Based on image processing technology

the contour profile of Chinese red dates is extracted.Polar radius function is used to describe the contour profile

and polar radius function is expanded by Fourier series and the top 15 terms of the series are selected to describe the shape feature of the contour profile.Euclidean distance and irregularity degree discrimination method are applied to recognize the shape of red dates respectively

and experimental results indicate that the two methods have high accuracy of recognition on normal red dates

on malformation ones

the recognition rate of Euclidean distance is only 35 % and that of irregularity degree method can reach 90 %.