rgb2dklCart not working?

Hi all,
I’m trying to convert RGB images into DKL space using rgb2dklCart(). However, passing in a numpy array representing a color image I’m returned with the equivalent array. It doesn’t appear the function is doing any conversion. Do others have issues with this function? Or am I misunderstanding something about the conversion? Thanks in advance!

Cheers,
Alex

Or rather, would someone provide some better documentation of the function? What do the values of each axis represent? How does the conversion relate to the spherical coordinates of the posted diagram?