Recently, new digital screening technologies have been put in practical use with progress of CTP. New digital screening technologies are able to produce an image with a higher apparent resolution and greater detail than conventional halftone screening techniques. The outline and trend of the typical new screening technologies will be introduced in this paper and the comparison with each screening structure will be also shown here. The boundary length of the image area and non-image area in a fixed area, and average distance between dots were measured acording to each technology. I hope this short article will be of some help for you.

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In late 70's when coating system was developed, the first coating system was introduced in 1984 to Japanese market with 4 color sheet-fed press already. In first stage all coating systems were equipped with roller systems. Late'90, there was a development of flexo technology of chamber doctor / anilox roller. And the materials for coating system were improved in the same period. Now the standard feeding system in coating is equipped with a chamber doctor/ anilox roller system and this gives high quality coating results. In the market of Europe and U. S., the utilization of coating is around 80%, but in Asian market it is only 12%. There will be much market development of coating system utilization in Japan in the near future, specially by UV gross coating and metallic coating.

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Printing ink is a kind of printing materials, that is used for making image to substrate, and has to keep printability for each, mimeograph, off set, gravure, flexo, and such-like. In addition, special ink has functions that stimulate five senses of people. So it is called “Functional ink” or “Added-values ink”. It is a good device with high functions, so it will give you a big help. However, it depends on the plan to use it whether you succeed or not. I show it as follows.

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Holograms are now widely seen on credit cards, cash vouchers and so on. Most of these are “embossed-type holograms” which record holographic information by casting a relief pattern on the surface, enabling the mass-replication of the holograms by employing on imposing model. In this paper, hologram technologies for printing appreciation are reviewed, then current status of color hologram fabrication and evaluation methods are also described.

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When proofing spot colors on the direct digital color proof (DDCP), spot colors must be composed of existing DDCP colorants. However, if a spot color is outside the DDCP color gamut, the spot color cannot be reproduced colorimetrically. One of the optimum solutions is to find the perceptually closest color in the gamut using a color difference equation that accurately reflects visual estimates. In this research, five color-difference equations, CIELAB, CMC, BFD, CIE94, and CIEDE2000 were examined. Two types of psychophysical experiments were conducted. The first was a paired-comparison experiment which derived sets of interval scale values. Colordifference values calculated using each equation above were converted into interval color-difference values, and were compared with the interval scale values. The second was a categorical scaling experiment. Evaluation values were derived and compared directly with color-difference values. In addition, the composite-standard method was applied to derive interval scale values in the second experiment. It seemed to estimate perceptual color distances between target and reproduced colors using perceptibility criteria in the paired-comparison experiment and acceptability criteria for the categorical scaling experiment. In both experiments, BFD (1:1) and CIE94 (2:1) indicated the best correlation with the psychophysical evaluations. Additionally, the relationship between color difference values from BFD (1:1) and evaluation values from the categorical scaling experiment were examined to determine the limits of acceptable color difference for practical use.

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Optical dot gain was studied using an image processor and a CCD camera connected to a microscope and a solid patch of a black printed matter. Reflection density traces were measured across the boundary of the solid patch. The density changes drastically around the boundary. The area is roughly consists of three parts, i.e., low density area (density range: d<0.5), middle tone area of which density changes linearly (d=0.5-1.2), and high density area (d>1.2). We measured the width of the middle tone area. The measured width (Δl) decreased with increasing magnitude of an object lens of the microscope. We determined the absolute value (Δl_o) to be 20.5μm by extrapolation of the linear relation between the measured width and reciprocal magnitude (M^-1) of the lens to M^-1=0. Using interference filters, effects of wavelength on the Δl_o value were studied. The widths were determined to be 14.1 (red filter), 18.2 (green filter), and 23.5μm (blue filter).

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There are various press problems ranging from easily recognizable defects such as poor ink lay and tinting to delicate problems such as off tone reproduction. In contrast to paintings created one by one through elaborated printers' works, prints are mass produced by printing process through plate mounting, ink and water feeding on the plate and transferring images on the plate to printing paper. Therefore, changes in every process can emerge as defects of the prints. Complex combination of paper, ink and press conditions can result in press problems. To solve the problems, it is necessary to investigate possible causes step by step.

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