(registered 2019-05-17, last updated 2019-05-17) Type name: image Subtype name: jphc Required parameters: N/A Optional parameters: N/A Encoding considerations: binary Security considerations: HTJ2K codestreams contain structures of variable length and have an extensible syntax. Both of these 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: HTJ2K codestreams do not contain information on the colourspace of the image. This information is implied or provided out-of-band. Published specification: Rec. ITU-T T.814 | ISO/IEC 15444-15 Applications: Multimedia and scientific Fragment identifier considerations: N/A Restrictions on usage: N/A Provisional registration: No Additional information: N/A Magic number(s): Starts with the following 4-byte sequence: 0xFF 0x4F 0xFF 0x51 File extension(s): jhc Macintosh File Type Code(s): N/A Object Identifiers: N/A Contact name: ISO/IEC JTC 1/SC 29/WG 1 Convenor Contact email address: sc29-sec&itscj.ipsj.or.jp Intended usage: COMMON Change controller: ITU-T & ISO/IEC JTC 1