempting display only to find the image cannot be rendered. The application parameter can help identify this incompatibility before dispatching for rendering.
The application parameter value is not intended to convey levels of capabilities for a particular application; it only identifies which TIFF subset applies to the encoded data.
Encoding of image/tiff content should use Binary or Base-64 transfer encoding.
New values for the application parameter should be defined in standards-track RFCs and registered with IANA using the registration form in Appendix A.
An optional 'application' parameter is introduced for the image/tiff content-type to identify the specific TIFF subset or extension profile applicable to the encoded image data. Example: 'Content-type: image/tiff; application=foo'. No values are defined in this document.
Appendix A defines an IANA registration form for new values of the 'application' parameter of image/tiff. Submissions must include a description of use with reference to a standards-track RFC and any additional security considerations introduced by the new value.
RFC 2302 formally registers the MIME media type image/tiff with IANA, covering all profiles and extensions that build on TIFF 6.0 encoded image data. The registration supersedes the earlier definition in RFC 1528, which was limited to TIFF Class F.
The fields defined in the TIFF specification are descriptive in nature and do not induce any particular behavior by the recipient application, so they do not in themselves create additional security risks.
TIFF's extensible structure means fields could theoretically be defined in the future that induce recipient actions and present security risks; however, this capability is not supported in TIFF 6.0 and would be inconsistent with the goals of the specification.
TIFF files are identified by magic numbers: little-endian (II) files begin with 0x49 0x49 0x42 0x00; big-endian (MM) files begin with 0x4D 0x4D 0x00 0x42. File extension is .TIF; Macintosh file type code is TIFF.