Abstract: Purchase of an item bearing a unique identification code is verified by (a) ascertaining the identification code of an item to be purchased; (b) acquiring data representative of color features of the item to be purchased; and (c) comparing the data representative of color features of the item to be purchased to data representative of expected color features for items having the same identification code. Other physical characteristics of an item, such as height, may also be employed. The disclosed system is also capable of detecting whether a shopping cart is empty or not, and determining whether a non-empty cart is an indication that a theft is being attempted.