Thomas Frank Stahovich

20050281467, Dec 22, 2005

May 26, 2005

11/138577

Thomas Stahovich - Riverside CA, US

G06K009/46

382202000

A method of analyzing a symbol comprised of one or more drawn strokes is comprised of calculating the speed of drawing along each stroke. A curvature magnitude along each stroke is calculated. An initial set of candidate points defining initial segments is identified using the calculated speed and curvature metric magnitude. The initial segments are classified as a type of primitive. The initial segments are compared to the original stroke. Merging and splitting of certain of the initial segments may be performed in response to the comparison to produce new segments which are classified as a type of primitive. Because of the rules governing abstracts, this abstract should not be used in construing the claims.

20040037463, Feb 26, 2004

Jan 24, 2003

10/350952

Christopher Calhoun - Mountain View CA, US
Thomas Stahovich - Mars PA, US

G06K009/18
G06K009/46

382/186000, 382/202000

We disclose a trainable recognizer for multi-stroke symbols. Pen speed and the curvature are examined to segment a stroke into the constituent primitives. The primitives are determined to be lines or arcs using, for example, a least squares best fit method. Symbol recognition (training) results in the construction of definitions consisting of the constituent geometric primitives (lines and arcs), the properties of individual primitives, and the geometric relationships between them. A definition is learned by examining a few examples of a symbol and identifying which properties and relationships occur frequently. Thereafter, during symbol recognition (matching), an unknown symbol is identified by determining which definition matches the unknown with the least error. We disclose two recognition methods. One assumes that the primitives of a symbol are always drawn in the same order. This method is fast, but requires some care from the drawer. The other method uses a form of best-first search, with a speculative quality metric and pruning, to recognize symbols when the drawing order is varied. During both training and recognition, multiple primitives can be drawn in the same pen stroke.