This is on the master branch only (development version). You can build it yourself, or get one of the snapshot builds. What OS are you on? (Linux, Windows, OSX?)
There are 2 new tools available
- exposure matching and
- colour matching.
I’ve already linked the one for colour matching; that has a link to the one for exposure matching, too.
As Soupy said, maybe for now you could use colorize? Or perhaps color mapping?