Image analysis – Applications – Personnel identification
Reexamination Certificate
1998-03-18
2002-05-21
Boudreau, Leo (Department: 2621)
Image analysis
Applications
Personnel identification
C382S123000, C382S160000, C382S181000, C382S186000, C382S187000, C382S218000, C073S865400, C340S005820, C348S161000
Reexamination Certificate
active
06393138
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of creating registration signature data in a signature collation system. More particularly, the present invention relates to a method of creating registration signature data in a system in which attestation of a person is performed based on the dynamic characteristics of a signature.
2. Description of the Related Art
A handwritten character recognition method by which written characters are recognized has been utilized as an input method for word processors or a signature collation method for specifying a writer. Under a handwritten character recognition method which has already been in actual use as an input method, characters are input in the block style under specified constraints on the style of typeface, and the thus-input characters are converted into coordinate information. The thus-converted coordinate information is verified by comparison with coordinate information relating to character data which have been stored beforehand. As a result of collation, the characters are recognized as matched. If characters are carefully written in the block style at comparatively slow speed in the manner as previously described, the characters can be sufficiently recognized through use of only coordinate information because under such conditions each of the strokes of the characters becomes clear by virtue of visual feedback to the writer and hence the shape of the characters becomes stable.
In contrast, in a case where the character recognition method is applied to an input method which does not pose any restriction on the style of typeface at the time of input of characters or to a signature collation method, there must be recognized not only characters written in the block type but also cursively written characters. When characters are cursively written, writing motion becomes faster and does not involve any substantial visual feedback to the writer. In this case, the characters become less identifiable, and separation of a resultantly acquired pattern into strokes becomes difficult. This is because an expansion or contraction of the pattern in the direction of the time axis or in the direction of stroke, or the difference between the input pattern and a pre-registered pattern, becomes greater. For this reason, a matching rate is extremely low, rendering identification of characters difficult.
Another method is to enable recognition of characters without involving the separation of characters into strokes by application of time-series coordinate information and writing pressure. This method employs a pattern matching information stemming from variations in writing action.
In the dynamic processing matching technique, variations in the writing motion are corrected with regard to the time axis or the arc length axis through use of a warping function which minimizes a cumulative error between patterns to be checked. Patterns are matched with each other on the basis of the coordinates and writing pressure that have been corrected so as to compensate variations in the writing motion, thereby enabling recognition of cursively handwritten characters.
Verification based on the addition of writing pressure information to time-series coordinate information or normalization of input patterns by DP matching contributes to an improvement in the recognition rate of handwritten characters. However, in the case of application of the dynamic processing matching technique to recognition of cursively written characters or signature collation, a false signature may be erroneously recognized as a genuine signature. Therefore, in its present form, the dynamic processing matching technique cannot be put into practical use.
Japanese Patent No. 1,822,532 [Japanese Patent Publication (kokoku) No. 5-31798] entitled “A Method of Recognizing Handwritten Characters Online” describes a practical technique that is based on dynamic processing matching. Under this method, when the degree of difference between a registered pattern and an input pattern of handwritten characters is calculated by use of dynamic processing matching, time-series coordinate information and writing pressure information are simultaneously processed by the assignment of optimum weighting coefficients to the time-series coordinate information and writing pressure information. As a result, the difference is reduced, which in turn contributes to an improvement in the collation rate of authenticity and a reduction in processing time.
As mentioned previously, even in the case of unclear characters which cannot be separated into strokes, processing of the time-series coordinate information and writing pressure information relating to handwritten characters enables recognition of the characters. Further, even in the case of cursively handwritten characters, the characters can be recognized in practice, as a result of a further improvement in the dynamic processing matching technique that compensates variations in writing motion in order to correct cumulative errors.
In a static signature collation system, an image scanner or an image OCR is used as a tool for reading out characters. In contrast, in a dynamic signature collation system, a stylus pen is generally used.
FIG. 1
shows a schematic view of a dynamic signature collation system utilizing a stylus pen. When characters are written on a tablet 2 through use of a stylus pen 1, signals representing characters are sent to a collation section, where signature collation is performed.
Such a tablet and stylus pen are important devices that affect ease of use. Therefore, recently these devices have been improved. For example, a tablet formed from a liquid-crystal panel and a wireless stylus pen having no signal cable have come into use. Further, in place of a piece of hardware dedicated to signature collation, a personal computer has come into use. In this case, signature collation is performed by software or a program.
The processing performed in the collation section is composed of three steps; i.e., pre-processing
ormalization, character extraction, and identification/judgment. Information from the stylus pen includes relative coordinates (x, y) relative to the start point of a signature, and writing pressure p. Specifically, information as shown in Table 1 is obtained every unit time.
TABLE 1
t
x
y
p
t
1
x
1
y
1
p
1
t
2
x
2
y
2
p
2
t
3
x
3
y
3
p
3
.
.
.
.
.
.
.
.
.
.
.
.
Since handwritten characters are not necessarily consistent, collation of a signature involves difficulty caused by variation in the direction of writing and in size, and hardware noise. The pre-processing
ormalization removes these variations and noise and performs normalization in order to enable comparison with standard character patterns. Specifically, in the pre-processing, there are performed removal of excess series of points (sampling based on amount of relative movement), removal of random noise that depends on hand shake and resolution of a tablet (smoothing through load shift), removal of isolated data caused by erroneous operation of the tablet, and like operations.
After completion of the pre-processing, as shown in
FIG. 2
, the size and position of input characters are normalized. Subsequent to the above-described processing, characteristics of the characters are extracted, and identification/judgment processing is performed.
In Japan, seals have been accepted with absolute trust as means for personal authentication for settlements at financial institutions, agreements, and the like. By contrast, handwritten signatures have not been authorized as means for personal authentication as is the practice in western countries. However, since computerization and enhancement of communication techniques have advanced worldwide in various fields, personal authentication by means of seals has been found troublesome with regard to international transactions and future computerization in Japan.
Although seals are considered secure when a person imprints his/her own seal, seals are highly insecure in the field of comput
Boudreau Leo
Cadix Inc.
Mariam Daniel G.
LandOfFree
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