A monitoring camera is connected to an external power source. The external power source has an external maximum power level. Image data is being processed in a first processing state. The monitoring camera detects (202) an event and determines (206) a type of the detected event. An amount of energy in an energy accumulator is determined (208) in the monitoring camera. Based on the type of the event and based on the external maximum power level and based on the determined amount of energy in the energy accumulator, a second processing state is determined (210). The second processing state requires a power level that is higher than the external maximum power level. Image data is then processed (212) in the second processing state.