Abstract: A method is presented to calculate the relative contribution of different tissues, or tissue mix, to at least one data element in a medical object data set, the medical object data set containing data elements, the data elements assigning data values to respective positions in a multi-dimensional geometrical space containing more than one tissue, by means by which parameters are calculated for the at least one data element, the parameters being dependent on the data value of the at least one data element and data values of surrounding data elements in the neighborhood of the at least one data element, the parameters being further compared to combinations of said parameters for data elements occurring in the region of boundaries between tissues.

Abstract: A method of constructing an object data set of data elements representing a physical property is described, in which the construction of the object data set includes assigning attributes to respective data elements. Such attributes are used, for example, in volume rendering. The construction of the object data set is achieved in such a way that the relative contributions of the physical property to the values of the respective data elements are derived on the basis of the relative contributions of the physical property to the data values of the data elements. These contributions are calculated by modeling transition changes in the image using a plot of grey value and gradient magnitude. Sampling of data points along the maximum gradient allows identification of the ranges of the physical property contributing to the selected voxel and calculation of the relative amounts.