dir_transversible_permissions
makethumbs goes to great lengths to operate correctly despite highly restrictive umask settings. It chmod's all of its created files and the current working directory so that the files/dir can be read by the web server.
You may not want makethumbs changing your
permissions on you (cf change_file_permissions
),
or you may want to tweak the exact permissions it sets. Both are
possible.
This variable has a permission specification to chmod.