LipiTk: Core Toolkit 1.0

Lipi Core Toolkit 1.0

Highlights

LipiTk 1.0 uses open standards such as UNIPEN for the representation of digital ink and its annotation, facilitating the creation of shareable linguistic resources within the community. There is no annotation tool shipped along with LipiTk in version 1.0. The first version of the toolkit provides robust implementations of tools, algorithms, scripts and sample code necessary to support the entire process starting from the collection of handwritten data, to the deployment and integration of a robust engine, for a particular set of shapes or characters.

Architecture

Supported Platforms

LipiTk 1.0 can be installed on any of the following mentioned platforms:

Windows XP Professional
Windows 2000 Professional edition
Red hat Enterprise Linux Edition 3.0
GNU Linux 2.6.9.22
GNU Linux (Ubuntu) 2.6.14.6

System Requirements

Disk Requirements

LipiTk 1.1 packages for Windows and Linux, both are of size 1.5MB, and require 6MB of space after extraction.
Building the package requires 40MB of free space.

Software Requirements

Lipi Engine

Main shape and word recognition interface for client applications. Given the project and profile name, Lipi engine performs following actions

Load the DLL of the shape recognizer specified in profile config file.
Create and return the instance of shape recognizer.

Using the instance returned by Lipi engine, applications can interact with the recognizer for training and testing of the algorithm.

Generic Data Structure Library

Generic data structure library defines the classes used to store the digital ink.

LipiTK common class	Description
Trace	Class containing contiguous series of coordinates from a pen down event to the next immediate pen up event
TraceGroup	Contains set of traces that have similar characteristics.
TraceFormat	Holds information about the type and number of channel data available at each pen point
ScreenContext	Holds the co-ordinates of the writing area provided

Preprocessing

The generic preprocessing module provides implementations of commonly used shape/character preprocessing operations. Lipitk provides following preprocessing operations

LipiTK proprocessing operations	Description
Moving-average smoothing	Smoothing the stroke by averaging (x,y) values within a local window.
Size normalization	Normalizing the size of the incoming trace group to a default value. the normalized is configurable.
Dehooking	Removal of hook artifacts at the ends of strokes resulting from slippage and/or pen-tip-switch latency.
Equi-distant resampling	Resampling to obtain equi-spaced points along the stroke trajectory

All of the operations have configuration options that can be varied using corresponding properties captured in a configuration file.

Recognizers

Shape Recognizers

LipiTK Shape Recognition Modules	Algorithm used
PCA recognition module	Principal Component Analysis (subspace classification)
DTW recognition module	Dynamic Time Warping

Word Recognizers

LipiTK Word Recognition Modules	Algorithm used
Boxed-field recognition module	Boxed-field recognition (can be configured to call PCA, DTW or any custom shape recognition module )

Utility Classes

The utility classes include various infrastructure classes which provide simple utility functions to other modules.These include

Classes to read/write UNIPEN ink files.
Classes to read the key-value pairs defined in Lipitk config files.
Tokenizer class to split a string on the delimiter passed.
Class to provide logging facility.

Scripts

LipiTK Scripts	Description
listfiles.pl	Generates a file containing a list of filenames from a regular expression mapfile, for the purposes of training/testing a shape recognizer.
package.pl	Perl-based package maker
genmake.pl	Creates the default makefile under running directory
benchmark.pl	This script performs training, testing and evaluation of a shape recognizer. It is useful when these actions need to be performed repeatedly in the course of experimenting with shape recognition algorithms or tuning parameters.
eval.pl	Perl based tool for algorithm evaluation

Implementation Details

Implementation Language	Tools required to build/use	Modules
C++	Windows : Visual Studio Linux : gcc	Lipi Engine Generic Data Structure Library Preprocessing Recognizers Utility Classes
Perl	Perl	Scripts

Enhancements & Bugs Fixed

First version of Lipi core toolkit.

Known Issues

On Windows platforms, if the STL’s string data type is used in a client application and passed by reference
to a DLL function, the application crashes when the string variable goes out of scope. This is the known
defect in Microsoft’s STL library.

For details see: http://support.microsoft.com/default.aspx?scid=kb;en-us;813810

Workaround
For the detailed list of issues and fixes refer :
- http://support.microsoft.com/default.aspx?scid=kb;en-us;813810
- http://www.dinkumware.com/vc_fixes.html
The file path specified in list files for training or testing, can not contain spaces. The executable runshaperec reports an error, and training or testing fails.

Workaround
Do not use directory or files names with spaces in them, or (for Windows platforms) use the DOS path
instead (e.g. for C:\program files, use “C:\progra~1”).

Backward Compatibility