1. A method for automatically distinguishing in-store employees from in-store customers, said method comprising: analyzing video input from cameras deployed in retail stores; identifying location of an in-store employee in data captured from said video input for constructing a model of an in-store employee; learning joint distribution of spatial properties and appearance models of objects in said camera field of view; and distinguishing attributes of in-store employees and of shoppers entering retail stores for constructing a model for an in-store employee, said distinguishing comprising: recognizing patterns of clothes worn by in-store employees; recognizing colors of clothes worn by in-store employees; comparing histograms in a blue channel to separate between histograms supporting more variations of appearance and no obvious spatial appearance clusters, illustrative of patterns belonging to customers and histograms supporting coherent spatial distributions of blue consistent of patterns belonging to employees; and classifying persons into categories of in-store employees and customers based on said identified location of an in-store employee, based on said learning of spatial properties and appearance models of objects in said camera field of view, based on said comparing histograms and based on said distinguishing attributes of in-store employees and shoppers entering retails stores.