engleski

Dot Gain Evaluation by Changing Dot Shapes and Screen Ruling on Prints Defined Outside of Offset Standard

One of the most important factors that affect a colored reproduction in offset printing is the choice of screen elements. They directly affect the realization of light, medium and dark tones of the image. Due to changes to the output LUT curves of CTP device comes to signif-icant deviations and they are not the same for all dot shapes. In this work will be compared and discussed how different geometric shapes of the screen elements (line, rhomboid, circle) and differently defined screen ruling (133lpi, 175lpi for AM raster and 20μm, 35μm for FM Staccato raster) affects the final dot gain. By densitometric measurements will be measured inking density and by using the Murray-Davies equation calculated the coverage area on the basis of which will be determined de-viation of dot gain. Based on the results, curves will be created to determine the correction parameters for every dot shape. This will give the recommendation which dot shape and screen ruling is stable for offset printing on fine art paper.

offset printing; dot gain; screen ruling; dot shapes

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