Using the free plugin VC Color Vibrance
You can easily exclude the black background.
How to do it: Just apply VC Color Vibrance and make the Matte Alpha tab "Only".
* You can get the same effect as the plug-in "Unmult" whose free distribution has ended.
[VC Color Vibrance]
https://www.videocopilot.net/tutorials/color_vibrance_plug-in/