The disclosure relates to an image processing method for estimating a brain shift in a patient, the method involving: the processing of a three-dimensional image of the brain of a patient, acquired before a surgical operation, in order to obtain a reference cerebral arterial tree structure of the patient; the processing of three-dimensional images of the brain of the patient, acquired during the operation, in order to at least partially reconstitute a current cerebral arterial tree structure of the patient; the determination from the combination of the reference and current cerebral arterial tree structures, of a field of shift of the vascular tree representing the shift of the current vascular tree in relation to the reference vascular tree; the application of the determined field of shift of the vascular tree to a biomechanical model of the brain of the patient in order to estimate the brain shift of the patient; and the generation, from the estimated brain shift, of at least one image of the brain of the patient, in which the brain shift is compensated.