Study On Halftone Screen Algorithm And Screen Dots Anti-replication Properties

One of the core technologies of digital printing,digital halftoning is a bridge for the digital conversion between the original manuscript and printing.Due to its low cost,simple operation,and space-saving advantages,digital halftoning has been widely used in various fields closely related to people,such as printing,anti-counterfeiting,watermarking,information encryption,and image transmission.Currently,there are several problems with digital halftone technology,such as large-scale use of traditional square,circular,and other basic dot shapes as printing dots;small dots are prone to loss,affecting the printing quality of the entire image;current algorithms can only output fixed resolutions,and cannot be precisely matched with actual printing machines.Furthermore,with the country’s strong emphasis on green ecology,higher requirements have been proposed for anti-counterfeiting technologies that rely on large amounts of special materials.As one of the core technologies in anti-counterfeiting,halftone technology should also vigorously develop low-cost and green anti-counterfeiting methods.Research on digital halftoning still has very important research value.The main contributions of this thesis are as follows:(1)This thesis proposes a gravure halftone algorithm.Firstly,a special dot model with shapes such as hexagonal and fish scale can be established through mathematical modeling,and the best effect can be achieved through a certain arrangement.Then,the dot decomposition and assignment algorithm is designed to obtain the dot generation model,which ensures good dot grid retention.Based on the resolution and size,the pixel mapping formula between the input image and the output image is established.The experiment proves that a more beautiful visual experience can be obtained on a microscopic level and better image printing quality and effect can be achieved on a macroscopic level.(2)Based on the error diffusion halftone algorithm,dots smaller than a certain threshold can be dispersed to eliminate the effect of small dots.However,due to the limitations of the error diffusion algorithm and the serious texture it brings the worm phenomenon of halftone images can be reduced by optimizing the error diffusion and dynamically distributing the seed points of the dot center.(3)Based on amplitude and frequency modulation halftone technology,the antireplication property of dots can be studied.The document anti-replication effect can be achieved only by relying on the size and arrangement of dots.The experiment proves that the difference of dots in printed images is visually invisible at a resolution of600 dpi,but the anticounterfeiting information can be clearly seen in copied documents,and it can be used in multiple gray levels,increasing the applicability range.This research achieves good anti-counterfeiting performance with only low-cost,green ordinary ink and special halftone algorithms.