HDR to AVIF Converter
Convert HDR to AVIF in your browser. HDR files usually come from HDRI environment maps, 360° panoramas and lighting simulation; AVIF is the better fit for maximum compression on modern websites. You get an AVIF encoded with libavif (AV1) compiled to WebAssembly, at the quality you choose. Nothing is uploaded.
- Processed locally
- No upload, no wait
- No sign-up
- No watermark
Drop images here
or choose files · paste with Ctrl/⌘ V
HDR expected · other image formats also work
How to use HDR to AVIF
- 1
Add your HDR files: drop them here, choose them, or paste from the clipboard.
- 2
Set the quality. AVIF quality numbers run lower than JPEG: around 55 to 65 already looks excellent. Encoding is slow on phones.
- 3
Click Convert. Each file is decoded and encoded in a background thread on this device.
- 4
Download the .avif files one at a time or together as a ZIP.
Why use Aback Images for hdr to avif
Where the AVIF goes next
AVIF opens in Chrome, Edge, Firefox, Safari 16 and later, Windows 11 Photos, macOS Preview and recent editors.
AVIF next to HDR
A lossy AVIF usually comes out far smaller than the HDR, which stores run-length encoded RGBE scanlines.
The first lossy pass
The HDR holds an 8-bit mantissa per channel sharing an 8-bit exponent (RGBE), 32 bits per pixel with nothing discarded yet. This conversion is the first lossy encode these pixels see, and hard edges and flat colour show it first.
Processed on your device
Your images are decoded, edited and encoded inside this browser tab by Web Workers. Nothing is uploaded to a server.
HDR vs AVIF
What changes from HDR to AVIF
Encoding: the HDR uses run-length encoded RGBE scanlines; AVIF uses lossy or lossless AV1 intra-frame coding, and the download is an AVIF encoded with libavif (AV1) compiled to WebAssembly, at the quality you choose.
Bit depth: an 8-bit mantissa per channel sharing an 8-bit exponent (RGBE), 32 bits per pixel in the HDR; AVIF allows 8, 10 or 12 bits per channel, and the AVIF written here has 8 bits per channel. The high dynamic range is mapped to 8 bits per channel, and values above white clip.
Colour: linear RGB (or XYZ in the XYZE variant) in the HDR; AVIF supports YUV 4:4:4 or 4:2:0 with BT.709, Display P3 or BT.2020 primaries, HDR curves possible, written here as 8-bit sRGB.
Metadata: the HDR can carry a text header with FORMAT, EXPOSURE and optional comments; AVIF can carry EXIF, XMP and ICC stored as HEIF items, but nothing is copied across.
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.
HDR files usually come from HDRI environment maps, 360° panoramas and lighting simulation.
About AVIF
AVIF uses the AV1 video codec for still images. It is the most efficient widely supported format, often half the size of JPEG, with HDR, wide colour and transparency, but encoding is slow.
An AVIF is a HEIF file, the same ISO base media boxes as MP4, with the brand 'avif'. The picture is an AV1 key frame stored as an image item, and its size, colour and pixel layout are item properties.
When converting HDR to AVIF makes sense
AVIF is the better choice for maximum compression on modern websites, while HDR suits 3D lighting and environment maps.
AVIF strengths: Often 50% smaller than JPEG; Excellent at low quality settings; Transparency, HDR and 10/12-bit colour. Drawbacks to weigh: Slow to encode, especially on phones; Not supported by some older software; Can smooth away fine texture at low quality.
Limitations
- Light values above 1.0 are clipped rather than tone-mapped, so the sun and bright sky turn flat white.
- Environment maps are 2:1 equirectangular panoramas, so the picture looks stretched near the top and bottom, as it should.
- Files in the XYZE variant cannot be read here; RGBE files, the common kind, can.
- AVIF encoding is CPU-heavy, so large images and big batches take noticeably longer than JPG or WebP, especially on phones.
- Some older apps and operating systems cannot open AVIF yet; keep a JPG copy if you share the file widely.
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Frequently asked questions
Does converting HDR to AVIF lose quality?
AVIF is lossy, so detail the eye barely notices is discarded to save space. The high dynamic range is mapped to 8 bits per channel, and values above white clip.
What quality should I choose for AVIF?
AVIF quality numbers run lower than JPEG: around 55 to 65 already looks excellent. Lower values give much smaller files with gentle softening. Encoding is CPU-heavy, so large batches take a while on phones.
Which apps open AVIF files?
Chrome, Edge, Firefox, Safari 16 and later, Windows 11 Photos, macOS Preview and recent editors. It opens in Chrome 85+, Edge, Firefox 93+ and Safari 16+.
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.