MPEG claims that HEIF images can be up to 50 percent smaller than an equivalent JPEG. It isn’t hard to see why, after knowing the benefits it offers. With iOS 11, Apple switched to using HEIF by default for storing the photos captured by the camera. It is also possible to store auxiliary information like an alpha channel, a thumbnail, or a depth map. These are images stored with a set of instructions in the file that dictate how to apply edits to said file in software. With HEIF, in addition to storing simple single images, one can also store “derivations” of the original. We’ll use these terms interchangeably throughout the post. According to Apple, the file extension for single-image HEIF files is HEIC. In this post, we’re going to be looking at the performance of HEIF when used to store a single image. While we’re confident about the compression and quality attributes of HEIF, the coding performance surprised us, in that it was significantly slower than when using JPEG. Additionally, it should be decoded and encoded quickly on a mobile device.

For us, the cached image needs to be as accurate as possible while also not occupying too much space.

At PSPDFKit, we cache rendered PDF pages on disk using JPEG. In introducing it with iOS 11 (and macOS 10.13), Apple claims that bitmaps stored as HEIF files are of a higher quality than a JPEG that occupies more space on disk. High Efficiency Image File Format (HEIF) is a file format for storing multiple types of image data developed by the Moving Picture Experts Group (MPEG).

Heic image viewer decoder