1. A method for high dynamic range imaging, comprising steps of: a) operating at least two cameras to capture at least two respective images of a scene with different exposures, wherein each of the at least two cameras has its corresponding camera exposure response function; b) adjusting the captured images to a same exposure according to the exposure response function of the corresponding camera and defining a plurality of characteristic spots in each of the images; c) combining the characteristic spots corresponding to the images to get a disparity map of the characteristic spots; and d) applying the disparity map and combing the images to form a synthetic image.