1. A method of evaluating data associated with direct volume renderings, comprising: electronically subdividing a volume rendering data set into neighborhoods with local histograms; automatically electronically analyzing a plurality of the local histograms; programmatically distinguishing different materials with overlapping intensity values using at least one range weight data value, wherein the at least one range weight data value is derived as the portion of the pixel or voxel intensity values in the local histogram being within a predefined partial range wherein the at least one range weight data value is used to electronically establish whether a sufficient portion of each local histogram is within a defined partial range, and wherein the programmatically distinguishing step uses the at least one range weight data value to determine whether a particular type of material is associated with different neighborhoods having at least some intensity values inside the defined partial range such that the material can be (a) associated with some of the neighborhoods having less than all of the intensity values inside the partial range with a range weight data value below 100% but above a threshold value and (b) not associated with some of the neighborhoods having some of the intensity values inside the partial range with a range weight data value above 0% but below a threshold value; generating at least one of a visualization attribute or visualization parameters for the pixels or voxels based on the range weight analysis of local neighborhoods used in the programmatically distinguishing step; rendering an image with the programmatically distinguished different materials using at least one of the generated visualization attribute or the generated visualization parameters; and programmatically generating at least one partial range histogram of data based on the analyzing step to carry out the distinguishing the materials step, wherein the partial range histogram is populated based on the at least one range weight data value and includes local neighborhoods that have a sufficient number of voxels with intensity values within the defined partial range and can include local neighborhoods having one or more voxel intensity values outside the partial range and can exclude local neighborhoods that have voxel intensity values inside the partial range.