15. A system for generating invisible junctions, the system comprising: a processor; a feature determination unit stored on a memory and executable by the processor, the feature determination unit having an input and an output for applying a distance transformation to an electronic document to generate a distance transform, for detecting a skeleton in the distance transform, for determining junction points in the skeleton as the invisible junctions, the junction points having a distance transformation value based on the distance transform and for determining a junction size that is based at least in part on the distance transformation value, the input of the feature determination unit coupled to receive the electronic document; and a descriptor creation unit stored on the memory and executable by the processor, the descriptor creation unit having an input and an output for creating a feature descriptor for each invisible junction, the feature descriptor including the junction size, the input of the descriptor creation unit coupled to the output of the feature determination unit to receive information about the invisible junctions, the output of the descriptor creation unit providing the feature descriptors.
15. A system for generating invisible junctions, the system comprising: a processor; a feature determination unit stored on a memory and executable by the processor, the feature determination unit having an input and an output for applying a distance transformation to an electronic document to generate a distance transform, for detecting a skeleton in the distance transform, for determining junction points in the skeleton as the invisible junctions, the junction points having a distance transformation value based on the distance transform and for determining a junction size that is based at least in part on the distance transformation value, the input of the feature determination unit coupled to receive the electronic document; and a descriptor creation unit stored on the memory and executable by the processor, the descriptor creation unit having an input and an output for creating a feature descriptor for each invisible junction, the feature descriptor including the junction size, the input of the descriptor creation unit coupled to the output of the feature determination unit to receive information about the invisible junctions, the output of the descriptor creation unit providing the feature descriptors. 16. The system of claim 15 , further comprising a database to store the feature descriptors, the output of the descriptor creation unit coupled to the database.