1. A one camera fault detection method, comprising: exposing an image frame of an to be monitored by an area image sensor; wherein the method further comprises; transmitting an image part of said image frame of the object to be monitored to an image data processing device; analysing said image part of said image frame of the object to be monitored by said image data processing device, wherein; if said image part of said image frame of the object to be monitored is detected to comprise at least one predefined event, said image data processing device is arranged to transmit a trigger signal for triggering said area image sensor so that said area image sensor is reconfigured to expose a further image frame of said at least one predefined event and to transmit an image part of said further image frame of said at least one predefined event to said image data processing device for further analysis, wherein conditions in said image part of said image frame of the object to be monitored determines the size and position of said image part of said further image frame of said at least one predefined event to be transmitted, and if said image part of said image frame of the object to be monitored is not detected to comprise a predefined event, said area image sensor continues back to expose an image frame of the object to be monitored and to transmit an image part of said image frame of the object to be monitored to the image data processing device.