Seal Imprint Verification Research Articles

Seal imprint verification via feature analysis and classifications

Abstract Verifying a seal imprint to authenticate the identity is a general and important task in financial industries. The seal imprint attached to a document is often used as a form of authenticity. Therefore, in financial applications, it is often necessary to recognize whether a seal is genuine or forged. In order to simplify the verification, we propose an effective method based on regression analysis to approximate the imprint borders, and use the geometric transformation to adjust the perspective of the detected imprint image. To align the detected image with the original image, the first step is to find four borders and cross each border to obtain four vertices of the rectangular imprints. The Ordinary Least Squares regression is then applied on the outer strong feature points, and the estimated regression line would be taken as the borders. The regression process is repeated several times to estimate border lines as precise as possible. Besides, considering the practical application in taking seal imprints by camera, the imprint is subject to geometric distortion, due to camera perspectives, comparing to the stored genuine imprint image. Therefore, the detected image is geometrically transformed to align its perspective with the genuine imprint. Finally, the SSIM and PSNR are calculated as the decision metrics to check whether the two indexes exceed the predetermined thresholds. Then the imprint is determined as a genuine or forged imprint. The experiments are conducted among various stamping imprints, and the results show the efficiency and effectiveness of the proposed identification approach.

An automatic seal imprint verification approach

The automatic verification of seal imprints is a difficult pattern recognition problem and has a lot of applications in the oriental countries. Several approaches have been proposed in the past 10 years, but all of them were hard to implement in practice because of their drawbacks in the adaptability, reliability and practicality. In this paper, a new automatic seal imprint verification approach is presented. Due to the efficient and accurate registration method, a set of effective features and the elaborate implementations, this approach has satisfied most practical requirements and has been used for a practical check verification system in a Chinese bank.

Attributed stroke graph matching for seal imprint verification

In this paper, a new scheme ∗∗ ∗∗ The basic idea of the new scheme using attributed stroke graph matching for seal imprint verification was first reported at the International Conference on Computer Processing of Chinese and Oriental Languages, Toronto, Canada, August 1988. for automatic seal imprint verification using attributed stroke graph matching is proposed. Our scheme can handle seal imprints under much less constraints. The shape of seals can be a square, an ellipse, a circle, or any close loop. The boundary of the seal imprints is allowed to be imperfect. Furthermore, it is insensitive to the distance between the TV-camera and seal imprints. Experimental results confirm that the proposed scheme might be feasible for practical applications.

Unconstrained seal imprint verification using attributed stroke graph matching

Seal imprint verification by human visual inspection is a serious bottleneck of office automation in Oriental countries. In this paper, we propose a new scheme † † The basic idea of the new scheme using attributed stroke graph matching was first reported at the International Conference on Computer Processing of Chinese and Oriental Languages, (4) Toronto, Canada, August 1988. for automatic seal imprint verification using attributed stroke graph matching. A major advantage of our scheme is that our scheme can handle seal imprints under much fewer constraints. The shape of seals can be a square, an ellipse, a circle, or any close loop. The boundary of the seal imprints is allowed to be imperfect. Furthermore, it is insensitive to the distance between the TV-camera and seal imprints. Experimental results ‡ confirm that the proposed scheme might be feasible for practical applications.

Method of pattern positioning for automatic verification of seal imprint

AbstractIn automatic computer verification of seal imprints accurate positioning of an examined seal imprint over a registered imprint is of great importance. This paper proposes a method which positions an examined seal imprint in relation to a parallel shift and rotation by using the centroid of its frame figure and the pixels on a circle of a certain radius from the centroid. Since this method achieves positioning by using local features of the examined seal imprint, rapid positioning is possible. In the presence of small defects in the imprint frame this method has the advantage that the centroid of the seal imprint is accurately obtained and is not affected by distortion of the imprint frame. In a positioning experiment based on this method 240 actual seal imprints were used. All imprints were positioned within a ±0.1‐mm parallel shift error and more than 99% of the seal imprints were positioned within ±1.76° rotation angle errors. A verification experiment was conducted using a seal imprint verification system which incorporated the principles of this method. As a result, the verification error which was caused by the positioning error was found to be 0.83%. The experimental results show that the proposed positioning method is efficient for automatic verification of seal imprints.