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Visual sensor networks are being increasingly employed as a tool for monitoring and surveillance of wide areas. Due to the relatively high power consumption characteristics of cameras, as well as their more stringent processing, storage, and communication requirements, it is important to carefully evaluate the different modes of operation of these systems, in order to devise energy–aware resource management policies. The ultimate goal is to deliver adequate application–level performance (eg, maximize the probability of detecting events), yet maximally prolonging the system’s operational lifetime. In this paper we present an accurate power consumption analysis for the different elementary tasks forming the duty cycle of a visual sensor node in a wireless camera network testbed. We also present a number of different duty cycle configurations, and provide direct energy consumption measurements for each one of them. Based on the energy consumption characterization we conducted for the elementary visual sensing tasks, we explore the possibility of predicting the lifetime of a visual sensor network system.