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Understanding New Image Formats

Akamai Image & Video Manager (IVM) already supports key modern image types, such as WebP, JPEG 2000, and JPEG XR, but the imaging industry is always evolving and raising the bar on the balance of compression and quality. In addition, creative and development teams are regularly asking about new formats, and it's important to understand the leading ones. In this article, we'll examine two newer image formats that are gathering momentum: High-Efficiency Image File (HEIF) and AV1 Image File (AVIF).

The creation of new image types is typically driven by three main objectives:

  • Better compression that requires fewer bytes for the same image quality
  • Enhanced features to support a wider range of use cases, such as animations and transparencies, within a single image format
  • Increased browser support for compatibility with the highest percentage of users

Let's look at both HEIF and AVIF formats through the lens of these objectives.

HEIF

Developed by the Moving Pictures Experts Group (MPEG) in 2013, this image format is based on the High-Efficiency Video Codec (HEVC) and is heavily backed by Apple.

Compression

MPEG claims that this image format provides two times the compression of JPEG without lower visual fidelity. As shown in the article "Comparison: HEIF vs JPEG in iOS 11" by Apowersoft, the following images in HEIF and JPG format are 1.2 MB and 2.5 MB, respectively.

ImageFormatsBlog1_1Dec.png

Source: Apowersoft

Enhanced Features 

HEIF provides one of the most robust sets of advanced features among image formats. It allows the storage of:

  • Still images as well as collections of images in a single container file
  • Burst photos
  • Video animations and cinemagraphs as well as their efficient representations
  • Still images and timed image sequences into the same file with support for simultaneous capture of video and still images
  • Images derived from other images of the file, either as derived images represented by nondestructive image editing operations or as pre-computed derived images
  • Focal and exposure stacks into the same container file
  • Other media, such as audio and timed text, into the same container file, with timed image sequences and synchronized playback

Browser Support 

One of the main reasons we still work with GIF, JPEG, and PNG image formats is their universal browser support. This is one of the current drawbacks of HEIF. While the underlying HEVC format has some native browser support in Safari, not even this browser has native support for HEIF. Until reasonable browser support is available, our guidance is to experiment with HEIF, but not widely deploy this image format.

ImageFormatsBlog2_1Dec.pngSource: caniuse.com

AVIF

Developed by the Alliance for Open Media, this royalty-free image format is backed by many big players, including Google, Netflix, Adobe, Mozilla, Microsoft, Facebook, and Amazon. Based on the AV1 video codec, AVIF is currently still considered experimental and not appropriate for production use.

Compression 

AVIF image format promises higher compression than any current image format, including WebP, as can be seen from the following violin graph, which compares image file size savings in WebP and AVIF to the reference JPEG at the same image similarity. Larger negative numbers indicate higher compression:

ImageFormatsBlog3_1Dec.pngSource: Ctrl.blog

Enhanced Features

An AVIF file is basically an AV1 key frame packed inside a container, similar to the HEIF structure, except AVIF uses the AV1 video format instead of HEVC. Some of its advanced features support:

  • High dynamic range and standard dynamic range images
  • Wide color gamut images
  • Monochrome as well as multichannel images
  • Multilayer images
  • Image items and image sequences

Browser Support 

One of the current drawbacks with AVIF is its limited browser support. However, there have been some recent positive developments. As you can see in the table, Chrome now supports AVIF, beginning in Version 85. In addition, Mozilla began working on adding AVIF support to Firefox in January 2020.

ImageFormatsBlog4_1Dec.pngSource: Caniuse

While still not universally supported by leading browsers, AVIF/AV1 have good chances to gain wider support, as all major browser vendors are part of the Alliance for Open Media, including Apple and Google, and there is hope that there will be less of a "format war" as we've seen with WebM/WebP or HEIF.

Follow the Trends

Image optimization is an ever-changing and evolving science. As such, it's important to be educated about new trends to encourage informed technology decisions. We also recommend that you ensure your image provider will support these formats sooner rather than later.

In our next article, we'll discuss two emerging video formats that are gathering momentum: High-Efficiency Video Codec (HEVC) and AOMedia Video 1 (AV1).