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Does JPEG Support HDR?
3 min read · September 20, 2026 · Mochify Engineering Team
Yes. A JPEG can carry HDR through a gain map: a small second image stored inside the same file that tells an HDR display how much brighter each region may go than the normal picture. Google calls the result Ultra HDR, Apple calls it Adaptive HDR, and since July 2025 the mechanism is an international standard, ISO 21496-1. The file is still an ordinary JPEG, so it opens in every app and browser; only screens and software that understand the map show the extra brightness, and everything else shows the standard photo underneath.
Quick answer
Yes. A JPEG can carry HDR as a gain map (Ultra HDR / Adaptive HDR, ISO 21496-1): it opens everywhere as a normal photo and shows extra brightness on HDR screens.
How a JPEG carries HDR
An Ultra HDR JPEG is two pictures in one container. The base image is a normal 8-bit JPEG. Appended to it is the gain map, a grayscale ratio image that Android's specification recommends storing at a quarter of the width and height, so one sixteenth of the pixels, compressed like any other JPEG (Android Ultra HDR image format). On Mochify's pipeline the map typically adds a low single-digit percentage to the file size. A viewer that reads the map multiplies the base image by it and pushes highlights past white; a viewer that does not simply ignores the extra data. Recent Pixels capture Ultra HDR by default, and Apple's engineers confirmed at WWDC 2024 that JPEG "fully supports" its Adaptive HDR gain maps alongside HEIF.
The trap: "JPG to HDR converter" usually means a different HDR
Search "convert JPG to HDR" and most of the tools that rank will give you an .hdr file, not an HDR JPEG. That extension belongs to Radiance RGBE, a 1980s format used for lighting 3D scenes in Blender and Maya, and the converter sites say so in their own copy (ChangeMyFile's page describes its output as "environment maps for 3D lighting"). Your phone cannot open it, Instagram will not accept it, and it adds no brightness to anything. The tell is the output: if the result is .hdr, .pic or .exr, you have the wrong HDR. If it is a .jpg that mentions a gain map or Ultra HDR, you have the right one; our guide to making any photo Ultra HDR lists the tools that produce one on each platform. A third thing sold as HDR, the "HDR filter" in photo apps, is a look applied to an ordinary image and displays identically on every screen.
What about JPEG XL, AVIF, WebP and PNG?
They handle HDR differently or not at all. AVIF and JPEG XL can store HDR in the pixels themselves, with no standard-range fallback image, so they look right only where the viewer decodes HDR. WebP and PNG cannot carry HDR in common use. That is why Mochify's converter returns a gain map only on JPG output: ask for AVIF, JXL, WebP or PNG and you get a standard-range file, because none of those can carry an Ultra HDR map on this path.
Want to make one?
Mochify's SDR to HDR converter turns any photo into an Ultra HDR JPEG, keeping a gain map that is already there and generating a modest one, about 1.5 stops, when there is none. It also shows the same photo as SDR and Ultra HDR side by side, which tells you in one glance whether your screen displays HDR at all. It works the other way too: run an Ultra HDR file through as JPG without asking for HDR and the map is dropped, so you get a plain standard-range JPEG back.