Simulation of print quality (PQ) defects is the process of artificially adding structures to an image that when printed will have the appearance of real artifacts. Simulated PQ defects can be used in a variety of types of diagnostic printer documentation, in the development of test pages for PQ defect diagnosis, in the investigation of the perception of PQ defects, and in the development of algorithms for autonomously identifying PQ defects. We develop a general framework for PQ defect simulation, and apply it to the simulation of three different classes of PQ defects associated with color laser printers: defects of uniformity, random marks or repetitive artifacts, and color defects. Each defect is simulated by a geometrical model, or by a scanned sample prototype. The parameters of the model are estimated from actual PQ defect samples. We demonstrate the capability to generate photo-realistic simulations of a total of 9 different defects.
A fundamental investigation was conducted on electrostatic ink jet phenomena. High voltage was applied between an insulative capillary tube filled with ion conductive water and a metal plate electrode. A large water drop was formed and dropped from the tube at the dark discharge under conditions of appropriate voltage application and water level. The diameter of the drop was about one millimeter. At the beginning of corona discharge, however, a Taylor cone of water was formed at the tip of the tube and the tip of the cone was broken to form a very small droplet that was dispersed like mist at wide angle due to the Coulomb repulsive force of charged mist. When the applied voltage was further increased, water droplet was formed periodically. Application of adjusted pulse voltage can form a droplet of which formation is synchronized with the pulse. The diameter of the droplet depended on the applied voltage and the tube diameter. It was less than a Rayleigh's limit and agreed fairly well with a Vonnegut's limit. Preliminary printing on a paper was also demonstrated. This phenomenon is expected to be utilized for a new ink jet print head.
This article presents the experimental photodischarge kinetics and the theoretical investigations of a two-layer organic semiconductor photoreceptor construction that consists of a charge photogeneration layer (CGL) and a hole transport layer (CTL). The experimental results and the theoretical calculations indicate that hole transport in the CTL is significantly influenced by the hole localization in different local energy levels and that these energy levels are at least partly induced by the electric field. The calculated hole localization level density is (0.3 – 1.5)× 1015 cm –3 and the initial hole lifetime relative to localization under the conditions of this investigated, is close to initial transit time T0. The time of hole liberation from a localized state is close to 10 –3 s, exceeding T0 by several times, and therefore the hole localization in the CTL determines the inertness (potential discharge rate) of the photoreceptor.
The title compound is a soluble precursor ("latent pigment": t -BOC DPP) of diketopyrrolopyrrole pigment (DPP) that can be used for electronic and imaging applications in LCD color filters, ink jet and thermal printers. The regeneration and regenerated product of t -BOC DPP have been studied in terms of thermogravimetric and X-ray diffraction analyses, as well as IR and diffuse reflectance spectra on powdered substances. Transformation from t -BOC DPP to the parent DPP begins around 160° C and is completed around 180°C. A variety of colors (yellow via yellowish red to red) appear during the regeneration process, accompanied by evolution of CO2. Further color change also occurs due to aging and dispersion in vehicles. The color as well as the structure of regenerated DPP is slightly different from that of commercial DPP, and the heat and light stability is again not as high as that of the commercial product.
Within color reproduction issues, the reproducible color gamut and color accuracy can be classified as pointwise problems without considering interaction among neighboring pixels. Image color contouring, on the other hand, occurs when perceived local color change exceeds a threshold such that observers perceive unnatural color discontinuity. Therefore, it is the color correlation within neighboring pixels that determines the existence of color contouring artifacts. In this proposal, the objective is to adopt a color flatbed scanner as the measuring device to obtain color as well as spatial information. A set of test targets with smooth geometrical color variation covering various cross sections in the color space is created and printed on different printing systems. Finally, an algorithm to identify the location color contouring is proposed.
In this article, the conditions required for convexity of chromaticity diagrams are discussed. We provide a general formulation of color matching functions that satisfy chromaticity diagram convexity. Using the general formulation, analyses related to shape of color matching functions are performed. The results of this research will contribute to a systematization of color matching functions from a theoretical view point.
Product development activity in the area of ink jet printing papers has accelerated greatly to meet the rapidly growing market for ink jet printing. Advancements in ink jet printing technology have also placed new demands on the paper substrate, due to faster printing rates, greater resolution through decreased drop volumes, and better colorants added to the ink. For glossy ink jet papers, small particle, large surface area fumed silica and aluminum pigments have been shown to provide the desired properties for high quality glossy ink jet coated papers. However, their high cost and low make-down solids in comparison to conventional pigments, has limited their use by the industry to these specialty grades. In previous research, it was seen that the presence of coating cracks increased the micro-roughness of the papers coated with silica based formulations, thereby reducing the gloss of the silica based coatings. Coating cracks were not observed for the alumina coated papers. To minimize the shrinkage of coating layer, coating solids greater than 30% solids should be targeted to reduce the difference between application solids and the coating's immobilization solids point. Since the immobilization solids point is the point at which the free drainage of coating water to the basesheet ceases, raising the application solids will reduce the amount of free water lost to the basesheet upon its application and metering and hence reduce the incidence of cracks. The focus of this study was to determine if the costs can be reduced and application solids could be increased by extending the pigments with less expensive compatible pigments. The effects of the resultant change in packing volume and particle size distribution on the optical properties and printability were determined. It was determined that up to 50 parts of the fumed silica and up to 30 parts of fumed alumina can be replaced with less expensive compatible pigments, without significant loss to the optical and printing properties of the glossy ink jet paper.
Gloss, as has long been known, is a far more complex visual concept than the present methods of instrumental gloss evaluation are able to characterize. The instrumental analyses are either highly over-simplified (standard gloss meters) or over-simplified but with results still difficult to interpret (goniophotometry). The dimensionality and power of the directed reflectance information measured by existing tools is lower and less expressive than the information gained from a direct visual examination of a surface. The purpose of this paper is to review important gloss measurement issues, in the context of perceptual evaluation. This work gives a background for defining necessary requirements for an evaluation system that can reveal the perceptually relevant gloss features of the surface measured.
Gloss, as has long been known, is a far more complex visual concept than the present methods of instrumental gloss evaluation are able to characterize. The instrumental analyses are either highly oversimplified (standard gloss meters) or oversimplified but with results still difficult to interpret (goniophotometry). The dimensionality and power of the directed reflectance information measured by existing tools is lower and less expressive than the information gained from a direct visual examination of a surface. In this article, a new measurement principle for gloss characterization is presented, aimed to give more comprehensive gloss information, which at the same time has an intuitive interpretation. The integrated optical system is compact and has illumination and receptor devices in fixed positions, which facilitates a mechanically simple realization. The instrument is a goniophotometer with a spatial resolution, but it is restricted to a constant angle between the illumination and the receptor. The measurement yields a "Reflectance Vector Map" (RVM) which is an approximate optical equivalent to the surface measured. The RVM simultaneously contains spatially resolved information about directed reflectance and surface apparent inclination. The resolution is high in both spatial and in angular coordinates. The measurement provides a complex massive data set, which when appropriately visualized is similar to the visual properties of the original surface and thus encourages further evaluation and interpretation. A homogeneity index called "Gloss Angle Smoothness" (GAS) is introduced, derived from the RVM, by weighing perceptually "positive" and "negative" components of gloss. The index correlates well with results obtained by a panel of experienced gloss judges asked to rate gloss homogeneity for the limited but demanding set of black printed paper surfaces tested. The GAS index performs considerably better than a panel of inexperienced judges.