Compare images

Is there some way to get the image inside a region and compare to a list of images?

some games have loot bags and one way of collect info about items were dropped is doing like this:

if exists("item1")
if exists("item2")
if exists("item3")

// very slow way

I guess would be better if i crop the region and just compare to detect what item it is. Like:

region = Region(0, 0, 50, 50):getImage()

bestMatch = getBestMatch(region, tableOfImages);

Thank you