Research On Halftone Images And Information Hiding Technology

As an important step in the image reproduction process,halftone technology is widely used in many fields such as printing and display.For the purpose of protecting the intellectual property rights and source certification of works,it is often necessary to hide some characteristic information in halftone images.Therefore,how to effectively improve the quality of halftone images and use halftone images as carriers to hide information have attracted widespread attention.This article aims to study image halftone technology and its information hiding algorithm,the main research results are as follows:A halftone algorithm with perceived error feedback based on Otsu threshold segmentation(HAPEF-Otsu)is proposed.The error diffusion halftone algorithm is improved by introducing Otsu threshold segmentation and perceived error feedback.The target regions gained from segmentation were used to calculate the visual error,then fed it back to the original grayscale image.The new grayscale image that generated by feedback process needs to through the second error diffusion to obtain the final halftone image.Because halftone images can only be represented by two color values,black and white,a halftone watermarking algorithm with perceived error feedback based on Otsu threshold segmentation(HWAPEF-Otsu)is proposed by inverting pixels to embed watermark in the halftone process.Compared with the traditional error diffusion halftone watermarking algorithm,the halftone images produced by the algorithm have better similarity to the original grayscale images.In objective evaluation indicators,the peak signal-to-noise ratio(PSNR)increased by 0.3?0.4db and the weighted signal-to-noise ratio(WSNR)increased by 1?1.3db.After experiencing the noise attack that caused the most image damage,the normalized correlation(NC)value of the extracted watermark show that HWAPEF-Otsu has better resistance to attack.After analysis,it was found that the halftone images generated by HAPEF-Otsu both have a defect that appears a small area of no ink,it's due to brightness enhancement.So a halftone algorithm with perceived error feedback based on tone partition(HAPEF-TP)is proposed.The algorithm changes the image segmentation method,selects the midtone region based on the image tone partition and Canny edge detection information to calculate the visual error,then feeds the error back to the original grayscale image to generate a new grayscale image.The final halftone images gained by second error diffusion show that the algorithm improved the shortcoming of small no ink area.A halftone watermarking algorithm with perceived error feedback based on tone partition(HWAPEF-TP)through flipping black and white pixels to embed watermark into halftone image.Compared with the traditional error diffusion halftone watermarking algorithm,the PSNR increased by 0.44?0.66 db and the WSNR increased by 0.89?1.4db.It is show that the algorithm maintains good imperceptibility and the robustness of the algorithm is improved by compared with HWAPEF-Otsu.The halftone visual cryptography algorithm with perceived error feedback hides the secret image into two halftone images by modifying the second image halftone process with conjugate concept,the algorithm evaluated by the correct decoding rate(CDR).For the halftone visual cryptography algorithm with perceived error feedback based on Otsu threshold segmentation(HVCPEF-Otsu)and the halftone visual cryptography algorithm with perceived error feedback based on tone partition(HVCPEF-TP),processing the algorithm results separately to extract secret patterns.Under different threshold conditions,the CDR results of HVCPEF-Otsu is 0.7628 and 0.8272 respectively,the CDR results of HVCPEF-TP is 0.7598 and 0.8231 respectively,compared with the highest CDR value of 1.0000,which shows that the two halftone visual cryptography algorithms have good overall performance.The experimental results show that the method of image processing by region with perceived error feedback can achieve the purpose of improving performance of halftone algorithm,and embedding watermarks based on the improved halftone algorithm can also improve the performance of the halftone watermark algorithm.