High Efficiency Image File Format (HEIF) specifies the storage of individual images as well as image sequences in a single container file. It is an MPEG standard and defined by part 12 of MPEG-H (ISO/IEC 23008-12).
HEIF specification defines the means of storing High Efficiency Video Codec (HEVC) encoded intra images and HEVC encoded image sequences in which inter prediction is applied in a constrained manner. HEIF files are compatible with the ISO Base Media File Format (ISOBMFF, ISO/IEC 14496-12) and can also include other media streams, such as timed text and audio.
History
The requirements and main use cases of HEIF were defined in 2013 [1][2].The technical development of the specification took about 1.5 years and was finalized in summer 2015[3].
Use Cases
Some main use cases supported by HEIF are as follows[1][2]:
- Storage of single or multiple images and their thumbnails,
- Storage of burst photos,
- Support for simultaneous capture of video and still images, i.e. storing still images and timed image sequences into the same file,
- Efficient representation of animations and cinemagraphs,
- Storage of focal and exposure stacks into the same container file,
- Storage of images derived from other images of the file, either as derived images represented by non-destructive image editing operations or as pre-computed derived images,
- Support for storing other media, such as audio and timed text, into the same container file with timed image sequences and synchronizing their playback.
As HEVC provides support for various chroma formats and sample fidelities up to lossless coding, the format can serve the whole spectrum of use cases from today's consumer devices storing images typically at 8 bits per sample to high-end professional devices with sample fidelity and dynamic range requirements going all the way up to 16 bits per sample. Some usage scenarios that are facilitated by HEIF are described below:
Digital cameras and smartphones:
In order to save storage space [TODO: x-ref to compression results], HEIF-encapsulated HEVC-coded images can be used for compressing the full-resolution images while keeping a lower-resolution JPEG copy (e.g. at 4K resolution or below) for on-screen displaying purposes.
Digital cameras and smartphones can use HEIF to achieve convenient one-file packaging of burst photos, focal stacks, and exposure stacks. Similarly, simultaneously captured video and still images can be stored in the same HEIF file. HEIF also enables storage of any image collections into a single file, hence they can be shared easily.
Web pages and Internet-connected image applications:
The picture element of HTML5.1 provides the capability of indicating multiple alternatives for the same image, out of which the web browser can select the one that best suits its purpose. A motivation for web pages and connected applications to start using HEIF is to reduce the web page and/or image content download times [x-ref to compression results].
References
- ^ a b "Requirements for still image coding using HEVC | MPEG". mpeg.chiariglione.org. Retrieved 2015-11-25.
- ^ a b "Requirements for HEVC image sequences | MPEG". mpeg.chiariglione.org. Retrieved 2015-11-25.
- ^ "Evidence motivates MPEG to launch new standardization effort for HDR".