A data processing method for determining atlas data and comprises information on a description of an atlas image of a general anatomical structure. The method performed by a computer comprises: acquiring patient data which comprise a description of a set of images of an anatomical structure of a set of patient images and each patient image is associated with image representation parameters; acquiring model data which comprise information on a description of a model image of a model of an anatomical structure of a patient; determining matching transformations which are constituted to respectively match the set of patient images of the set of patients to the model image by matching images associated with the same parameter set; determining an inverse average transformation by applying an inverting and averaging operation to the determined matching transformations; and determining the atlas data.