Exrtools is a set of simple command-line utilities for manipulating with high dynamic range images in openexr format. openexr is a high dynamic-range (hdr) image file format developed by industrial light & magic for use in computer imaging applications.

exrtools was developed to help experiment with batch processing of hdr images for tone mapping. each application is small and reasonably self-contained such that the source code may be of most value to others.

you can find more information at http://scanline.ca/exrtools/