A de-noising method based on L0 gradient minimization and guided filter for ancient Chinese calligraphy works on steles

Feihang Ge,Lifeng He

doi:10.1186/s13640-019-0423-x

Feihang Ge, Lifeng He

Open Access

https://doi.org/10.1186/s13640-019-0423-x

Copy DOI

Abstract

A clear stele image of ancient Chinese calligraphy pieces is very useful for studying ancient Chinese calligraphy. However, due to hundreds of or even thousands of years of natural or artificial damage on stele, images of ancient Chinese stele calligraphy works usually suffer from a large amount of image noise, and which usually leads to a poor visibility. To address this problem, in this paper, we propose a de-noising method based on L0 gradient minimization and guided filter. It consists of two main operations in sequence: First, L0 gradient minimization is utilized to obtain a random-noise free map, and then the random-noise free map is used as a guided image, and convoluted with its corresponding original noised stele image by a guided filter to obtain an edge preserved random-noise free image. Finally, the eight-connection region-based de-noising technique is followed to remove ant-like isolated blocks. Experiments demonstrate that the proposed method is superior to several recent published stele image de-noising techniques in terms of preserving the character structures.

Highlights

Ancient Chinese calligraphy works are very useful for people to learn and study Chinese history and culture [1]
2 Related work Interests regarding image preprocessing, including image de-noising [5] and image enhancement [6], especially on ancient Chinese calligraphy image enhancement [1,2,3,4, 7,8,9,10] have seen increasing in recent years; for instance, Zheng et al [1] presented a de-noising method for stele images using guided filter on the L channel
For the use of guided filter, we employ the random-noise-free map obtained in above section as a guided image and convolute it with the input noised stele image to recover the Chinese character structure in a stele image

Summary

Introduction

Ancient Chinese calligraphy works are very useful for people to learn and study Chinese history and culture [1]. Our contributions in this work are summarized as follows: 1) We put forward a L0 gradient minimization guided image filter for random-noise removal. It consists of two operation steps: First, to smooth a noised stele. 2 Related work Interests regarding image preprocessing, including image de-noising [5] and image enhancement [6], especially on ancient Chinese calligraphy image enhancement [1,2,3,4, 7,8,9,10] have seen increasing in recent years; for instance, Zheng et al [1] presented a de-noising method for stele images using guided filter on the L channel. Motivated by the aforementioned research, in this paper, we employ L0 gradient minimization as well as a guided filter for ancient stele calligraphy image de-noising

Proposed method

Experimental results and discussions

Methods

Conclusions