gnus-article-x-face-command

gnus-article-x-face-command is a variable defined in `gnus-art.el'.
Its value is

"{ echo '/* Format_version=1, Width=48, Height=48, Depth=1, Valid_bits_per_item=16 */'; uncompface; } | icontopbm | display -"

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

Documentation:
*String or function to be executed to display an X-Face header.
If it is a string, the command will be executed in a sub-shell
asynchronously. The compressed face will be piped to this command.

You can customize this variable.

This variable was introduced, or its default value was changed, in version 21.1 of Emacs.