Filmic to linear math? I know the math to convert sRGB and REC709 to linear, but does anyone know what is the (approximative?) math for filmic to linear?

Or is there a way to use OCIO configs in python to convert any picked color to be converted to linear, independently of the color profile you are using?

Thanks!
You can use the OpenColorIO Python library to transform a Filmic log encoded image back to scene referred linear.

The base log is a simple normalized log base 2 format, with ten stops down from middle grey and six and a half stops up.