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


Details:

png file /svs/share/houdini/cbars/images/png/CET-L19.png
tex file /svs/share/houdini/cbars/images/tex/CET-L19.tex
definition /svs/share/houdini/cbars/definitions/CET_linear/CET-L19.csv
credit Peter Kovesi. Good Colour Maps: How to Design Them. arXiv:1509.03700 [cs.GR] 2015
reference https://colorcet.com/