HolmesFTP is a small FTP client that can retrieve images. Its main feature for this purpose is that it can be configured not to download files that are already in the target directory.

usage is -u/-d -o/-s server username password "localdir" "remotedir" "filename"
-u for upload to server, -d for download from server
-o to overwrite existing files, -s to skip copying existing files

localdir\file must be in inverted commas filename is used for local or remote file, depending on upload or download use * for wildcards

The license of this software is Freeware, you can free download and free use this ftp software.