System and method for representing handwritten handwriting parameters for its verification.
Patent 5347589 USA, IPC G06K 9/00. — Published 13.09.94.
System and method for representing handwritten handwriting parameters for its verification.
In the practice of law enforcement agencies and security services, situations often arise that require identification or verification of handwriting of individuals. Such verification can be carried out either in the presence of the person being verified, or remotely from a remote terminal, as is done, for example, in access control systems to computing facilities and resources. There are two main approaches to carrying out such verification:
- the use of automated systems and methods for processing signature reproduction dynamics data in order to determine their coincidence and confirm the authenticity of the presented signature;
- the use of comparison systems and methods with the simultaneous presentation of the control and presented signatures on the display screen for analysis by the operator, who concludes that they are identical.
Among the known systems using the first approach, one system generates an analog signal proportional to the tangential velocity of the pen movement on the paper surface and determines the degree of correlation between the signal generated and the control signal.
Another system uses a pen with an accelerometer and a pressure sensor to verify handwriting. The readings from these devices are used to determine the authenticity of handwriting. Another system determines the X and Y components of the pen velocity, and the difference in the velocity vectors is used as a measure of handwriting discrimination.
Systems based on the first approach differ from systems based on the second approach in greater verification accuracy, although they also have certain drawbacks.
The inventors propose a verification method and system that take into account the advantages of both types of systems. The proposed method and systems are developed on the basis of a practically proven principle, which consists in the fact that for effective handwriting verification, the operator must be presented on a recording device (for example, a video monitor) with both the reproduced handwritten text and one (or more) dynamic handwriting parameters (tangential velocity of the pen, pressure of the pen on the paper, etc.) for comparison with the control data.
The proposed system includes a graphic tablet for reproducing handwritten text and converting the X, Y coordinates of the pen moving on the tablet surface into digital form. The speed of analog-to-digital conversion is from 50 to 200 samples per 1 second. Commercially available tablets also provide the pressure of the pen on the paper when reproducing handwritten text.
The data output by the tablet are fed to a calculator, which calculates the tangential velocity of the pen movement and its axial pressure on the tablet surface, as well as changes in these parameters over time. This information is also entered into the system memory for use in comparison with other handwriting samples. The data from the calculator output are fed to a video display and/or a printer. The trace of the pen movement on the tablet surface and the tangential velocity of the pen movement are reproduced on the display screen. The trace of the pen movement is modulated by fluctuations in the tangential velocity during its movement, which provides additional information for handwriting verification. A control handwriting sample and the corresponding dynamic parameter can also be reproduced on the display screen for comparison. If necessary, other dynamic handwriting parameters can also be reproduced, such as the axial pressure of the pen, its tilt and their changes over time. Changes in axial pressure or velocity can be represented by different shades of color on a color display or gradations of halftones on a black-and-white display. The time parameter can be represented by periodically repeating time marks on the screen. All calculations and presentations of parameters are performed according to a given program.