When I get a game cam picture that looks like it might be interesting, but there's nothing distinct in it, I run the picture thru a photo program ( I use The GIMP, which is free ) to enhance it.

Here's Horacio's picture with the brightness turned up quite a bit. It's very grainy in this form, but you can see that there is something large in the foreground.

Often I can see a rough shape, or what might be the eye(s) or an animal, but only by running the photo through a photo editor can I really determine what is there.