2009 LT finding source of oil leak/seepage under engine

[Drake314]

While doing an oil change on my 09 Aveo LT a few days ago I noticed that there is an oil leak/seepage underneath the engine specially under the oil pan and under the oil filter area, pictures are below. So far there is no dripping of oil onto the ground underneath the car so it is not a major leak, but it seems to be building up a layer engine oil film under the engine in these areas and it is an going leak since I can wipe this oil film of with my finger. It has been going on for a while undetected since, like I said, there is no actual oil dripping on the ground below the vehicle, but I am trying to find the source of this leakage to fix the problem. Some ideas (more like guesses) are that it could be the valve cover gasket or the oil pan gasket although I don't know if either of these could cause the oil to be present in these areas or it could be coming from a different place altogether that might be known to be oil leak sources Any ideas or suggestions would be welcomed. Pictures of the top of the engine/valve cover are also included.