Research On Halftone Watermarking Algorithm

Digital watermarking technology,as an important means of copyright protection and identity authentication of digital products,has received more and more attention in recent years.This paper focuses on the extensive application of halftone watermarking algorithms in halftone images used in printing.According to the existing halftone watermarking algorithm,three kinds of halftone watermarking algorithms applied in different aspects are proposed.The specific contents are as follows:(1)A proposed amplitude modulation halftone watermarking algorithm based on raster detection copying is proposed.The traditional amplitude-modulated halftone watermarking algorithm based on raster detection uses a halftone dot shape as a concentrated shape.The dot of this shape is not easily distorted during the printing and copying process,and the watermark embedded by the method of moving the halftone dot as a whole is not easily distorted during the printing and copying process.The watermark that can be detected in the original print can also be detected in the copy.In order to ensure the uniqueness of the original printing,this paper modifies the dot of the amplitude-modulated halftone watermarking algorithm based on raster detection,so that the amplitude-modulated halftone watermark based on raster detection is more likely to be lost during copying,making the watermark vulnerable to copying.(2)A visual cryptography algorithm that can be applied to direct binary search for halftone images is proposed.Halftone visual cryptography embeds a binary watermark image hidden into two halftone images.When two halftone images appear alone,the watermark cannot be detected.When two halftone images are overlaid,the watermark image will be revealed.The direct binary search(DBS)halftone algorithm is a halftone algorithm that uses the iterative method to model the halftone of the image by modeling the human visual system.This paper combines visual cryptography with the direct binary search(DBS)human visual system model to successfully apply halftone visual cryptography to halftone images based on direct binary search(DBS).(3)A raster watermarking algorithm that can be used for frequency modulation halftone images is proposed.The amplitude-modulated halftone watermarking algorithm based on raster detection needs to cover the watermark traces by Moire effect,and can only be applied to color images.In this paper,the principle of halftone watermarking for raster detection is applied to the frequency modulation halftone algorithm.The halftone watermarking algorithm based on raster detection is applied to the gray halftone image,and the half based on raster detection is improved.The visual quality of the carrier halftone image generated by the tone watermarking algorithm.