U. Glaeser

FIGURE 42.39 Boxplots of time to enter a 42-word message using three different text input methods on a PIA
device: an on-screen QWERTY keyboard, a word-based handwriting recognizer and a character-based handwriting
recognizer. Median writing throughput were 15.9, 13.6, and 11.4 words-per-minute respectively.
FIGURE 42.40 Write-anywhere text input method for
mobile devices. Example of an Address Book application
with the Company field appearing with focus. Hand
written input is not restricted to a delimited area of the
screen but rather can occur anywhere. The company
name “Data Warehouse” has been written.
Furthermore, the authors believe that the time gap between these two input methods will be reduced in
the case of European languages that have accents, since they require additional key presses in the case of
the soft keyboard.
As one can expect, the modeless and time advantage of a word-based input method over a character-based
one comes at the expense of additional computational resources. Currently, the word-based recognition
engine requires a 10×
increment in MIPS and memory resources compared to the character-based engine.
One should also say that, as evidenced by the range of the timing data shown in the above plots, there
isn’t a single input method that works best for every user. It is thus important to offer users a variety of
input methods to experiment with and choose from.
Write-Anywhere Interfaces
In the same way that writing words, as opposed to writing one letter at a time, constitutes an improvement
in terms of “naturalness” of the user experience, we must explore recognition systems capable of handling
continuous handwriting such as phrases. For the kind of mobile devices we’ve been considering, with
very limited screen real estate, this idea leads to the notion of a “write-anywhere” interface where the
user is allowed to write anywhere on the screen, i.e., on top of any application and system element on
the screen (see Fig. 42.40).
© 2002 by CRC Press LLC