1. A method to identify a potential target from image data representing a scene, comprising: receiving at least two frames of image data from at least one imaging sensor; performing at least one of a pre-detection temporal fusion and a pre-detection spatial fusion of the frames of image data; thresholding the fused image data after performing the step of performing; and identifying candidate targets from the thresholded image data, wherein the pre-detection temporal fusion comprises temporally integrating image data from a said imaging sensor across a plurality of time frames and the at least two frames of image data are from the sensor; and the pre-detection spatial fusion comprises fusing the image data from a plurality of said imaging sensors across a single time frame and the at least two frames of image data include at least one frame of image data from two different sensors.