Type name: image Subtype name: ktx Required parameters: none Optional parameters: none Encoding considerations: binary Security considerations: The ktx type is a binary data stream which contains no executable code that could disrupt a client processor. There is no provision in the type specification that would allow authors to insert executable code that would present any security risk to a client machine. Because every item's length is available at its beginning, there is robust defense against corrupted or fraudulent data that might overflow a decoder's buffer. Also the signature bytes provide early detection of common file transmission errors. The ktx type may contain texture data compressed using OpenGL standard or vendor-specific schemes. These compression schemes are designed so small blocks of data (typically around 64 bits) can be decompressed in real time into a small block of pixels (typically 4x4) during texel fetch. In such schemes it is not possible for a small amount of data to expand enormously because the level of compression is limited; the compressed size is related directly to the number of pixels in the uncompressed image and not to the content of the data. The ktx type does not provide encryption of the data payload. Users or applications wishing or needing to keep their images confidential must overlay their own encryption on the ktx data during transmission. Interoperability considerations: The ktx type includes a field identifying the endianness of the machine which created the data. Applications reading the data are expected to check this field and convert the endianness, if necessary. The texture data payload may be compressed using an OpenGL-vendor-specific scheme. In this case, only devices or applications having a matching decompressor will be able to display the data. The compression scheme is identified in the ktx data so applications can quickly reject data using unsupported schemes. Published specification: The KTX file format specification can be found at http://www.khronos.org/opengles/sdk/tools/KTX/file_format_spec/. Applications that use this media type : Currently only etcpack. It is anticipated it will be widely used by applications built on top of the OpenGL family of standards, OpenGL, OpenGL ES and WebGL, as the means of delivering texture data. Additional information: Magic number(s): 12 octets - { 0xAB, 0x4B, 0x54, 0x58, 0x20, 0x31, 0x31, 0xBB, 0x0D, 0x0A, 0x1A, 0x0A } File extension(s): .ktx Macintosh file type code(s): Person & email address to contact for further information: Mark Callow (callow_mark at hicorp.co.jp) Intended usage: COMMON Restrictions on usage: none Authors: Mark Callow, Georg Kolling, Jacob Ström Change controller: The Khronos Group, the industry consortium responsible for standards such as OpenGL, OpenGL ES, WebGL and OpenCL.