1. A method comprising: receiving first image data captured by a camera-equipped portable device, the first image data representing an object; determining one or more descriptors relating to the object in the image data, said determining including collecting descriptors associated with one or more other images; processing said descriptors in discerning whether the first image data represents an object that is likely of a first class or a second class or a third class, said processing being performed by one or more electronic processors configured to perform such act; and taking an action dependent on whether the first image represents an object that is likely of a first class or a second class or a third class.