High Efficiency Image File Format: Difference between revisions

Revision as of 15:26, 4 December 2024

Revision as of 16:11, 4 December 2024

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* HEVC

These leadsmay lead to confusion, as users cannot easily tell what kind of encoding has been used. SimplyIn sayingparticular, thatif “HEIFa isuser creates or receives a <code>.heif</code> image, they cannot immediately determine which image encoding was used. Further, presenting HEIF as better than JPEG”JPEG asmay promotionalbe materialmisleading doesn'tsince meantruth anythingof tothat thestatement user.depends on chosen encoding.

Inside the HEIF container, JFIF (JPEG) can be stored. It can also contain AV1 encoding. The user would also need to know the encoding parameters in which the encoding happened (e.g., color quality "q", if delta in chroma planes were used, if some advanced tuning for ssim/psnr was used, or what quantization mode was applied).

If a user creates a ".HEIF" photo with their phone, the user or the receiver of the photo cannot determine which image format inside the file was used. It could be:

* a JFIF (JPEG);

* a poor quality (default settings) AV1; or

* a very high quality AV1 encoding (which takes a lot of processing power and takes a few minutes to encode); or

* an HEVC with poor quality parameters; or

* an HEVC with high quality parameters.

Hence, simply stating in promotional materials that “HEIF is better” doesn't mean anything at all, as HEIF is just a container specification. What is contained inside the container must be described.

It's impossible to easily determine exactly what you receive in HEIF container. At best, users can use graphics magic to determine if it's impossible by visual inspection (gradients transitions are broken in 8-bit photos) to tell if the photo is 12-bit or 10-bit per channel, or 8-bit.

{{anchor|MIAF}}{{anchor|MPEG-A}}

=== MIAF ===

The Multi-Image Application Format (MIAF) is a restricted subset of HEIF specified as part of [[MPEG-A]].

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.<ref name="MIAF">{{citation |title= ISO/IEC 23000-22. Multimedia application format (MPEG-A) — Part 22: Multi-image application format (MIAF) |publisher= ISO/IEC MPEG |url= https://www.iso.org/standard/74417.html |access-date= 2020-04-29 |archive-date= 2020-04-26 |archive-url= https://web.archive.org/web/20200426173836/https://www.iso.org/standard/74417.html |url-status= live }}</ref>

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[[H.264/MPEG-4 AVC|Advanced Video Coding]] (AVC, ITU-T H.264) is an older encoding format for video and images, first standardized in 2003.

It is also specified as a codec to be supported in HEIF in normative Annex 5 to ISO/IEC 23008-12.

The registered MIME types are <code>image/avci</code> for still images and <code>image/avcs</code> for sequences. The format is simply known as AVCI.