image-dired-cmd-pngnq-program

image-dired-cmd-pngnq-program is a variable defined in `image-dired.el'.
Its value is

nil

• This variable may be risky if used as a file-local variable.

Documentation:
The file name of the `pngnq' program.
It quantizes colors of PNG images down to 256 colors.

You can customize this variable.