United States Patent 7,174,043
Lossev , et al. February 6, 2007

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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.


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Inventors: Lossev; Ilia (Mountain View, CA), Bagotskaya; Natalia (Mountain View, CA)

Assignee: EverNote Corp. (Sunnyvale, CA)

Appl. No.: 10/374,482

Filed: February 25, 2003

Current U.S. Class: 382/187 ; 382/186

Current International Class: G06K 9/00 (20060101); G06K 9/18 (20060101)

Field of Search: 382/159,173,181,186-188,199,201-203,209,218,226,229