OpenEXR is visual effects industry-standard floating point file format
and the best format to use when working with 32-bit HDR imagery in
Photoshop and After Effects.
However, Adobe's support for the format is minimal - only with ProEXR
can digital artists finally access all the power available in OpenEXR.
OpenEXR can support multiple layers of imagery, but Photoshop can't
read or save layered EXR files...unless you have ProEXR.
Store all your layers in file and read them into After Effects, Nuke,
Shake, and Fusion. Or in step save layers as individual files for
programs that are less EXR savvy.
ProEXR will also read all the image buffers created by modern 3D
renderers and place each in its own Photoshop layer.
ProEXR lets you choose from all the compression options available in
Most EXR compression is lossless, but of the most interesting
options is a lossy method similar to JPEG, applied to the world of
Using B44 compression and Luminance/Chroma sampling, HDR
images can be crushed to a fraction of their uncompressed size,
usually without visible artifacts, only in ProEXR.
Other ProEXR features include:
* Retention of EXR color space information.
* Support for both 32-bit and 16-bit floating point.
* Full control over alpha channel processing.
* Automatic EXR project set-up in After Effects.
* Built with the latest OpenEXR libraries.
* Free, open source After Effects plug-ins for working
with OpenEXR files and 3D Channels.
Copypasta from: http://forum.cgpersia.com/f14/fnord-proexr-v1-5-photoshop-after-effects-cs3-cs5-21144/#ixzz2K68cBcY9