The present invention relates to an image processing device and a corresponding image processing method for processing a multi-dimensional data set of image data, in particular of three-dimensional medical volume image data, including a segmentation unit (6, 16, 26) for a segmentation of an image object in said data set. Further, the present invention relates to a computer program for implementing said image processing method on a computer. In order to allow for a segmentation which is robust in terms of vulnerability to image artifacts and accurate in terms of reflecting anatomical details, wherein the results of the segmentation are achieved within reasonable short processing time an image processing device is proposed which comprises—model-based segmentation means (61, 161, 261) for performing a model-based segmentation (32) of said data set for obtaining a multi-dimensional model representing a first approximation of said image object; data-driven segmentation means (62, 162, 262) for performing a data-driven segmentation (33) of said multi-dimensional data set for obtaining a multi-dimensional subset of said multi-dimensional data set representing a second approximation of said image object; optimizing means (63, 163, 263) for adapting said model and/or said subset for optimizing a similarity value between said first and said second approximation; and —selecting means (64, 164, 264) for selecting said adapted model or said adapted subset as a segmentation of said image object.