Try this:
wget -nd -r -P /save/location -A jpeg,jpg,bmp,gif,png http://www.somedomain.com
Here is some more information:
-nd
prevents the creation of a directory hierarchy (i.e. no directories).
-r
enables recursive retrieval. See Recursive Download for more information.
-P
sets the directory prefix where all files and directories are saved to.
-A
sets a whitelist for retrieving only certain file types. Strings and patterns are accepted, and both can be used in a comma separated list (as seen above). See Types of Files for more information.