Question posted in 
I currently have a script which processes .exr files, and when manually opening an exr file you are given the option of opening with transparency or with alpha. However, when scripting the opening of an .exr you are given no such options. There is no OpenOptions like there is for say PDF, and as far as I can tell their is no code generated by the listener that dictates the choice between transparency or alpha. Additionally this choice does not seem to be captured via an open action.
My question is: Has anyone figured out a way in CS6 or in CC a way to choose automatically whether an .exr file loaded through scripting is loaded with alpha or transparency?
2
Answers
Answering my own question.
As far as I can tell there is no way to script any behavior relating to opening EXR files with alpha/transparency. The way I was able to work around this was using the Pro EXR plugin, specifically the EZ version which is free, to automatically set exr files to always open with alpha. It's very disappointing that even in CC exr files lack any sort of script-able options when opened. Hopefully adobe will fix this is future versions.
Link to the plugin. The installer zip includes the free version. You can bring up the default options if you press shit when opening a file. I hope this helps someone else who may find themselves needing to interact with exr files with photoshop scripting.
For anyone who stumbles upon this, here’s a little history on the subject of Photoshop EXR format implementation (specifically about this alpha split issue):
https://forums.adobe.com/thread/369637
The gist of it is that Adobe developers work with “straight alpha” which means transparency is a property of the alpha channel. The majority of visual effects software developers use an “unpremultiplied” alpha workflow, in which the alpha can represent anything, though crucially this is often used to represent objects that have transparency and brightness such as a candle flame.
An update on the answer from the asker – ProEXR is now open source, and there is an additional open source alternative called EXR-IO. Both work very well, and currently have slightly different feature sets.