34. A method comprising: specifying a class network having a class, wherein a membership function defines whether an object of a data network belongs to the class; specifying a process step having a domain and an algorithm, wherein the domain designates the class, and wherein the process step is part of a process hierarchy; receiving pixel values obtained from a digital image; receiving metadata relating to the digital image; and executing the class network and the process hierarchy on a computer that implements the data network by selectively linking a plurality of objects to the pixel values and to the metadata according to the class network and the process hierarchy, wherein the process step is linked to the metadata.
42. The method of claim 34 , wherein the executing that implements the data network comprises performing the algorithm on each object of the plurality of objects that belongs to the class, and wherein the performing the algorithm yields a result, further comprising: determining based on the result whether the objects that belong to the class depict a target region on the digital image; and repeatedly respecifying the class network and performing the algorithm until the objects that belong to the class depict the target region.