1. A perceptual-segmentation system, comprising: a computer; and one or more perceptual-segmentation programs, stored within the computer and executed by the computer, that identify regions within an image; for each identified region, compute or access each of one or more pixel-feature values for pixels within region, using the one or more pixel-feature values computed or accessed for pixels within the region, compute one or more region-feature values, and using the one or more region-feature values, determine a region type for the region and associating the region type with the region; and store the associations of region types with regions for use in subsequent image-processing tasks; wherein the one or more perceptual-segmentation programs, stored within the computer and executed by the computer, identify regions within the image by: for each of a number of specific object-identifying methods, applying the object-identifying method to locate occurrences of objects of a specific type in the image; and disambiguating any regions of overlap of two or more objects identified by the object-identifying methods.