Research And Application Of Bamboo Script Image Enhancement Algorithm

Bamboo script preserves the rich historical and cultural information. As a writing material in ancient China,Bamboo script is the valuable cultural wealth. Enhancement of the Bamboo script Image is the most key procedure in character reconstruction and text extraction.As most of the Bamboo scripts were buried underground for a very long period,almost all of the Bamboo script the lap over together.They were conglutination and some of them even corrupted.The characters on the Bamboo scripts were fallen off and it is hard to identify. On the other hand,most of the Bamboo script were photoed under poor condition,therefor most of the Bamboo script were in the poor contrast condition. As the dark area in the image includes very importance detail about the character,so the enhancement of the dark area in the Bamboo script is the most useful for archaeologist.In this paper we made the Bamboo scripts from Changsha Jiandu museum as a model and taken the Bamboo script images as our research objects. This paper designs one kind of bamboo scripts images enhancement algorithm according to bamboo scripts image's characteristics and achieves the following specific functional modules:(1)multi-scale Retinex(MSR) algorithmThe Retinex is one kind of image enhancement theory and it eatablished at the scientific experiment and the scientific analysis.It essence is to 'skinning' the illumination in the original image and to yield the reflectance image,that is,the original appearance of the object.Compares with conventional enhancement methods,the Retinex has shown itself to be a very versatile automatic method and can simultaneously provide sharpening,color constancy,dynamic range compression and color rendition. Based on the theory of Retinex, the multi-scale Retinex algorithm is employed to remove the luminance degradation of the Bamboo script image and enhance the dark area and make the Bamboo script more color rendition. (2)gain/offset algorithmUsually after the multi-scale Retinex process,some of the image's Pixels are negative and also will beyond the display's ability,so we need to shift and compress to the display's scope(0-255) .In this paper,the gain/offset algorithm is employed to achieve this aim.(3) contrast stretching algorithmBased on the research of hundred of Bamboo scripts,we made the conclusion that the histogram of the Bamboo scripts usually between 20 to 220.And not take full advantage of all of the gray level(0-255), the image looks very dark and not clear.So in this paper the simple contrast stretching algorithm is deployed to improve the output brightness.The results of experiment show that our algorithm can improve effectively not only the contrast but also can observably enhanced the information of hidden area in the Bamboo script image and provided better tonal rendition. The algorithm can overcome the lack of enhancement of traditional enhancement methods and satisfy the archaeologist's demand.