Right, here you go. Had issues getting gamma to work, no idea what parameter settings I need.
Instead I used the AdjustHSL-effect and ramped that up from a default value of 100
[attachment=0:126ffluv][/attachment:126ffluv]
Not sure I'm completely satisfied the way the colors shift to white, but it's working at least
It seems the effect has issues with areas where alpha is at full opacity or tranparency.