JXL to HDR Converter
Convert JXL to HDR in your browser. JXL files usually come from image editors, archival pipelines and lossless JPEG recompression; HDR is the better fit for 3D lighting and environment maps. You get a Radiance RGBE (.hdr) file, with the 8-bit sRGB values converted to linear light. Nothing is uploaded.
- Processed locally
- No upload, no wait
- No sign-up
- No watermark
Drop images here
or choose files · paste with Ctrl/⌘ V
JXL expected · other image formats also work
How to use JXL to HDR
- 1
Add your JXL files: drop them here, choose them, or paste from the clipboard.
- 2
Pick the colour that replaces transparent areas, since HDR has none.
- 3
Click Convert. Each file is decoded and encoded in a background thread on this device.
- 4
Download the .hdr files one at a time or together as a ZIP.
Why use Aback Images for jxl to hdr
Where the HDR goes next
HDR opens in Blender, Photoshop, Houdini, Unreal Engine, Unity and Affinity Photo.
HDR next to JXL
The HDR keeps the decoded pixels without lossy compression, so expect it to be larger than the JXL.
No new artefacts
JXL is already lossy, since it stores lossy VarDCT or lossless modular coding; existing JPEGs can be repacked without loss; the HDR keeps the decoded pixels losslessly, so this step adds no compression damage of its own.
Processed on your device
Your images are decoded, edited and encoded inside this browser tab by Web Workers. Nothing is uploaded to a server.
JXL vs HDR
What changes from JXL to HDR
Encoding: the JXL uses lossy VarDCT or lossless modular coding; existing JPEGs can be repacked without loss; HDR uses run-length encoded RGBE scanlines, and the download is a Radiance RGBE (.hdr) file, with the 8-bit sRGB values converted to linear light.
Bit depth: 8 to 16 bits per channel, or floating point in the JXL; HDR allows an 8-bit mantissa per channel sharing an 8-bit exponent (RGBE), 32 bits per pixel, and the HDR written here has RGBE, 32 bits per pixel. High-bit-depth JPEG XL files are reduced to 8 bits per channel.
Colour: sRGB, Display P3, linear and other spaces described in the codestream in the JXL; HDR supports linear RGB (or XYZ in the XYZE variant), written here as linear-light RGB.
Transparency: the JXL stores it as an extra channel in the codestream; the HDR has none, so transparent areas are filled with the colour you choose.
Animation: frames inside a single codestream; the HDR holds one image, so only the first frame is converted.
Metadata: the JXL can carry EXIF and XMP boxes in the container form, often stripped by encoders; HDR can carry a text header with FORMAT, EXPOSURE and optional comments, but nothing is copied across.
About JXL
JPEG XL is a next-generation format designed to replace JPEG. It compresses better than JPEG and WebP, supports lossless, HDR and progressive decoding, and can losslessly repack existing JPEGs.
A JPEG XL file is either a bare codestream starting with FF 0A or an ISO base media container whose 'jxlc' box holds the codestream. A recompressed JPEG keeps a 'jbrd' box that lets the original JPEG bytes be rebuilt exactly.
JXL files usually come from image editors, archival pipelines and lossless JPEG recompression.
About HDR
Radiance .hdr stores high dynamic range light values, widely used for 3D environment maps and HDRI lighting.
A Radiance file starts with '#?RADIANCE' (or '#?RGBE'), text lines such as FORMAT=32-bit_rle_rgbe and EXPOSURE, a blank line, a resolution line like '-Y 2048 +X 4096', then the scanlines.
When converting JXL to HDR makes sense
HDR is the better choice for 3D lighting and environment maps, while JXL suits archiving and future-proof high quality storage.
HDR strengths: True high dynamic range; Standard for HDRI environment maps. Drawbacks to weigh: Needs tone mapping to view on normal screens.
Limitations
- No range is added: the HDR holds the 8-bit picture in linear light, and nothing in it is brighter than the original white.
- 3D software treats the file as linear light, so an ordinary photo used as an environment map may need its exposure raised to light a scene well.
More conversions
Related tools
Convert HDR to JXL in your browser, ready for archiving and future-proof high quality storage. Batch, private, no uploads.
Convert JXL to JPG in your browser, with transparency filled in a colour you pick. Batch, private, no uploads.
Shrink JPG, PNG, WebP, AVIF and GIF files with MozJPEG, OxiPNG and modern codecs, with a live before/after preview.
Resize to exact pixels, a percentage or a longest side, with Lanczos3 and Magic Kernel resampling. Batch ready.
Strip EXIF, GPS, XMP, IPTC and comments losslessly. Pixels are never re-encoded for JPG, PNG and WebP.
Convert between 34 image formats in bulk: HEIC, WebP, AVIF, JPEG XL, PNG, JPG, GIF, TIFF, SVG, ICO, PSD, RAW and more.
Frequently asked questions
Does converting JXL to HDR lose quality?
HDR is written losslessly, so the pixels are stored exactly as decoded. Artefacts already in the JXL stay, but nothing new is lost. High-bit-depth JPEG XL files are reduced to 8 bits per channel.
What happens to transparency when converting JXL to HDR?
JXL stores transparency as an extra channel in the codestream. HDR has no alpha channel, so transparent pixels are composited onto a solid colour, white unless you pick another. To keep transparency, convert to PNG, WebP or AVIF instead.
Will my animated JXL stay animated?
No. HDR holds a single image, so only the first frame is kept. Convert to animated WebP, APNG or GIF to keep the motion, or export every frame with the GIF Frame Extractor.
Does saving as HDR make a real HDRI?
No. A real HDRI is merged from several exposures. This file holds an 8-bit image in linear light, so 3D software reads it correctly, but it has no more range than the source.
Which apps open HDR files?
Blender, Photoshop, Houdini, Unreal Engine, Unity and Affinity Photo. It does not open in web browsers.
Are my images uploaded anywhere?
No. Processing happens inside your browser with WebAssembly and Web Workers. The site only downloads the app code and codecs; your files never leave your device. You can confirm this with the live upload counter on the tool, or in your browser's network panel.
Can I process many files at once?
Yes. Drop a whole selection or folder. Files are processed in parallel on several worker threads, each result can be downloaded on its own, and everything can be saved as one ZIP.
Is it free? Is there a file limit or watermark?
It is free with no account, no watermark and no daily limit. The only limit is your device's memory: very large images (over roughly 100 megapixels) may be refused to keep the tab from crashing.