In the Houdini colorbar HDA under "color options", set the menus like this...


Details:

png file /svs/share/houdini/cbars/images/png/NEO_div_vegetation_b.png
tex file /svs/share/houdini/cbars/images/tex/NEO_div_vegetation_b.tex
definition /svs/share/houdini/cbars/definitions/GISS_panopoly/NEO_div_vegetation_b.act
credit
reference https://www.giss.nasa.gov/tools/panoply/colorbars/