ILM Base libraries have following four libraries.

*Half is a class that encapsulates ILM's 16-bit floating-point format.

*IlmThread is a thread abstraction library for use with OpenEXR
 and other software packages.

*Imath implements 2D and 3D vectors, 3x3 and 4x4 matrices, quaternions
 and other useful 2D and 3D math functions.

*Iex is an exception-handling library.

WWW:	http://www.openexr.com/