# Pattern Features

A PatMax pattern is a collection of features. An individual feature is defined to be a continuous boundary between regions of dissimilar pixels. The regions can have different intensity, contrast, or texture, and can be open or closed.

PatMax pattern features are represented by an ordered list of feature boundary points. A feature boundary point has a location and an angle along with links to its neighboring boundary points. The angle of a feature boundary point is the angle between the image coordinate system x-axis and a line drawn through the feature boundary point perpendicular to the feature boundary and in the dark-to-light direction.