Invariant command

[skylerpaulus]

Hello, I was following along to the Robotics, Vision and Control Fundamental Algorithms in MATLAB second edition book, chapter 10.4.2 in shadow removal.

Using the command invariant(im, 0.7, 'noexp'); in MATLAB I get unrecognized function.
After looking into both MVTB and RTB I cannot find this function anywhere. I searched online as well but had no luck. I was hoping by posting here someone might be able to help me recover this function.

esttheta also does not show up in either toolbox

Thanks