In order to solve the problem that the seals are difficult to extract accurately from the Chinese calligraphy works

an algorithm for extraction of seals based on Guide-filter is proposed. This algorithm makes full use of advantage that Guide-filter can preserve the edges of the images

and can approximate the objects greatly.The residual image between binary images obtained by the double threshold values method is used as the input image of Guide-filter

and the original image as guiding image

finally

accurate seal image can be obtained.Besides

the edge density is used to evaluate the effect of seal extraction objectively. The experiment results show that the proposed algorithm can extract the seals information better.