Grey scale false color from HDR

The Falsecolor (not Honeybee_FalseColor) component only has a select number of color pallets. I have an input HDR file and I want to create a false color image of this but in grey scale.

Thanks!

I doubt if you can do this directly with Honeybee, but this solution that Axel Jacobs suggested 8 years ago will still work as the source code of Falsecolor hasnt changed much.

Regards,
Sarith