A GRAY ZONE BETWEEN 2 CLASSES - CASE OF SMOOTH CURVATURE CHANGE

There are many instances in which character shape of a class changes s moothly to that of another class. Although there are many ways of the change, the most delicate change is curvature feature. The paper treat this problem systematically in both theoretically and experimentally. Specifically some confusing pairs were constructed which are well kno wn in the field of OCR, such as 2 <-> Z and 4 <-> 9. A series of sampl es generated using each model which change subtly were provided to con duct a psychological experiment. The results exhibit a monotone change of recognition rates from nearly 100% to 0% as the shape changes cont inuously. To imitate the humans' performance, feature of curvature was extracted based on continuous function representation based on Bezier 's spline curve. Specifically two methods were tried from theoretical and engineering points of view and very successful results were obtain ed.