US 2004/0165777 A1 · On-line handwriting recognizer

Abstract

A character recognizer recognizes a handwritten input character. A sequence of points in two dimensional space representative of a stroke trajectory forming the input character is gathered. An input Directed Acyclic Graph is built with nodes representative of singular points at the beginning, end, and along the trajectory of the input character and with edges between nodes representative of an edge trajectory formed by the sequence of points of the input character between the singular points. Each edge in the input graph is described based on the shape, orientation and pen lift of the edge trajectory that the edge represents. The input graph is evaluated against model graphs, which are also Directed Acyclic Graphs, for all possible characters to find a path through a model graph that produces a best path similarity score with a corresponding path through the input graph. The input character is identified as an answer character represented by the model graph producing the best path similarity score. Each model graph for a reference character has nodes representative of singular points at the beginning, end, and along the stroke trajectory of the reference character. Edges between nodes in the model graph are representative of an edge trajectory formed by the sequence of points of the reference character between the singular points. Further each edge of the model graph has an “i” vector, a “j” vector and a “k” vector, and the “i,j,k” vectors indicate similarity values associated with the edge trajectory of the reference character and typical shapes, shape rotation and pen lift, respectively.

Claims21

Dependent claims

A method for recognizing an input handwritten character digitized as a sequence of coordinate points in two dimensional space representative of a trajectory making up the input character, the method comprising the acts of:

gathering the sequence of points for the input character;
building an input graph with nodes representative of significant points along the trajectory of the input character and with edges between nodes representative of the trajectory formed by the sequence of points of the input character between the significant points;
describing each edge in the input graph based on the shape and orientation of the trajectory that the edge represents;
evaluating the input graph against model graphs for all possible characters to find a model graph having the most similar path to a path of the input graph and identifying the input character as an answer character represented by the model graph with the most similar path.

1 more element

A system for recognizing handwritten characters based on trajectory segments of one or more strokes making up each character, the system comprising:

a find module identifying singular points of each character trajectory defining a beginning point and end point of each stroke of the character and points of significant curvature along each stroke of the character;
a graph module graphing each character as an input graph made up of nodes connected by edges where each node corresponds to a singular point, each edge corresponds to one or more trajectory segments connecting two singular points;
an edge definition module describing each edge based on the shape, orientation and air percentage of the trajectory segment associated with the edge;
and
an evaluation module evaluating the input graph against all model graphs of a set of reference characters to identify the model graph of a reference character most similar to the input character.

2 more elements

A computer readable medium readable by a computing system and encoding a computer program of instructions for executing a computer process for recognizing a handwritten input character, said computer process comprising:

gathering a sequence of points in two dimensional space representative of a trajectory forming the input character;
building an input graph with nodes representative of singular points at the beginning, end, and along the trajectory of the input character and with edges between nodes representative of an edge trajectory formed by the sequence of points of the input character between the singular points;
describing each edge in the input graph based on the shape, orientation and pen lift of the edge trajectory that the edge represents;
evaluating the input graph against model graphs for all possible characters to find a path through a model graph that produces a best path similarity score with a corresponding path through the input graph and identifying the input character as an answer character represented by the model graph.

1 more element

Dependencies are inferred from the claim text.

On-line handwriting recognizer

Life of this patent

On-line handwriting recognizer

Life of this patent

Abstract

Claims21