| 摘要 |
<p>In a method of image subtraction a series of frames of a subject are taken using a video camera. The subject is illuminated in a manner so that illumination is alternately on, then off for successive fields within the image frame. A single frame is grabbed and an absolute difference between the odd field and the even field within that single image frame is determined. The resulting absolute difference image will represent the subject as illuminated by the system illumination only, and not by any ambient illumination, and can then be used to identify the subject in the image.</p> |
