(registered 2019-05-17, last updated 2019-05-17)

Media type name: image

Media subtype name: hej2k

Required parameters: None

Optional parameters: Same as for the media type image/heif. The 
   presence of an image item of type 'j2ki' is signalled by 
   including, in the itemtypes parameter, an item description whose 
   item type string starts with 'j2ki'.

Encoding considerations: binary

Security considerations: See media type image/heif. In addition, 
   image items of type 'j2ki' contain structures of variable length 
   and have an extensible syntax. Both aspects present potential 
   security risks for implementations. In particular, variable length
   structures present buffer overflow risks and extensible syntax 
   could result in the triggering of adverse actions.

Interoperability considerations: Same as for the media type 
   image/heif. In addition, image items of type 'j2ki' can conform to
   one of several profiles and/or require one of several 
   capabilities, e.g. as specified in Rec. ITU-T T.800 | ISO/IEC 
   15444-1, not all of which are necessarily supported by a receiving
   decoder. As a result, decoders might attempt to process the 
   contents only to determine that they cannot be rendered either 
   partially or in full.

Published specification: Rec. ITU-T T.815 | ISO/IEC 15444-16.

Applications which use this media: Multimedia and scientific

Fragment identifier considerations: Same as for the media type 
   image/heif.

Restrictions on usage: None.

Additional information:

   1. Deprecated alias names for this type: N/A 
   2. Magic number(s): None.
   3. File extension(s): hej2
   4. Macintosh file type code: N/A
   5. Object Identifiers: N/A

Person to contact for further information:

   1. Name: ISO/IEC JTC 1/SC 29/WG 1 Convenor 
   2. Email: sc29-sec&itscj.ipsj.or.jp

Intended usage: Common

Author/Change controller: ITU-T & ISO/IEC JTC 1