Hello,
I think for greyscale, the RBG colors are all equal, and vary between 0 and 255. That is, 0,0,0 corresponds to black and 255, 255, 255 correponds to black... where 127, 127, 127 would be some intermediate shade of grey. You can use RGB to Color.vi to build an array of colors which correspond to these greyscale colors to use for your color table input. Attached is a screenshot of the code which you can build very quickly in your version of LabVIEW!
Best Regards,
JLS