1. A system for computing class identifiers for three-dimensional pixel data comprising: a plurality of class identifying processors, each class identifying processor having a plurality of inputs for at least one pixel value and a plurality of class identifiers for pixel values neighboring the at least one pixel value and each class identifying processor being configured to generate a class identifier for the at least one pixel value input with reference to the class identifiers for the neighboring pixel values; and a data grouper operatively connected to a first memory and the data grouper being configured to retrieve a plurality of pixel values from the first memory and a plurality of class identifiers for pixel values neighboring the retrieved pixel values.