Multi-scale recognizer for hand drawn strokes
First Claim
Patent Images
1. A handwritten character recognition apparatus comprising:
- means for sampling a known handwritten character;
n filters, where n is an integer ≧
2, with the first such filter filtering out direction changes less than a first angle in said known handwritten character to provide a first filtered known character, with the second such filter filtering out direction changes less than a second angle in said first filtered known character, where said second angle is greater than said first angle for providing a second filtered known character and so on, with the nth filter filtering out direction changes less than an nth angle in the (nth-1) filtered known character, where the nth angle is greater than the (nth-1) angle, to provide an nth filtered known character; and
storing the n filtered known characters for subsequent comparison to an unknown handwritten character.
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Abstract
A known hand drawn stroke is serially sampled at different scales by n angle filters to provide n filtered known strokes at n different scales. An unknown hand drawn stroke is sampled in a like manner to provide n filtered unknown strokes at n different scales. Filtered unknown strokes are compared with filtered known strokes. If there is a comparison within predetermined limits at any scale, the unknown hand drawn stroke is recognized as being the same as the known hand drawn stroke.
52 Citations
14 Claims
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1. A handwritten character recognition apparatus comprising:
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means for sampling a known handwritten character; n filters, where n is an integer ≧
2, with the first such filter filtering out direction changes less than a first angle in said known handwritten character to provide a first filtered known character, with the second such filter filtering out direction changes less than a second angle in said first filtered known character, where said second angle is greater than said first angle for providing a second filtered known character and so on, with the nth filter filtering out direction changes less than an nth angle in the (nth-1) filtered known character, where the nth angle is greater than the (nth-1) angle, to provide an nth filtered known character; andstoring the n filtered known characters for subsequent comparison to an unknown handwritten character. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A handwritten character recognition apparatus, comprising:
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means for sampling a known handwritten character; a first means for filtering out direction changes less than a first angle in said sampled known handwritten character to provide a first filtered known character; at least a second means for filtering out direction changes less than a second angle, where said second angle is larger than said first angle, in said first filtered known character to provide a second filtered known character; means for storing said first filtered known character and said second filtered known character; means for sampling an unknown handwritten character; a third means for filtering out direction changes less than said first angle in said sampled unknown handwritten character to provide a first filtered unknown character; at least a fourth means for filtering out direction changes less than said second angle in said first filtered unknown character to provide a second filtered unknown character; a first comparison means for comparing said first filtered unknown character with said stored n filtered known characters; a second comparison means for comparing said second filtered unknown character with said stored n filtered known characters; and means for recognizing said unknown character as said known character if either comparison by said first or second comparison means matches within predetermined limits.
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8. A handwritten character recognition apparatus, comprising:
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means for sampling a known handwritten character; a first means for filtering out direction changes and less than a first angle and lines less than a first length in said sampled known handwritten character to provide a first filtered known character; means for removing any retrace in said first filtered known character; at least a second means for filtering out direction changes less than a second angle, where said second angle is larger than said first angle, and lines less than a second length, in said first filtered known character with any retrace removed to provide a second known character; means for removing any retrace in said second filtered known character; means for storing said first filtered known character and said second filtered known character with any retrace removed; means for sampling an unknown handwritten character; a third means for filtering out direction changes less than said first angle and lines less than a first length in said sampled unknown handwritten character to provide a first filtered unknown character; means for removing any retrace in said first filtered unknown character; at least a fourth means for filtering out direction changes less than said second angle and lines less than said second length in said first filtered unknown character to provided a second filtered unknown character; means for removing any retrace in said second filtered unknown character; a first comparison means for comparing said first filtered unknown character with retrace removed with said stored n filtered known characters with retrace removed; a second comparison means for comparing said second filtered unknown character with retrace removed with said stored n filtered known characters with retrace removed; and means for recognizing said unknown character as said known character if either comparison by said first or second comparison means matches within predetermined limits.
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9. A method of recognizing hand drawn strokes made up of a plurality of line segments connecting xy points, said method comprising the steps of:
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sampling a known hand drawn stroke; filtering out all adjacent line segments in said known hand drawn stroke that form an angle less than a first angle at their common xy point, and replacing said adjacent line segments with a line segment between their uncommon xy points, to form a first filtered known stroke; filtering out all adjacent line segments in said first filtered known stroke that form an angle less than a second angle at their common xy point, and replacing said adjacent line segments with a line segment between their uncommon xy points to form a second filtered known stroke; and storing said first filtered known stroke and said second filtered known stroke for subsequent comparison to an unknown hand drawn stroke. - View Dependent Claims (10, 11, 12, 13, 14)
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Specification