R user Arthur Charpentier attempts to use the raster library and R functions to find Waldo in a “Where's Waldo” image:
Sadly, it turned out that Waldo was a bit too tricky to spot using these techniques. But Arthur did have more success identifying the US flag in a shot from the Apollo mission, and identifying answers in the form for a multiple-choice test. All of the R code is provided at the link below, so that's a great place to start if you're looking to do some image analysis in R yourself.
Freakonometrics: Finding Waldo, a flag on the moon and multiple choice tests, with R