The new otsu thresholding for binarization of the ancient copper inscriptions

This paper offers a new approach for the binarization of the Ancient Copper Inscription. The homogeneous color on this inscription requires a different method for the binarization process. This kind of document differs from documents on paper media written with ink because the characters on the inscription have been carved. The new Otsu thresholding combines the feature of Gray Level Co-occurrence Matrix (GLCM) and Otsu Thresholding. GLCM is used for the texture extraction of the image. The texture, consisting in a pattern of color intensity, is used to strengthen the difference between text inscription and inscription plate, to simplify the binarization process. Sliding window is used to take every part of the image to be extracted. Texture extraction process is conducted in CIE Lab color space using GLCM method. The result of texture feature extraction is converted into a grayscale image then binarized using Otsu method. By the evaluation of such binarization, the values are as follows: 95.4% for F-measure, 94.44% for Pseudo F-measure, 11.15 for PSNR and 37.82 for DRD. These values are better than all the comparison methods, demonstrating that Otsu method is suitable for being used.