A circular seal registration method by transforming the round region into rectangular region

At present, the registration of the circular seal is complex and not precise enough. This paper proposes a method for seal alignment by turning a circular seal to a rectangular seal. This method can make the registration process simple. First, this method transforms seal images from two-dimensional data into one-dimensional data. Therefore the circular seal along the radius of the image is spread out into a rectangular form and the rectangular image of this seal can be obtained. Second, longitudinal one-dimensional projection of the rectangular image is performed. Finally, the deflection angle between the reserved seal and the tested seal is obtained by calculating the difference between the one-dimensional projections of the reserved seal and the tested seal with 2 π being the circle. The experimental results show that this method obtained highly accuracy results compared with the traditional method.