This command converts a graph into data frame that contains pixels and colors for plotting the graph using f2i command. A graph structure is defined using two data frames, nodes and arcs . Data frame nodes contains at least three fields having type int or float .
First field is considered as horizontal coordinate, second vertical coordinate and third gray level.
Other fields may contain some other node related information and are ignored. Data frame arcs contain at least two fields. They must have type int . Other fields may contain some other arc related information and are ignored. Image is 256 x 256.