Dear Junha Song, You can use "vop scale" with a negative factor value: <https://www.rbvi.ucsf.edu/chimera/docs/UsersGuide/midas/vop.html#scale> For example: vop scale #2 factor -1 Also, if you're interested in switching to ChimeraX, it has the same function as "volume scale": <https://rbvi.ucsf.edu/chimerax/docs/user/commands/volume.html#scale> I hope this helps, Elaine ----- Elaine C. Meng, Ph.D. UCSF Chimera(X) team Department of Pharmaceutical Chemistry University of California, San Francisco

On Oct 31, 2022, at 10:42 AM, Junha Song BA via Chimera-users <chimera-users@cgl.ucsf.edu> wrote:

Dear RBVI,

I am currently looking into the ways to invert a map in UCSF Chimera so that I can flip the histogram of a map, but I cannot find a volume operation command that does the job. What command in UCSF Chimera allows creating a map with inverted map values? I thought it was vop but I cannot find a parameter that allows assigning negative value operation that would invert the map in UCSF Chimera command line documentation.

Best, Junha Song.