Dennis C Hunt

US Patent:

50955128, Mar 10, 1992

Filed:

Oct 24, 1988

Appl. No.:

7/261956

Inventors:

Lawrence G. Roberts - Woodside CA
Dennis L. Hunt - Burlingame CA

Assignee:

NetExpress Systems, Inc. - Foster City CA

International Classification:

G06K 936

US Classification:

382 56

Abstract:

Bit-mapped and compressed image data are converted one another through an intermediate image data or code form wherein each image is represented by a list of sublists, each sublist being itself a list of numerical values representing run lengths transistions from one type of picture element (pel) to a second and opposite type of picture element (pel) (e. g. , a black pel and a white pel). Hence the intermediate code data structure according to the invention is termed a transition list or TL code or data structure. The data structure and coding rules are defined by rules relating to code type, code word length and code word interdependence. A specific conversion process specifies that the transition list be composed of sublists wherein each represents a scan line. The preferred form of intermediate code is a fixed word-length transition list, that is, a serial list of values representing run lengths of either "black" picture elements or "white" picture elements stored serially in digital data format having a fixed word length.