Refine image source extraction unit tests
Refine image source extraction unit tests

git-svn-id: 71bcaaf8fac6301ed959c5094abb905057e55e2d@2875 2b73c8c1-3922-0410-90dd-bc0a5c6f2ac6

bartscheers/tkp,transientskp/tkp,bartscheers/tkp,transientskp/tkp,mkuiack/tkp,mkuiack/tkp