Research On Hybrid Screening Algorithm Model And Its Application

Digital screening is a key technique in digital printing,whose purpose is to transfer continuous tone image to halftone image that is used in plate making and printing.The core of digital screening technique is algorithm model,whose quality determines the halftone image quality and finally determines the printing quality.After years of development,digital screening technology has formed relatively intact system.However,the pursuance of printing quality and the fast development of technology lead to the appearance of some problems in single digital screening mode.Some of these problems are hard to be dealt with,which influence the printing effect and quality,even raise the cost of printing.Thus,setting up better Hybrid screening algorithm models is the tendency of digital printing and screening.This paper focuses on the topic and deeply researches Hybrid screening techniques,halftone unit dot algorithm model,hybrid screening models,printing reproduction characteristic of screening algorithm model and Hybrid screening experiment system.Main work and results are as follows.1.Totally conclude the Hybrid screening techniques and bring forward the problems.Conclude and analyze the screening types that form Hybrid screening and problems as well as the research situation of Hybrid screening.Confirm the paper's research aim and content.Conclude the whole research project and process.2.Bring forward and set up halftone unit dot algorithm model,which can settle problems and form hybrid screening model.Firstly,analyze the generation condition of halftone unit dot model and bring forward the algorithm models.Set up HLC screening algorithm model a s well as Moire pattern and line selection model,and finally analyze non-level screen angle HLC algorithm.Set up multiple controllable parameter screening algorithm.Through selecting random number generator and setting up random array model,dot center is confirmed to generate dot.Set up distribution function screening algorithm and pseudo-random function screening algorithm.Use uniform distribution function generator and multiplicative congruence pseudo-random function generator to confirm dot center and exposure dot location.To realize screening under arbitrary condition,current model base method is brought forward.3.Bring forward and set up hybrid screening algorithm model and technique project.On the basis of concluding the problems,according to founded halftone unit dot models,algorithm combination modeling method is set up.Extract image tone information and basic screening information,set up basic selecting model.By selecting information of halftone unit dot model,marching modeling is operated and obtains 4 groups containing 16 types of hybrid screening algorithm models.Three impact factors of transition zone smooth model,dot critical model and extreme high tone dot merger model are brought forward and set up shift algorithm model of gradual change center,dot reconstruction algorithm model under same grey level and dot merger algorithm model.Finally,conclude other hybrid screening algorithms and methods.4.Carry out quality evaluation and validation of screening algorithms and get printing reproduction characteristic.Evaluate halftone unit dot model,which includes halftone image and inner structure evaluation,halftone reconstruction accuracy evaluation and halftone image entropy difference evaluation.According to the done experiment,simulation model of screening algorithm reproduction characteristic is set up,through which the feasible zone of reproduction characteristic curve is brought forward.Through experiment under the same printing condition,plate reproduction characteristic curve,paper reproduction characteristic curve and dot gain compensation curve are obtained.Screening algorithm's reproduction characteristic is analyzed.And then study the printing effect of hybrid screening printing images and do subjective evaluation on halftone images.According to the evaluation results,feasible printing and screening project is brought forward.5.Design and develop Hybrid screening experiment system.According to the halftone unit dot model and hybrid screening model,design and develop Hybrid screening experiment system,which includes image processing interface,halftone unit screening processing interface and hybrid screening processing interface.This system can realize screening through the algorithm models raised in the paper and generate halftone image to make experiment plate and printing.