It defines a set of additional constraints to simplify format options, specific alpha plane formats, profiles and levels as well as metadata formats and brands, and rules for how to extend the format. The Multi-Image Application Format (MIAF) is a restricted subset of HEIF specified as part of MPEG-A. heif, but they may use a different extension to indicate the specific codec used. Generic HEIF image files are typically stored with filename extensions. heifs for sequences, which can both be used with any codec. Variants Īs HEIF is a container format, it can contain still images and image sequences that are coded in different formats. Image metadata Storage of EXIF, XMP and similar metadata which accompany the images stored in the HEIF file. These data are not displayed as such, but used in various forms to complement another image item. Auxiliary image items Storage of image data, such as an alpha plane or a depth map, which complements another image item. Hence, file sizes can be drastically reduced when many images are stored in the same HEIF file. Different prediction options can be used in order to exploit the temporal and spatial similarities between the images. Image sequences Storage of multiple time-related and/or temporally predicted images (like a burst-photo shot or cinemagraph animation), their properties and thumbnails. The storage overhead of derived images is small. These instructions (rectangular cropping, rotation by one, two or three quarter-turns, timed graphic overlays, etc.) and images are stored separately in the HEIF file, and describe specific transformations to be applied to the input images. Image derivations Derived images enable non-destructive image editing, and are created on the fly by the rendering software using editing instructions stored separately in the HEIF file. HEIF files can store the following types of data: Image items Storage of individual images, image properties and thumbnails. On some systems, pictures stored in the HEIC format are converted automatically to the older JPEG format when they are sent outside of the system, although incompatibility has led to problems such as US Advanced Placement test takers failing due to their phones uploading unsupported HEIC images by default leading the College Board to request students change the settings to send only JPEG files. Īpple was the first major adopter of the format in 2017 with the introduction of iOS 11 using HEIC variant. The technical development of the specification took about one and a half years and was finalized in the middle of 2015. The requirements and main use cases of HEIF were defined in 2013.
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