True HDR photography is the future of still photography and presents an exciting opportunity to bring your camera RAW files alive and let people see what they have been missing with standard JPEGs. However, making your first steps requires getting to grips with the complex set of HDR image formats available.
In this article, I discuss the available image file options so that you can assess their roles within your own workflow. I show that the very best format is JPEG XL in terms of capabilities, HDR image quality and file sizes. I show lossless JPEG XL can be at the heart of a very effective workflow, particularly for Apple users. Bloated and artifact-ridden Gain-Mapped JPEG is by far the worst format available. The formats covered are JPEG with embedded Gain Map (sometimes known as Ultra HDR), JPEG XL (or JXL), AVIF and HEIC/HEIF.
Basic JPEG, which is over 33 years old, is a tough act to follow due to its widespread adoption even though it’s not very good by modern standards
Before discussing image formats for HDR images, it is worth understanding the critical role conventional 8-bit JPEGs have played in digital photography since the early 1990s. It also helps to explain how we have ended up with multiple HDR image formats, including the flawed gain-mapped JPEG format (discussed in the next section).
The Joint Photographic Experts Group (JPEG) was formed in 1986 to create a standard for image compression. At the time, displays were extremely limited in their peak brightness and the range of colours they could display. The final JPEG standard was published and approved in 1992. The importance of JPEG cannot be overstated. Suiting perfectly display technologies at the time, the 8-bit JPEG format has delivered manageable file sizes for images displayed on websites and allowed the widespread sharing of photographs.
It is now over 33 years since the 8-bit JPEGs was standardised. Over the years, as would be expected, despite its widespread prevalence, the standard JPEG format has become increasingly outdated. JPEG compression algorithms, which were considered relatively advanced in the early 1990s, are now considered outdated and inefficient. JPEG can suffer from noticeable image imperfections and artifacts, and file sizes are larger than they need to be. With a standard 8-bit JPEG, each pixel has a level assigned to each colour channel (Red, Green and Blue). 8 bits allows for only 256 levels (0-255) per channel, with a total of only 16.8 million colours. As well as limited colour range, the limited number of levels severely restricts the dynamic range (i.e. the difference in light levels between the brightest and darkest parts of a scene) that can be stored or displayed.
While limitations in colour range and dynamic range were not significant issues in the 1990s, modern digital cameras (using RAW formats) can now capture many more colours and much greater dynamic range than the standard 8-bit JPEG can handle. Furthermore, modern HDR-capable displays can deliver much higher peak brightness levels (and dynamic range) and a greater range of colours than displays could in the 1990s.
True HDR photography is all about seizing the opportunity from modern camera sensors and displays to store, edit, share and display images with many more colours and dynamic range that more closely match human sight. So, despite the prevalence of 8-bit JPEG, new, so-called next-generation image formats, are now necessary to deliver the true HDR photography ‘experience’.
Unfortunately, unlike in the 1990s, when the one JPEG format became the de-facto standard for photographs, several formats currently exist – each with their own strengths and weaknesses. As will be discussed, a major challenge with all these new formats is being able to deliver superior images to devices that support them while continuing to deliver acceptable images to all the devices not capable of displaying these superior images. The long-term success and proliferation of the standard 8-bit JPEG format have created major challenges for any image format(s) that come after it.
Gain-Mapped JPEG (to display HDR images) is a flawed format, which prioritises JPEG compatibility over image quality, breadth of colours and file sizes
I start with my least favourite (by far) HDR-capable image format, and that is JPEG with an embedded Gain Map. It is also termed Ultra HDR. Unfortunately, this is a hack rather than a genuine native HDR image format, like JPEG XL and AVIF, discussed later. This format embeds a conventional standard dynamic range 8-bit JPEG image with a Gain Map (a second grayscale image) that essentially tells compatible devices how to brighten specific parts of the image to effectively create an HDR image. The supposed benefit of this approach is that the format can be read by legacy systems, which simply see a conventional 8-bit JPEG file, while compatible systems are able to read the additional Gain Map and construct an HDR image.
JPEG with a Gain Map is not a true HDR format. While I am happy to champion true HDR photography as a means of displaying higher quality images with high dynamic range and a wider set of colours, I struggle with the idea of supporting the use of manipulated 8-bit JPEGs, which continue to only use the limited sRGB colour space. While the use of the format allows 100% of devices to be able to read the 8-bit JPEG image, the price paid for this compatibility is far too high. I certainly won’t be using this format personally.
From a performance and efficiency standpoint, JPEG with a Gain Map is a terrible format for HDR images for several reasons:
- Higher dynamic ranges and improved colours necessitate using more bits per pixel in an image. Rather than 8 bits with JPEG, true HDR formats need at least 10 bits. This is why HDR video standards use at least 10-bit encoding. Trying to construct an HDR image from the 8 bits of a JPEG is plain silly.
- The compression algorithms used with JPEG are outdated, and new formats, such as AVIF and JPEG XL, achieve much higher levels of compression and/or quality, with smaller file sizes. A focus on JPEG with a Gain Map means less focus on image formats that will deliver better quality HDR images and faster webpage loading times.
- Visual compression artifacts and banding using JPEG are significantly worse for an HDR image than for a standard SDR image. While this can be improved to a certain extent by increasing the quality level in the compression process, this will typically significantly increase the size of the JPEG file. Also, do we really want a format that doesn’t deliver HDR images in excellent quality?
- Adding a Gain Map further increases the size of the file. With the effect of having to reduce image compression (to lessen artifacts with HDR content), file sizes can be substantially higher than conventional JPEGs. My own tests show that Gain Mapped JPEGs are at least double the size of AVIF or JPEG XL files for similar HDR image quality. Given that true HDR formats such as AVIF and JPEG XL support HDR, improve image quality and reduce file sizes, it seems that the Gain-Mapped JPEG is a major step backwards.
- Gain-mapped JPEG is a truly awful format to choose to archive HDR images. Rather than keeping unedited RAW files, many photographers choose to keep a set of post-edit images in the best quality they can. Often, they do not want to return to, and re-edit, RAW files so keeping a high-quality edited HDR image can be very useful. Using Gain-Mapped JPEG for this purpose is a terrible idea. Enhanced colour information will be lost, visual artifacts will be introduced (such as banding), image detail will be lost (due to poor compression) and file sizes will be higher than they need to be. When you have the hugely superior lossless JPEG XL format (discussed below), why would you choose Gain-Mapped JPEG?
Services like Google Photos and Apple Photos/iCloud blur the line between image archiving and image display, and can be very useful for photographers. However, when Google Photos currently only supports Gain-Mapped JPEG, surely this is going to encourage some photographers to use this inadequate format for archiving purposes?
Web designers have a decision as to whether they add HDR images to their site(s) and to choose an appropriate format. There seems little sense to me of choosing Gain-Mapped JPG since HDR images will not look as good as they could and file sizes will be considerably larger than conventional JPEGs for all users, increasing page sizes and loading times. Surely, they would choose a format (such as AVIF) that can offer excellent HDR (and SDR) images while reducing page loading times at the same time. With AVIF, all users – whether or not they have compatible devices – would benefit from faster page loading.
The existence of Gain-Mapped JPEG may lead to significant unnecessary effort by photographers and web designers to use bloated image files that are already outdated and will need to be replaced with superior, true HDR image formats. The sooner JPEG with Gain Map format no longer exists, the better! Everyone should focus on speeding up the transition to true next-generation HDR image formats, such as JPEG XL and AVIF. Adopting a half-baked image format threatens the future evolution towards, and success of, true HDR photography. Photographers will only be tempted to enter the world of true HDR photography when they see clear visual benefits from doing so.
I tried to directly compare the Gain-Mapped JPEG with Gain-Mapped AVIF. Here is the AVIF file with dimensions 2000×1333 pixels and file size of only 88kB.
I then produced a Gain-Mapped JPEG image with the same dimensions, and the resulting size was 246 kB – nearly three times the AVIF file size. Despite the huge increase in file size, close inspection of the Gain-Mapped JPEG image reveals noticeable artifacts that are absent on the much smaller AVIF image, as shown below.
Quite frankly, Gain-Mapped JPEG is a terrible format.
JPEG XL is the best overall true HDR image format, but browser support (Chrome) is currently a weakness although not a limitation for its use
We go from my least favourite image format – JPEG with Gain Map – to my favourite – JPEG XL or JXL. JPEG XL is a very exciting format because it delivers an unbeatable set of benefits. It is the format of choice for True HDR Photography. It forms the basis of my own True HDR Photography workflow.
JPEG XL is a free, open standard – published in 2022 – that has been created by the JPEG committee to replace the ageing JPEG format. It supports lossy and lossless compression. JPEG XL represents an ideal choice for archiving HDR (and non-HDR) images of all types.
JPEG XL is perfect for encoding both photographs (with much better compressions than the old JPEG format) and graphics (with much better compression than the PNG format). It is possible to transcode existing JPEG files, reducing size by about 20%, without any loss of original data. These files can be restored to their exact original JPEG format, so the JPEG XL format is completely backwards-compatible.
In lossy mode, JPEG XL images can be up to 60% smaller than traditional JPEGs for the same visual quality. For photographers, a huge advantage of JPEG XL is that it offers a lossless mode. So, photographers can edit RAW files and save them in lossless JPEG XL form without worrying about any loss of information from the conversion. From these, they can easily produce smaller, lossy images in either JPEG XL or AVIF for use on the Web or any other purpose.
Adobe Camera RAW can already output both lossy (with a range of quality levels) and lossless JPEG XL files.
Apple users currently have a major advantage – the early support and adoption of JPEG XL by Apple. Apple Photos supports JPEG XL files and, can therefore, display them perfectly on compatible HDR displays, including iPhones, iPads and Macbooks Pros. Apple ic clearly leading with next-generation image support, with many of its applications directly supporting JPEG XL (including its Safari browser, Apple Photos, Apple Keynote and Apple Final Cut Pro). The latest Apple iPhones now store RAW images in lossless JPEG XL format.
In November 2025, the PDF Association selected JPEG XL as the preferred image format of future PDFs.
For some peculiar reason, Google decided, in October 2022, to not proceed with previous experimental support for JPEG XL in its Chrome browser. It was a silly decision, and Google reversed this decision in November 2025. Probably due to its earlier decision, Google’s weak Photos service does not currently support JPEG XL images. Mind you, nor does it support the display of AVIF files in HDR format either! Timescales on JPEG XL support in Chrome and Google Photos is anyone’s guess.
So, while JPEG XL offers compelling performance benefits, browser support is currently weak. However, I do not see this as a major short-term hurdle. Appropriate choice of platform, applications and devices will allow JPEG XL to be used extensively, while the AVIF image format (discussed next), can be used to share images as it has widespread browser support.
I have detailed my own Apple-centric workflow, with JPEG XL at its heart, here:
What is the Perfect True HDR Photography Workflow?
Figure 1: Workflow for True HDR Photography with Lossless JPEG XL at its Heart
I am able to use lossless JPEG XL extensively as my main HDR image format. However, for incorporation into websites, I currently use AVIF (discussed next).
There is a highly-attractive aspect of JPEG XL that does not currently receive widespread attention. Lossless JPEG XL has obvious appeal given that no information whatsoever is discarded i.e. it is truly, or mathematically, lossless. It is the most efficient lossless format available (offering the smallest file size). It is important to note that, while high levels of compression with lossy JPEG XL can degrade image quality noticeably (in return for dramatically smaller file size), more modest levels of compression can deliver outstanding image quality while reducing file sizes compared with truly lossless JPEG XL. JPEG XL can be “visually lossless” (i.e. appear the same as a lossless file to the naked eye) with moderate levels of compression.
Adobe Camera RAW allows you to select quality levels from 1 to 13 – with 13 defined as ‘Lossless’, 10-12 as “Very High Quality”, 8-9 as “High Quality”, 5-7 as “Medium Quality” and 1-4 as “Low Quality”. Figure 2, below, shows the file sizes resulting from selecting different quality level for an image with dimensions of 5000 x 3333 pixels. Selecting the truly lossless variant resulted in a file size of nearly 60 MB. However, by selecting “Very High Quality” levels it was possible to reduce file sizes appreciably, By eye, I was unable to see any noticeable image degradation with a quality of level of 11, which was, effectively, “visually lossless”. However, the file size (6MB) was about one-tenth the size of the truly lossless file. Many photographers are going to be happy not using truly lossless files in their workflows given that lossy JPEG XL is so effective in reducing sizes while maintaining outstanding image quality, provided that compression is not pushed too far. These “visually lossless” files would certainly be easier to store and share.
Figure 2: The Effect of Image Compression on the Size of JPEG XL Files
While the short-to-long-term role of JPEG XL in True HDR Photography workflows is secure, the format’s short-to-medium-term use for widespread sharing on the Internet is less certain. Given Google’s previous decision with Chrome, it is difficult to predict the speed at which browser support for JPEG XL will now improve. I expect Chrome support for JPEG XL in mid-2026. I hope that everyone will eventually standardise on one format (JPEG XL) for all purposes, but this transition may take many years. Google’s attempt to kill off JPEG XL clearly backfired. I welcome the leadership roles that Apple and Adobe have played with JPEG XL to support photographers and their focus on image quality, innovation and page loading speeds.
For more information about JPEG XL, visit:
The official Joint Photographic Experts Group (JPEG) committee website
JPEG White Paper: JPEG XL Image Coding System (Jan 2023)
“The Case for JPEG XL” by Jon Sneyers (Nov 2022)
“U-turn: Google wants to bring JPEG XL back to Chrome”, heise online (Nov 2025)
“Google snubbed JPEG XL so of course Apple now supports it in Safari”, The Register (Jun 2023)
AVIF is a great all-rounder with much better browser support than JPEG XL currently so has a valuable role to play
The AVIF (AV1 Image File Format) was developed by the Alliance for Open Media from the AV1 video codec. It is an open, royalty-free image format that was released in 2019. AVIF has become an image format that is widely supported in browsers, including Apple Safari and Google Chrome.
Being a relatively modern creation, compression algorithms are significantly superior to the conventional JPEG. Therefore, AVIF offers significantly smaller file sizes than JPEGs, making the format ideal for speeding up today’s websites. Typically, AVIF files are about 50% of the size of conventional JPEGs.
Importantly, AVIF also offers true HDR capability and supports wide colour gamuts.
AVIF is currently supported by browsers used by an estimated 93% of users worldwide. The use of AVIF images on websites has been gradually increasing, primarily as a means of speeding up performance. As images typically account for a large proportion of a typical webpage, in terms of size, AVIF images can improve web page downloading times considerably. My own portfolio of websites has been using (standard dynamic range) AVIF files for several years.
The AVIF format supports HDR. For example, this website delivers a combination of HDR and non-HDR AVIF images.
AVIF HDR images now have a broad range of browser support, including Apple Safari, Google Chrome, Firefox and Edge. This makes the AVIF HDR format the best choice for the display of HDR images on websites until browser support for JPEG XL improves.
For use on the Web, AVIF HDR files can include a Gain Map, which I strongly recommend. This allows non-HDR-compatible devices to construct a better standard dynamic range image than if left to automated tone mapping. Unlike Gain-Mapped JPEG (where the Gain Map is fundamentally built in to the format), Gain Maps have been rather an optional, add-on with the AVIF format. AVIF HDR images are now supported with or without Gain Maps in the latest versions of all major browsers.
In my own testing, I have found that AVIF HDR files with Gain Map can deliver substantially superior HDR images than Gain-Mapped JPEG with substantially smaller file sizes. I find that it is possible to replace a conventional JPG with an AVIF file (offering both HDR and SDR images), resulting in noticeably improved image quality and reduced file sizes.
There have been a number of studies comparing the performance of AVIF with JPEG XL. These suggest that AVIF’s strength is in producing very small (but lower quality) images. AVIF cannot match the image quality of JPEG XL when very high visual quality is required. JPEG XL’s strength lies in its ability to create the smallest lossless file possible while also producing (smaller) “visually-lossless” or “near-visually-lossless” image files. AVIF seems to particularly suit applications where very small file sizes are needed, albeit at the cost of image quality. Relatively low compression levels really help JPEG XL to deliver outstanding results, while some (modest) artifacts can still remain with AVIF at relatively low compression levels. Having said all this, AVIF is still an excellent image format, and so much better than Gain Mapped JPEG!
For further information, please visit:
The official Alliance of Open Media website
What is AVIF? (Alliance of Open Media)
Greg Benz “Which File Formats to Use for Photography” (Mar 2025)
The HEIF/HEIC formats have played an important role in Apple’s early HDR efforts but JPEG XL is set to play a more major role for Apple
The High Efficiency Image File Format was standardised in 2015, but has failed to see widespread adoption outside of Apple’s ecosystem. Apple was the first main adopter of the format (using the HEIC variant), in 2017, when it was incorporated into its iOS 11 operating system. HEIF/HEIC supports both SDR and HDR images, and can compress images to about half the size of a standard JPEG. It supports higher colour depths than 8 bits.
HEIC/HEIF are much better suited to True HDR Photography than Gain-Mapped JPEG because they support higher color bit depths and uses more efficient, modern compression.
The formats have never seen widespread adoption beyond Apple’s ecosystem. HEIC has been the default format used to save photos taken on Apple’s iPhone and its ability to support HDR images has allowed captured HDR photos to be directly displayed on the iPhone’s screen or sent via Apple Messaging to other iPhone users while still retaining HDR. To many, HEIF and HEIC are seen as Apple’s proprietary formats, even though they are not. As long as you remain in Apple’s ecosystem, HDR HEIC/HEIF do a much better job than Gain-Mapped JPEG in terms of HDR image quality and file sizes.
Apple still actively uses the HEIC/HEIF formats (for example, for its iPhone and its recently-launched HDR-enabled screen capture tool on macOS). Here is an example of a screen captured by Apple’s screen capture tool in HEIF format (and then converted to AVIF for website display).
Adobe Camera RAW reads HEIC/HEIF files, and so images can be converted easily to more widely compatible formats. It is not possible to export HEIC/HEIF from Camera RAW, however. It is possible to create HDR HEIC files from Apple’s Preview macOS application for any particular image you want to convert. After selecting “Export”, you can select HEIC and a depth of 10 bits per channel. You even have the choice of compression, including a lossless option.
It remains to be seen if Apple eventually replaces HEIC/HEIF with the JPEG XL format. I certainly hope so! Apple now uses the lossless JPEG XL format to store iPhone RAW files, so a transition to lossy JPEG XL could make sense. Personally, I don’t just want to use Apple Messaging to share HDR photos taken with my own iPhone and would also like to send edited HDR images from my other cameras to other iPhone users too. Apple’s past preference f0r HEIC/HEIF over Gain-Mapped JPEG shouldn’t limit opportunities with JPEG XL.
“HEIC vs. JPEG”, Adobe’s website
“JPEG vs HEIC: Which File Format is Right for You?”, Digital Photography School
HDR image formats are now stable enough to define future-proof true HDR photography workflows
The future is uncertain, and nothing is more frustrating than investing time and effort into using certain formats (e.g. processing images and adding them to websites) and then having to repeat the process again as things change. However, I feel that the future is becoming clear enough to define future-proofed workflows for the next few years.
Firstly, there is no long-term future in JPEGs with Gain Maps. It’s a hacked, interim format, which puts an artificial constraint on HDR image quality and file size improvements. I will not be wasting any of my own time with this format.
Secondly, I see no major expanding role for HEIC/HEIF HDR formats, despite them being much better than Gain-Mapped JPEG. I hope that Apple will continue to increase focus on the support for JPEG XL across its ecosystem, as I believe JPEG XL provides a highly attractive replacement to HEIC/HEIF.
JPEG XL is (already) a very compelling format, particularly as it offers a truly lossless option while maintaining outstanding image quality at relatively modest compression levels. The ability of various Apple products to use JPEG XL files (e.g. Apple Photos/iCloud, Final Cut Pro and Keynote) has allowed me to construct a workflow with the uncompressed JPEG XL format at its very heart. I am hoping that Apple’s support for the JPEG XL HDR format will be further cemented during 2026. Apple TV needs to be able to display JPEG XL files in HDR format and Apple Messages needs to be able to display JPEG XL files in HDR too. Improving Apple’s screen capture software in both iOS and macOS, so that images can be saved in JPEG XL HDR format would be very useful.
The lack of browser support for JPEG XL means that there is still an important role for AVIF in the coming years, which benefits from excellent browser support. Even if JPEG XL had widespread support, you would need to compress large lossless JPEG XL files into much smaller, lossy JPEG XL files to minimise page loading times. As a result, the addition of the AVIF format to the workflow (rather than using JPEG XL throughout) adds no increased effort. Also, given that AVIF can offer similar image quality to JPEG XL (with not dissimilar file sizes), there would be no strong need to change out AVIF website images, at least in the short to medium term. Having said this, JPEG XL does have its valuable progressive decoding feature, which aims to enhance user experience on slow connections by displaying parts of the image sooner than other formats before filling in the full image. Once there is widespread browser support for JPEG XL, I will migrate to JPEG XL images on my websites. With progressive decoding – which is particularly suited to mobile devices – initial page loading can be extremely quick while a very-high-quality image can be progressively loaded.
Other pages you may be interested in:
What is the Perfect True HDR Photography Workflow?
La Sagrada Familia in Barcelona – a showcase of True HDR Photography