# Graphical Decoding

Graphical decoding is the process of reverse-engineering a graph and trying to determine the graphical components and mapping rules.

There are two steps:

1. Identify the graphical components
2. Identify the mapping rules

More precisely,

1. First, identify the visual marks. Then, try to determine what data items the marks represent. (marks$$\rightarrow$$data items)
2. Identify the visual channels. Then, determine what data attaributes the channels represent. (channels$$\rightarrow$$data attributes)

Note that for network graphs, we usually have two types of marks, one for nodes and another for links.