Handwriting Recognition

Where space is limited, as with a PDA keyboard, typing can be slow and frustrating. Writing data into the PDA would obviously be a much more sensible idea, but the complexity involved in making handwriting recognition work is immense.

The problem is that vector, line-drawn shapes do not make words. So what is the difference between a drawing of a house and the word shape for wombat, for example? The human eye, of course, recognizes one as being a drawing and the other a word. There are two approaches a computer can take to resolvin the matter. The easy approach is the one taken by the Graffiti recognition system. It understands each letter shape as a unique pattern for that letter, and converts each shape to its corresponding letter. There’s no attempt at understanding words or context. To make it even easier, Graffiti uses some special character shapes which the user of the system has to learn.

The approach taken by Newton was much more ambitious. It attempted to read the user’s writing and convert it into words. It sought to learn the way the user wrote, based on some standard test scripts and some interactive tutorials. This approach becomes increasing effective as the system recognizes more and more of the user’s handwriting style. With Newton, it was possible to set up multiple user writing personalities, and thus it was important to always ensure that Newton always used the correct personality for a given user to avoid its knowledge base becoming polluted.

The apple was key to Newton, but sadly the Newton was a costly mistake for Apple. It will be remembered for the over-hype and for its bold, but ultimately unsuccessful attempt to solve the problem of handwriting recognition. The success of the Graffiti approach, on the other hand, was emulated by other developers. Communication Intelligence Corporation’s (CIC) Jot and ParaGraph’s CalliGrapher were two such systems commonly used by Windows CE and EPOC-based PDAs.

Originally, the Windows CE based Pocket PC platform provided two means of data entry, via a Soft Keyboard or – for those more comfortable with writing with a stylus – via the Letter Recognizer/Transcriber application. On selection of the former, a tablet of alphabetic characters appears in the familiar QWERTY format. The required characters are entered into the document window simply by tapping the required character with the stylus. The latter recognizes letters written with the stylus, supporting word recognition to speed data entry. It also allows complete words to be moved around using cut & paste.

The subsequent Pocket PC 2002 version added two new text input options: Block Recognizer, which accepts Palm-style Graffiti and Transcriber, which recognizes cursive script. Microsoft claims that the technology underlying the former is proprietary, and not licensed from Palm. Since the introduction of what amounts to a Graffiti emulator appears to be motivated by a desire to win market share from its rival, it would be surprising if this wasn’t true!