Use of Gap-Filling Operation to Enhance Image Quality of Binary Image Watermarking

A method for enhancing the image quality of watermarked binary images containing text, drawings, graphs and tables is described. Using the proposed method, we can construct binary watermarking methods that do not perceptually degrade image quality and are robust against image deformation. The method can enhance image quality by accurately detecting the gaps created by the conventional watermarking method and by restoring them at little cost of watermark survivability. Testing of a prototype application demonstrated the validity of the method and revealed that it can widely be used in various binary image watermarking schemes.