Core Image: CIFilter : I am wasting my 1 question a month on this so please answer it.

    let filter: CIFilter!
    filter = CIFilter(name: "Sepo")
    filter.setValue(image, forKey: kCIInputImageKey)

what is the key doing? is it naming the image that I am putting in or what? It has such a confusing name it makes no sense..




