About EXR Files
OpenEXR Image
OpenEXR is a high dynamic range imaging format used in visual effects and film production.
Family
Raster & Vector Images
Extension
.exr
MIME Type
image/x-exr
Can Use As
HOW EXR
CAME TO BE.
OpenEXR was developed internally at Industrial Light & Magic starting in 1999 and released as open source in 2003 alongside the VFX work on the Harry Potter films. The format was built to solve a problem that had no good answer: how do you store a pixel with genuinely unbounded brightness? Film negatives and real-world light have no fixed ceiling — a 16-bit integer simply couldn’t represent a sunlit cloud next to a dark corner.
EXR’s answer was 16-bit and 32-bit floating point per channel, half-float values that could represent from 6×10⁻⁸ to 65 504 and full-float values that went essentially infinite. Paired with Wavelet and PIZ compression schemes, EXR became the backbone of every major VFX and 3D rendering pipeline: Disney, Pixar, Weta, DreamWorks, ILM. It even won an Academy Sci-Tech Award in 2007. If you’ve seen a modern CGI film, you’ve watched thousands of EXRs.
CURIOSITIES &
TRIVIA.
OpenEXR won the 2007 Academy Sci-Tech Award for Scientific and Technical Achievement — the Oscar for codecs.
Every frame of The Lord of the Rings: Return of the King post-production pipeline was an EXR.
A single EXR can carry dozens of "channels" — RGB, alpha, depth, motion vectors, normals, albedo, specular — all as first-class citizens.
EXR supports "deep" variants that store multiple samples per pixel for transparent-object compositing — a feature unique to the format.
A 4K half-float EXR with typical VFX channels can easily exceed 300 MB — one frame.
STRENGTHS &
LIMITATIONS.
Strengths
- Genuine high-dynamic-range storage (32-bit float per channel).
- Multi-channel layers native — store an entire render pass in one file.
- Industry standard across every major VFX and animation studio.
- Deep samples enable modern compositing workflows.
- Open-source reference implementation with mature tooling.
Limitations
- Enormous file sizes.
- Not a web format — browsers don't display EXR.
- Decoding is CPU-intensive.
- Consumer apps rarely need HDR at this precision.
Typical Sizes & Weights
1080p half-float with alpha
15-25 MB
4K multichannel VFX render
200-500 MB
8K deep EXR (heavy comp)
1-4 GB per frame
Technical Specifications
- MIME type
- image/x-exr
- Extension
- .exr
- Bit depths
- 16-bit half-float, 32-bit float, 32-bit uint
- Compression
- ZIP, PIZ, PXR24, B44, DWAA, DWAB, RLE, None
- Max channels
- Practically unlimited (arbitrary named layers)
CONVERT FROM
EXR
Common Use Cases
VFX, HDR photography, film
Related Formats
Popular comparisons
EXR vs JPG
Differences, file size, and when to choose each format.
EXR vs PNG
Differences, file size, and when to choose each format.
EXR vs WEBP
Differences, file size, and when to choose each format.
EXR vs AVIF
Differences, file size, and when to choose each format.
EXR vs GIF
Differences, file size, and when to choose each format.
EXR vs BMP
Differences, file size, and when to choose each format.
Popular EXR conversions
The most-requested destinations when starting from EXR.
Frequently Asked Questions about EXR
Frequently Asked Questions
EXR (OpenEXR Image) is an image format used to store raster graphics — a two-dimensional grid of pixels describing a picture. It is part of the raster & vector images family and designed around a specific trade-off between file size, visual fidelity, and feature support (transparency, colour depth, compression type). Photographers, web designers, and content creators choose EXR when its particular strengths match the publishing target.
Most desktop photo viewers (Windows Photos, macOS Preview, GIMP, Photoshop, Affinity Photo) open EXR natively. On mobile, iOS Photos and Google Photos display EXR in the gallery when supported by the OS. If the format is rare or new, convert to JPG or PNG first — both are universally readable — using our EXR to JPG or EXR to PNG converter.
Upload the EXR to KaijuConverter and pick a target format (JPG, PNG, WebP, HEIC, TIFF, BMP, SVG, PDF). The conversion runs in the browser via ImageMagick and returns a download in seconds. No account or installation required; both input and output delete automatically within two hours.
It depends on the task. JPG is the smallest file size for photographs; PNG is lossless with transparency; EXR has its own niche that may favour colour depth, animation, or encoding efficiency over one or both of those. For the final web publish, test all three and measure file size plus visible quality on real content.