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Flexible, Space-Time Segmenter for Handwritten Words

IP.com Disclosure Number: IPCOM000039064D
Original Publication Date: 1987-Apr-01
Included in the Prior Art Database: 2005-Feb-01
Document File: 3 page(s) / 55K

Publishing Venue

IBM

Related People

Fox, AS: AUTHOR [+3]

Abstract

The present invention relates to a method for performing segmentation of handwritten words based on spatial and temporal information gathered while a writer scribes words onto an electronic tablet. Spatially, a sequence of points are produced from pen down to pen up. The sequence of points (x and y coordinates) from pen down to pen up is called a stroke. Xmin corresponds to the x coordinate of the leftmost point of the stroke. Xmax corresponds to the rightmost point. The use of temporal information is based on several considerations. First, a writer tends to pause between words. In this regard, the writer's hand is normally moved to a new position before a next word is written, thus introducing a delay between words. Second, the writer typically completes a word by adding "retrograde" strokes (e.g.

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Flexible, Space-Time Segmenter for Handwritten Words

The present invention relates to a method for performing segmentation of handwritten words based on spatial and temporal information gathered while a writer scribes words onto an electronic tablet. Spatially, a sequence of points are produced from pen down to pen up. The sequence of points (x and y coordinates) from pen down to pen up is called a stroke. Xmin corresponds to the x coordinate of the leftmost point of the stroke. Xmax corresponds to the rightmost point. The use of temporal information is based on several considerations. First, a writer tends to pause between words. In this regard, the writer's hand is normally moved to a new position before a next word is written, thus introducing a delay between words. Second, the writer typically completes a word by adding "retrograde" strokes (e.g., dotting an "i" or a "j" or crossing a "t" or an "x" or adding punctuation) before starting a next word. Based on these considerations, several assumptions are made. It is assumed that, when a retrograde stroke is executed, the portion of the handwritten material extending from (a) the normal stroke to which a retrograde stroke is attached to (b) the (current) rightmost stroke of the handwritten material are all part of a single word. It is also assumed that a "normal", or non-retrograde, stroke following a retrograde stroke or sequence of retrograde strokes is likely to begin a new word. A procedure combining spatial and temporal information --each being weighted as desired- is set forth in the flow chart on the next page. In the flow chart, the following definitions apply: Xmin (stroke) = minimum x value of stroke

Xmax (stroke) = maximum x value of stroke

R = xmax of all prior strokes on the line

L = xmin of the retrograde stroke which began a retrograde

sequence if still in a retrograde sequence,

= R otherwise

T1 = 1/5 line spacing

T2 = 1/2 line spacing

S = 1 if the current stroke is a retrograde stroke,

= O otherwise

N = 1 if the current stroke is a normal stroke immediately

following temporally a retrograde sequence of strokes,

= O otherwise

(Image Omitted)

Line spacing is represented by the number of resolution points corresponding to the height of a normally-written upper-case character. The subroutine ATTACH in step 8 attaches the new stroke to as many of the existing clumps of strokes as possible. It does this by using a metric to compare the new stroke to another stroke and, if the value of the metric is less than a threshold, then the new stroke is added to the word segment containing the other compared stroke. Each new stroke

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is, effectively, compared to the strokes of all currently existing word segments. If the new stro...