1. An image processing method of detecting tag points in a current tagged image of a sequence of tagged images, comprising the steps of: in the current image, estimating points which have optimal intensity values in intensity profiles and labeling said points as candidate points of a tag; using a previously constructed predicted image constituted by predicted tags determined from tag equations of a preceding image of the sequence and from spatial and temporal parameters; and, in the current image, detecting tag points among said candidate points from said previously constructed predicted image; determining tag equations for the current image from said detected tag points, using said tag equations in the construction of a further predicted image for processing a next image of the sequence.