Research On Adaptive Halftone Screening Algorithm Based On Image Content

The halftone screening algorithm converts a continuous-tone image into a binarized image that can be printed out.This algorithm largely determines the quality and effect of reproduction of printed images.With the continuous improvement of printing equipment and computer image processing equipment,the halftone screening algorithm is also constantly evolving.By optimizing the design of the halftone screening algorithm,it has always been the main research content in this field to continuously explore and improve the reproduction effect of continuous tone image print output.This thesis mainly studies a halftone screening algorithm that best matches the continuous tone content.The algorithm is based on common printing process conditions and can better reproduce continuous tone image content(texture details and contours).First,by analyzing several classical halftone screening algorithms and improved algorithms,the output effect and performance characteristics of these algorithms are compared and studied.Secondly,the spectral characteristics of halftone images are compared and analyzed,and an edge-enhanced blue-noise halftone screening algorithm is designed.Aiming at the obvious interference fringes in the halftone images generated by the Floyd-Steinberg error diffusion algorithm,and the prominent loss of image edge detail information,an adaptive halftone screening algorithm based on image content was designed.In order to improve the reproduction effect of the binarized image in the process of image binarization and screening,the algorithm introduces the features of the human visual model,and moderately enhances the edge of the image.Since a certain amount of noise will be introduced in this process,the image is subjected to mean square error modulation processing.At the same time,in order to meet the blue noise characteristics of the image as much as possible,the genetic algorithm is used to obtain the dispersion coefficient of the binarization quantization error,and the halftone screening algorithm is optimized.The effectiveness of the algorithm in this thesis is verified through experimental tests.Based on the traditional error diffusion algorithm,the halftone screen image generated by the algorithm processing has the characteristics of weakening the interference texture and enhancing the edge,showing a better visual effect.