HDR (Radiance)
Also known as: Radiance HDR, .hdr file, RGBE format
HDR (Radiance) is a high-dynamic-range image format using the .hdr extension and an RGBE encoding that packs a shared exponent with red, green, and blue. It is widely used for lighting and environment maps in 3D rendering.
- High-dynamic-range image using RGBE encoding
- Common for 3D lighting and environment maps
- Not the same as a phone camera HDR photo
How Radiance HDR works
Instead of 8 bits per channel, the RGBE scheme adds a shared exponent byte so one file can represent very bright and very dim values at once. That makes it ideal for capturing real-world light levels.
In 3D software, .hdr files are commonly used as environment maps that light a scene and provide realistic reflections, often as 360-degree panoramas.
HDR (Radiance) vs HDR photos
Despite the name, this is not the HDR mode on a phone camera. A Radiance .hdr is a true floating-point light file for rendering, while a phone HDR photo is a normal merged JPEG or HEIC.