HEIC

Every photo on a phone is saved as a file. The format of this file determines how the image information is packed into zeros and ones. HEIC is one of these formats, recognizable by the “.heic” extension after the file name. It was developed to store images far more space-efficiently than JPEG, the format that has been common since the 1990s. A photo that takes up four megabytes as a JPEG often needs only two as a HEIC. Usually, it doesn’t look noticeably worse.

Why Apple brought the format to every iPhone

Storage space on phones is expensive, and people take a lot of photos. Anyone with 20,000 images on their device saves several gigabytes with HEIC. That’s why Apple switched the camera on all newer iPhones to HEIC by default in 2017 with iOS 11. Since then, the format has been the norm on hundreds of millions of devices, without most owners ever having consciously chosen it.

The price for this is compatibility. A format is only useful if the other side can open it. Older Windows versions, many website uploads, print systems at copy shops, and some school platforms still can’t handle .heic to this day. This is exactly where the most common encounter with the term comes from: someone sends a photo, and the recipient sees an error message instead of the image.

For the tech industry, HEIC is also a lesson in how difficult it is to switch standards. JPEG is technically outdated by now, but it works everywhere. A better format doesn’t succeed on better numbers alone — it only catches on once enough software adopts it. With HEIC, that has taken years and still isn’t complete today.

Video compression applied to a single image

The trick behind HEIC is borrowed. The format uses the compression method HEVC, which was actually developed for video. Video codecs are extremely good at recognizing areas that look similar and describing them only once. A HEIC image is essentially treated like a video made of a single frame. This means a still photo benefits from decades of research into moving images.

As with JPEG, information that the eye barely notices is discarded in the process. This is called lossy compression. HEIC just makes these decisions more cleverly and in finer gradations. It also stores colors with up to 16 bits per channel instead of the 8 bits used by JPEG, which avoids visible banding in sunsets.

The “C” stands for container. A HEIC file can contain more than just one image: multiple shots from a burst, transparency, depth information for portrait mode, or the short motion clips of a Live Photo. Strictly speaking, the standard is called HEIF, and HEIC is the variant using HEVC compression. In everyday use, the terms are mostly used interchangeably.

When the image won’t open for the recipient

HEIC most often gets noticed in a negative way. A photo ends up on someone else’s computer via email or USB stick and won’t open. There are two settings for this in the iPhone settings: under “Camera – Formats,” you can switch to “Most Compatible,” and the device will go back to taking photos in JPEG. When sharing, you can also set it to automatically convert during transfer.

When sending via WhatsApp, Instagram, or iMessage, none of this is noticeable because these services convert the images themselves anyway. The format mainly becomes visible in direct file exchanges: job application portals, government forms, school uploads. Anyone who gets rejected there due to an “invalid file type” has usually run into a HEIC.

A related name also comes up in tech news: AVIF. This is a competing format with a similar goal, but it is license-free. HEVC carries patent fees, which holds back many manufacturers. As a result, AVIF has tended to prevail on the web, while HEIC has remained the format used for camera storage.