OpenEXR

OpenEXR (also known as EXR or IlmImf) is a raster image file format developed by Industrial Light & Magic. It supports high dynamic range images. It usually uses 16-bit "half precision" floating point samples, though other sample formats are also supported.

Identification
Files start with bytes.

Specifications
The written documentation is unofficial. The format is defined as "whatever the IlmImf Library reads and writes."
 * Technical Introduction to OpenEXR
 * OpenEXR File Layout

Software

 * The IlmImf Library, a.k.a. The OpenEXR source distribution (C++): OpenEXR Downloads → openexr-x.x.x.tar.gz, ilmbase-x.x.x.tar.gz
 * abydos

Sample files

 * https://telparia.com/fileFormatSamples/image/exr/
 * The IlmImf Library includes some samples files for testing.

Links

 * OpenEXR home page
 * Wikipedia article