Sample Files
Details
HDR
High Dynamic Range
About
What is .HDR?
HDR (Radiance High Dynamic Range) is an image format used to store high-precision lighting information. Unlike standard image formats, `.hdr` files can represent very bright and very dark areas accurately, making them ideal for image-based lighting, rendering, and visual effects.
History
Origin of HDR
The image format, commonly known as the Radiance HDR format, was introduced as part of the Radiance lighting-simulation system developed at Lawrence Berkeley National Laboratory in the 1980s. The Radiance format was designed to store high dynamic range image data, representing real-world lighting intensities with far greater precision than standard low-dynamic-range (LDR) formats. It uses an efficient RGBE encoding method that compresses floating-point pixel data. HDR became widely used in computer graphics, visual effects, and lighting workflows, and influenced the development of later HDR formats such as OpenEXR.
Learn more at: https://radsite.lbl.gov/radiance/
Benefits
Stores high dynamic range lighting information using floating-point precision
Efficient RGBE encoding reduces file size while maintaining accuracy
Ideal for environment maps, skyboxes, and photorealistic rendering
Widely supported in 3D software, game engines, and rendering pipelines
Easy to process and convert compared to more complex HDR formats
Usage
Open `.hdr` files in tools like Photoshop, Blender, GIMP (with plugins), or HDR-specific software
Use `.hdr` images for environment lighting in 3D engines such as Unity, Unreal Engine, or Blender Cycles
Convert `.hdr` files to EXR, PNG, JPG, or TIFF depending on workflow needs
Apply tone mapping to generate standard LDR preview images
Use Cases
Common Use Cases
Here are the use cases for this file extension
Image-Based Lighting (IBL)
Used in 3D rendering engines to simulate realistic lighting using environment maps.
Visual Effects & CGI
VFX pipelines use HDR files for accurate reflections, shadows, and global illumination.
Photography & HDR Merging
HDR photographs merged from multiple exposures can be exported to `.hdr` for tone mapping.
Compatibility
Supported By
This extension is compatible with the following platforms.
Windows (HDR editors & 3D tools)
macOS (graphics & VFX tools)
Linux (open-source imaging and rendering software)
Android (via HDR-capable image viewers)
iOS (specialized apps, limited native support)
Game Engines (Unity, Unreal)
More Details
Technical Specs
Here are some technical details about this extension
File Extension
.hdr
MIME Type
image/vnd.radiance
Container Format
Radiance RGBE (floating-point encoded)
Color Encoding
RGBE (Red, Green, Blue + Exponent) high-dynamic-range format
Bit Depth
32-bit per pixel (8-bit RGB + shared 8-bit exponent)
Metadata Support
Yes (exposure, camera info, software comments)
Typical Use
Lighting reference images, environment maps, HDR rendering
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Got Questions?
Get answers to common questions
Radiance HDR uses simpler RGBE encoding, while OpenEXR supports multiple channels, deep data, and 16/32-bit floating-point precision for professional VFX pipelines.
Most monitors display files using tone mapping, since Radiance HDR stores true lighting values far beyond standard display brightness.
HDR stores real lighting intensities, allowing 3D renderers to produce realistic reflections, specular highlights, and global illumination.