Primitives chain code [image analysis]

The primitives chain code (PCC) is described as an extension of the Freeman chain code, with each PCC codeword representing either a portion of a zero- to three-pixel chain or an endline, junction, or break feature. A simple context-free syntax is described which enables PCC to maintain inherent two-dimensional branching of the line structures. The compression efficiency of PCC is attributed primarily to use of this syntax. Examples are given showing comparisons of coding efficiency for different coding schemes. Advantage is taken of PCC´s compact and feature-based code for aid in image analysis. PCC is described as the lowest level of the thin line code (TLC). TLC is a hierarchy of data structures for use in image analysis of line images. As such, PCC is the link between the image space and feature space. Examples are described of applications such as noise reduction and feature recognition performed on PCC and other TLC levels, and it is shown how analysis is facilitated by the knowledge of context and features