OpenEXR is a low-res raster graphics format developed by ILM for use in the computer-image and visual effects industries, both computer animations and visual effects. Its multiple-resolution and fixed-arity pixel format makes it attractive for compositing, since it eliminates a number of painful elements of this process. In particular, the OpenEXR raster draw on memory at a higher rate than its predecessor, GIF. It's possible to store about five megabytes worth of information on just one gigabyte of RAM using OpenEXR. Its raster feature also allows the user to work with rasters in the horizontal and vertical direction, which is useful for animating complex 3D scenes.
The openEXR software was first released in October, 1995, shortly after the specification of the GIF, which was itself a culmination of many years' worth of work. At this point, however, it had no competition, since GIF was owned by the established vendor Necci. Necci released its own version of the format, called GIF, and this became the standard format for animated web pages and images. At the time, OpenEXR looked like a promising competitor to GIF but was hindered by the fact that it was new and didn't have a wide adoption by browsers. This meant that it would have to spend more time developmentally testing its visual compression algorithms, which it did not have enough time to do.
On July 10th, 1996, a new version of OpenEXR was released, with additional features that made it different from GIF. Among these features were support for a wide range of raster formats (the ones that OpenEXR itself was based on), a new "compression style" algorithm that removes extraneous data from the compression process, and a new visualization tool called ZBrush. With the additional features of the new release, OpenEXR v2 has become the most popular compression format for both web and images. It is capable of decompressing rates in double-speed, compression of JPEG files with an edge-wise or center-aligned algorithm, and compression of several common graphics formats using a technique called "packed compression." OpenEXR v2 can also decompress audio files in real time, as well as decompressing rates in 16-bit float mode.