With iOS 11, Apple on the iPhone and iPad changes to new codecs for pictures and videos. Instead of using JPEG and H.264, newer devices will use HEIF and HEVC (H.265) in the future. Especially HEIF brings some advantages with the recording of photos, from which also developers profit. A brief overview.
HEVC stands for High Efficiency Video Coding and has established itself as the standard on the Ultra HD Blu-ray. The codec allows a higher compression rate with the same or higher image quality. Usually, a compression factor of two is referred to as H.264 in HEVC, so that a film with fourfold resolution fits twice as much in comparison to the Blu-ray Ultra HD Blu-ray. The codec is also suitable for higher resolution than 4K.
High Efficiency Image Format
While Apple will switch to HEVC with video footage with iOS 11, it is HEIF that will replace JPEG. HEIF stands for High Efficiency Image Format and is designed to meet modern requirements. Also HEIF promises smaller files with the same or higher picture quality. The advantage over JPEG can also be achieved here by halving the file size.
HEIF creates JPEG artefacts
How good HEIF against JPEG and GIF truncates, can be seen clearly on a GitHub of Nokia. With comparable file size, HEIF offers clearly less artifacts, which are typical for JPEG compression, especially in the detailed view in all tested situations. Subjectively, the image quality of HEIF is better seen, although the image is somewhat soft.
Compression and quality are but two of the many positive features of HEIF, the format is above all more versatile than JPEG. In HEIF, for example, several images can be stored in a file, and additional image information can be stored. These include an alpha channel for transparency, a depth map and a thumbnail.
Save more information
For a smartphone with two lenses like the iPhone 7 Plus (test), Apple can store the depth information directly in the HEIF file and use it for future image manipulation or make this information available to developers and their apps. With JPEG, it was previously only possible to save the calculated image with bokeh, but not to change it later. With the depth information, for example, only the background in black and white can be changed afterwards. If desired, the background can also be completely exchanged for another. Apple demonstrated during its developer’s “Platforms State of the Union” keynote a sample app that puts a virtual sunglasses on a person with a guitar and inserts a roaring audience as a background.
Apple’s ecosystem remains compatible with the rest
But what makes Apple, if HEVC and HEIF should communicate devices with those that do not support the new formats? Like last year’s switch to the expanded display P3 color space, videos and images outside the Apple ecosystem are shared in the older formats H.264 and JPEG – for example, in an e-mail or printing station. A name for it does not exist yet, in Display-P3 it was called Apple Wide Color Sharing Profile. Within the framework of the WWDC, further information about the camera can be expected in the coming days.