Degraded Document Image Binarization Techniques

Document Image Binarization is performed in the preprocessing stage for document analysis and it aims to segment the foreground text from the document background. A fast and accurate document image binarization technique is important for the ensuing document image processing tasks such as optical character recognition (OCR) and Document Image Retrieval (DIR). This research area has been studied for decades; many techniques have been reported and applied on different commercial document analysis applications. However, there are still some unsolved problems need to be addressed due to the high inter/intra-variation between the text stroke and the document background across different document images. Image binarization is the method of separation of pixel values into dual collections, black as foreground and white as background. Thresholding has found to be a well-known technique used for binarization of document images. Thresholding is further divide into the global and local thresholding techniques.