Shorthand Handwriting Recognition for Pen-Centric Interfaces

1. Shorthand Handwriting Recognition for Pen-Centric Interfaces Charles C. Tappert1 and Jean R. Ward2 1 School of CSIS, Pace University, New York, USA 2 Pen Computing Consultant, Massachusetts, USA

2. Will provide critical infrastructure for many pen-centric applications Will provide fast text input Will have greatest impact on applications running on small mobile devices Thesis: Pen-Centric, Chatroom-Like Shorthand Interfaces

3. Handwriting Fundamental Property of Writing Handwriting Recognition Difficulties Historical Shorthand Alphabets Online(Pen-Centric) Handwriting Recognition Onlinemore accurate than Offline Recognition Online Info Can Complicate Recognition Process Design Tradeoffs/Decisions Pen-Centric Shorthand Alphabets Pen-Centric Word/Phrase Shorthand Allegro/Chatroom Experimental Shorthand System Agenda

4. Differences between different characters are more significant than differences between different drawings of the same character This makes handwritten communication possible Fundamental Property of Writing

5. Fundamental Property of Writing • Property holds within subalphabets of uppercase, lowercase, and digits, but not across them • “I”, “l”, and “1” written with single vertical stroke • “O” and “0” written similarly with an oval

6. Shape, size, and slant variation Similarly shaped characters – U and V Careless writing in the extreme, almost illegible writing Resolving difficult ambiguities requires sophisticated recognition algorithms, syntax/semantics Handwriting Recognition Difficulties

7. Famous writings were written in shorthand Cicero’s orations Martin Luther’s sermons Shakespeare’s and George Bernard Shaw’s plays We focus on shorthand appropriate for PDAs Two main types of shorthand Non-geometric shorthand Geometric shorthand Small number of basic shapes Shapes reused in multiple orientations Historical Shorthand Alphabets(prior to pen computing)

8. Tironian Alphabet, 63 B.C.

9. Stenographie Alphabet, 1602

10. Stenographie Alphabet, 1602 Geometric shorthand – basic shapes/orientations

11. Moon Alphabet, 1894 • Geometric shorthand – basic shapes/orientations

12. Phonetic alphabets Pitman (1837) Gregg (1885) Systems for the blind Braille (1824) Cursive shorthands Gabelsberger (1834) Other Historical Shorthand Systems

13. Machine recognizes the writing as the user writes Digitizer equipment captures the dynamic information of the writing Stroke number,order,direction,speed A stroke is the writing from pen down to pen up Online(Pen-Centric) Handwriting Recognition

14. Can use both dynamic and static information Can often distinguish between similarly shaped characters E.g., 5 versus S where the 5 is usually written with two strokes and the S with one stroke Online(Pen-Centric) more accurate than Offline (Static) Recognition

15. Online Information Can Complicate Recognition Process • Segmentation ambiguities • Character-within-character problem – cl versus d • Large number of possible variations • E can be written with one, two, three, or four strokes, and with various stroke orders and directions • Four-stroke E has 384 variations (4! stroke orders x 24 stroke directions)

16. No constraints on the user Machine recognizes user's normal writing User severely constrained Must write in particular style such as handprint Must write strokes in particular order, direction, and graphical specification Simplest is one stroke per character, one stroke direction, one shape Design Tradeoffs/Decisions

17. Some of the earliest were for CAD/CAM Others developed for text input on PDAs We review geometric and non-geometric shorthands appropriate for small devices Historical alphabets presented above could be used for machine recognition In addition to shape and orientation, stroke direction can differentiate among symbols Pen-Centric Shorthand Alphabets

18. Allen Alphabet

19. Allen AlphabetBasic Shapes and Orientations

20. Goldberg Alphabet

21. Goldberg AlphabetBasic Shapes and Orientations

22. Graffiti Alphabet(non geometric )

23. Allegro Alphabet (non geometric)

24. Small alphabet one case rather than both upper and lowercase Small number of writing variations per letter preferably only one One stroke per character (character = stroke) allows machine to recognize each character upon pen lift Separate writing areas for letters and digits avoids confusion of similarly shaped letters and digits Simplified Design Tradeoffs/Decisions for Graffiti and Allegro PDA Alphabets

25. Graffiti and AllegroCommercially Successful Shorthands • High correspondence to Roman alphabet • Easier to learn • Graffiti used in Palm OS devices • notably the Palm Pilot and Handspring models • Allegro used in Microsoft Windows devices • Geometric alphabets not successful

26. Pen-Centric Word/Phrase Shorthande.g., Chatroom Shorthand • Further increase speed of text entry • Potential applications • Where input speed important • Where word/phrase abbreviations occur frequently – e.g., email

27. Allegro/Chatroom Shorthand System • Developed for M.S. dissertation • Student was hearing impaired • Developed as output component of communication system • Handwriting to text to speech • Two input writing areas • One for Allegro (all-purpose) • One for chatroom-like words/phrases (e.g., CUL, F2F)

28. Allegro/Chatroom Shorthand System

29. Allegro/Chatroom Shorthand System

30. Allegro/Chatroom Shorthand SystemPreliminary Experimental Results • Allegro/Chatroom pen-centric shorthand input faster than typing text and comparable to typing text and chatroom shorthand characters

31. Will provide critical infrastructure for many pen-centric applications Will provide fast text input Will have greatest impact on applications running on small mobile devices Conclusions: Pen-Centric, Chatroom-Like Shorthand Interfaces