HEIF Format Explained

Nasim Mansurov

With the rise of digital content on the Internet, it is becoming more and more important to have an efficient image format. One such format is HEIF, which is designed to be as small as possible while retaining high image quality. In this article, we will take a closer look at HEIF format, including its variants like HEIC, and see how it differs from other image formats such as JPEG, GIF, and PNG.

iPhone 11 Pro Image Sample #71
Image originally captured in HEIF format, edited in Lightroom and exported to JPEG
iPhone 11 Pro Max @ 1.54mm, ISO 200, 1/120, f/2.4

What is HEIF Format?

HEIF stands for High-Efficiency Image File format, which is basically a container that is capable of storing an image, or a sequence of images in a single file. Designed to be extremely lightweight and efficient, the HEIF format can store images at a very high compression ratio that is about twice more efficient than an equivalent-quality JPEG image. HEIF is based on High Efficiency Video Coding (HEVC) standard.

Being a container, it can be used to store image sequences, such as a GIF animation or an HDR sequence.  The HEIF format was developed by the Moving Picture Experts Group (MPEG), under the ISO / IEC 23008-12 standard in 2015. Since then, it has been adopted by a number of manufacturers, including Apple, Microsoft, and Canon. Apple introduced HEIF as the default image and video format in iOS 11 using the HEIC variant, which pushed companies to support it in their software, including Adobe.

Still images stored in HEIF format have a .heif file extension, while image sequences have a .heifs extension. Depending on the variant and codec used (see more below), extensions can change. The most common variant today is HEIC, which uses HEVC / H.265 video format for compressing content.

HEIF Data Storage

Compared to simple image formats like JPEG, the HEIF format is able to store a lot of different types of images and data, including:

In this sense, it is highly versatile, as it can combine the power of several image formats such as JPEG, PNG, and GIF in a single file while preserving high image quality.

High Efficiency Video Coding (HEVC)

High Efficiency Video Coding (HEVC), which is also known as H.265, is a video compression standard that offers up to 50% better data compression levels compared to its H.264 predecessor. The first version of HEVC was approved for standardization in 2013, and the latest HEVC version 4 was approved as an ITU-T standard in late 2016. Since then, HEVC has been widely adopted by many software and hardware companies. Today, most modern CPUs and GPUs are able to hardware-encode / decode HEVC content.

HEVC is used as the default codec in HEIF, which is why the resulting files are much smaller when compared to other formats. Apple uses HEVC exclusively for its HEIF content, which goes by the name “High Efficiency Image Coding” (HEIC).

High Efficiency Image Coding (HEIC)

As pointed out earlier, there are a number of variants of HEIF, which can be used to store images, sequences of images, or videos using different codecs. The variant that Apple uses in its iOS and macOS operating systems is High Efficiency Image Coding (HEIC), which uses HEVC / H.265 for content compression. To differentiate image and image sequence files from video content in its devices, Apple uses the .heic file extension. For HEVC-encoded video content, Apple continues to use the .mov file extension.

HEIC vs JPEG

It is important to point out that HEIC has many advantages when compared to JPEG. While JPEG always produces lossy 8-bit images (even at the highest quality setting), HEIC can store images up to 16-bit, lossy or lossless. This makes HEIC similar in its potential to the original RAW file, something JPEG cannot even remotely compete with. And best of all, it can store all this data very efficiently, resulting in comparably small file sizes. How small? Let’s take a look.

To compare HEIC with JPEG format, I grabbed five very detailed images that I captured with my iPhone 11 Pro Max. Since Apple converts images to HEIC using very high quality setting (roughly 8th bar in the Quality slider), I converted all images using the same JPEG quality setting. To make sure that there is no quality loss, I loaded both files into Photoshop at viewed them at 100% zoom – they looked identical, with no added artifacts on either image. Take a look at the below before / after of the two:

As you can see, there is no visual difference between the two.

Here are the original HEIC files:

HEIC Total: 16.8 MB

And here are the converted JPEG files:

JPEG Total: 27.0 MB

As you can see, the space savings with the HEIC files are fairly significant. The resulting JPEG files were 60% larger in comparison – that’s quite a bit of wasted storage!

Having previously gone through all of my JPEG images with JPEGmini Pro and significantly reducing their sizes, I wanted to see what kind of file savings I could get if I used this tool on top of the above JPEG files. Below are the results:

JPEGmini Total: 14.9 MB

JPEGmini was able to optimize JPEG files even better than HEIC’s HEVC compression, which is pretty impressive. This shows that if you have a bunch of JPEG images that you want to make smaller, you might be better off using JPEGmini, instead of bothering to convert your JPEG files to HEIC.

But if your original files are already in HEIC format, it is probably best to keep them as-is. Apple uses a fairly high quality setting with HEIC files, which is roughly equivalent to the 8th bar in the Quality slider of the Preview app.

HEIF Compatibility

The good news is that both Apple and Microsoft provide support for the HEIF in their operating systems, so opening files and viewing them should not be a problem.

All iOS devices loaded with iOS 11 and later are able to software-decode HEIF content and HEIC images. However, only devices with Apple’s A9 chip and later are able to hardware-decode HEIF content. To hardware-decode HEIC images and 8-bit video content on a Mac, you will need to use Intel’s 6th Generation and newer CPUs, while 10-bit video content will require 7th Generation and newer Intel CPUs.

If you use a PC, you will need to use Windows 10 and update it to April 2018 Update and higher to be able to software-decode HEIF content.

The bad news is that support for Internet browsers and third-party post-processing tools is coming rather slowly. Unless you use a popular app like Lightroom or Affinity Photo, you might need to wait until HEIF support is provided in your favorite software. In the meantime, you will need to use native and third-party conversion tools to convert HEIF files to a common format like JPEG.

OS Support

The following operating systems support HEIF content:

Note that while Microsoft provides support for HEIF files in Windows 10, you have to buy this extension for $0.99 in order to be able to software and hardware-decode HEVC-compressed content.

Browser Support

The only browser that supports the HEIC format is Safari for MacOS and iOS.

To view HEIC images on other browsers such as Firefox, Edge, and Chrome/Chromium, you must install third-party extensions.

Post-Processing Application Support

The following post-processing software has built-in support to be able to read and edit HEIC images:

Note that HEVC / H.265 support for video files is provided in Lightroom CC 2.0 and Lightroom Classic CC 8.0 and newer releases.

How to Convert HEIC to JPEG Images

If you have a HEIC image and you need to convert it to a JPEG image, you can use any of the above post-processing tools to open the source HEIF image, then simply export it as a JPEG file. We go over this process for Adobe Lightroom Classic CC in our Lightroom Export Settings tutorial.

If you use a Mac, you can easily batch-convert HEIC images to JPEG by using the Preview app. Simply select the group of images you want to convert, open them in Preview app, then select all images by pressing CMD + A. From there, go to File -> Export Selected Images… click the Options button, select “JPEG” in the Format drop-down field, pick your quality level and click the “Choose” button to export to a specific folder:

If you use a PC, there are a number of free software tools like the iMazing HEIC converter that you can download to convert HEIC images.

Alternatively, you can use free online converters to convert HEIC to JPEG images. But you have to be careful – many of them strip the original EXIF data from the source HEIC images. We recommend using the HEICtoJPG.com service, which was developed by the same folks who made JPEGmini. This free conversion tool will not only convert HEIC images, but it will also compress the resulting JPEG file using the JPEGmini engine while retaining full EXIF data.

Summary

Without a doubt, HEIF is an excellent choice when compared to JPEG, GIF, PNG and other image formats. It is a versatile format, because it allows storing all kinds of media – from single images and sequences, to video. Thanks to the superb compression levels of HEVC / H.265, HEIF files end up being significantly smaller when compared to other image formats like JPEG, or previous video formats like H.264, while retaining the same or better image quality levels.

It is great to see that Apple, Canon, Fuji and other manufacturers are moving to adopt the HEIF format. I can’t wait to see more camera manufacturers implement HEIF in their devices in the future. I would also love to see native browser support for HEIF files, so that we could start transitioning away from the limited JPEG format.

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