Use filmic and output mask with absolute color values I would like to output both images where the color management (like filmic) is applied and save an object-ID pass. The catch is, the object-ID pass needs to contain the object as absolute white #FFFFFF. This of course doesn't work since the color management is set globally for the project and the "File Output"-node always applies the color management.

Is there any way to circumvent this? Since performance is critical I can't do a second render with switched color management.
Ok I found a way to do it. Instead of doing an alpha over with the ID Mask between black and white, I use black and a value node. The value node is set to a high value, high enough for the filmic color space transformation to map it to the maximum value 255/#FFFFFF in the output.

This has two problems though, 1) it depends on the "alpha over"-node to accept higher values than usually available (this should be ok, since internal representation is floating point), 2) I just took some high value instead of basing it on what value is mapped to white.