Color Reproduction of Metallic-Ink Images

We study the color reproduction of full-color metallic-ink images. Full-color metallic-ink images are prints whose contributing colorants are exclusively made of colored metallic inks. Due to the presence of metallic particles, metallic inks show a metal-like luster. These particles are opaque and hide the underlying ink or substrate. In order to obtain predictable halftone colors, we need a juxtaposed halftoning method to create halftone dots of different colors side by side without overlapping. Juxtaposed halftoning invalidates many assumptions generally made for the color reproduction workflow. For printing metallic-ink images, one needs a color separation system creating surface coverages for the 8 metallic inks that correspond to the 8 Neugebauer primaries. For this purpose, we introduce a simple and fast method for N-color separation that relies either on Demichel’s or on a variant of Kueppers’ ink-to-colorant separations. Thanks to a unique set of ink-to-colorant formulas, pseudo-CMY ink values are separated into amounts of printable colorants. We also describe color separation procedures that are able to optimize different properties of the resulting metallic-ink images

Modeling and Halftoning for Multichannel Printers: A Spectral Approach

Printing has been has been the major communication medium for many centuries. In the last twenty years, multichannel printing has brought new opportunities and challenges. Beside of extended colour gamut of the multichannel printer, the opportunity was presented to use a multichannel printer for ‘spectral printing’. The aim of spectral printing is typically the same as for colour printing; that is, to match input signal with printing specific ink combinations. In order to control printers so that the combination or mixture of inks results in specific colour or spectra requires a spectral reflectance printer model that estimates reflectance spectra from nominal dot coverage. The printer models have one of the key roles in accurate communication of colour to the printed media. Accordingly, this has been one of the most active research areas in printing. The research direction was toward improvement of the model accuracy, model simplicity and toward minimal resources used by the model in terms of computational power and usage of material. The contribution of the work included in the thesis is also directed toward improvement of the printer models but for the multichannel printing. The thesis is focused primarily on improving existing spectral printer models and developing a new model. In addition, the aim was to develop and implement a multichannel halftoning method which should provide with high image quality. Therefore, the research goals of the thesis were: maximal accuracy of printer models, optimal resource usage and maximal image quality of halftoning and whole spectral reproduction system. Maximal colour accuracy of a model but with the least resources used is achieved by optimizing printer model calibration process. First, estimation of the physical and optical dot gain is performed with newly proposed method and model. Second, a custom training target is estimated using the proposed new method. These two proposed methods and one proposed model were at the same time the means of optimal resource usage, both in computational time and material. The third goal was satisfied with newly proposed halftoning method for multichannel printing. This method also satisfies the goal of optimal computational time but with maintaining high image quality. When applied in spectral reproduction workflow, this halftoning reduces noise induced in an inversion of the printer model. Finally, a case study was conducted on the practical use of multichannel printers and spectral reproduction workflow. In addition to a gamut comparison in colour space, it is shown that otherwise limited reach of spectral printing could potentially be used to simulate spectra and colour of textile fabrics

AN APPRAISAL OF THE DEVELOPMENTS IN THE REPRODUCTION OF COLOUR IN COMPUTER PUBLISHING SYSTEMS

The plethora of coloured images that are reproduced in any printed media is facilitated through a variety of related processes that collectively constitute traditional printing techniques. The aim of this research is to appraise recent developments that have occurred within the colour prepress process. The colour prepress process involves the preparation of colour separated halftone films that are used in the production of offset lithographic printing plates. Over recent years the application of desktop publishing technology to perform many of the functions associated with the colour prepress process has raised a number of significant issues and debates. The reproduction of coloured images in the printed medium demands that certain fundamental criteria are adhered to in order to maintain professional standards of colour fidelity. Such criteria include: successful digital halftone production, the elimination of moiré patterns, and maintaining colour fidelity between the coloured original and the coloured reproduction. This research thesis shall therefore establish the principles and techniques involved in the reproduction of colour in a printed medium. It will also asses whether desktop publishing systems are able to facilitate successful professional colour reproduction by examining current debates that challenge the viability of desktop publishing solutions. Current debates concerning desktop publishing solutions are primarily concerned with assessing the value of Adobe PostScript level 2 solutions, computer interchange spaces for colour matching purposes, and rational supercell techniques that attempt to eliminate moiré patterns. The research also attempts to establish the validity of current debate findings by comparing them with statistics derived hom a questionnaire (undertaken as part of the research program) that seeks the opinions of system users on the effectiveness of their individual systems at processing and delivering acceptable colour separations

Clustered-dot periodic halftone screen design and ICC profile color table compression

This dissertation studies image quality problems associated with rendering images in devices like printing or displaying. It mainly includes two parts: clustered-dot periodic halftone screen design, and color table compression. Screening is a widely used halftoning method. As a consequence of the lower resolution of digital presses and printers, the number of printer-addressable dots or holes in each microcell may be too few to provide the requisite number of tone lev- els between paper white and full colorant coverage. To address this limitation, the microcells can be grouped into supercells. The challenge is then to determine the desired supercell shape and the order in which dots are added to the microcell. Using DBS to determine this order results in a very homogeneous halftone pattern. To simplify the design and implementation of supercell halftone screens, it is common to repeat the supercell to yield a periodically repeating rectangular block called the basic screen block (BSB). While applying DBS to design a dot-cluster growth order- ing for the entire BSB is simpler to implement than is the application of DBS to the single non-rectangular supercell, it is computationally very inefficient. To achieve a more efficient way to apply DBS to determine the microcell sequence, we describe a procedure for design of high-quality regular screens using the non-rectangular super- cell. A novel concept the Elementary Periodicity Set is proposed to characterize how a supercell is developed. After a supercell is set, we use DBS to determine the micro-cell sequence within the supercell. We derive the DBS equations for this situation, and show that it is more efficient to implement. Then, we mainly focus on the regular and irregular screen design. With digital printing systems, the achievable screen angles and frequencies are limited by the finite addressability of the marking engine. In order for such screens to generate dot clusters in which each cluster is identical, the elements of the periodicity matrix must be integer-valued, when expressed in units of printer-addressable pixels. Good approximation of the screen sets result in better printing quality. So to achieve a better approximation to the screen sets used for commercial offset printing, irregular screens can be used. With an irregular screen, the elements of the periodicity matrix are rational numbers. In this section, first we propose a procedure to generate regular screens starting from midtone level. And then we describe a procedure for design of high-quality irregular screens based on the regular screen design method. We then propose an algorithm to determine how to add dots from midtone to shadow and how to remove dots from midtone to highlight. We present experimental results illustrating the quality of the halftones resulting from our design procedure by comparing images halftoned with irregular screens using our approach and a template-based approach. We also present the evaluation of the smoothness and improvement of the proposed methods. In the next part, we study another quality problem: ICC profile color table compression. ICC profiles are widely used to provide transformations between different color spaces in different devices. The color look-up tables (CLUTs) in the profiles will increase the file sizes when embedded in color documents. In this chapter, we discuss compression methods that decrease the storage cost of the CLUTs. For DCT compression method, a compressed color table includes quantized DCT coefficients for the color table, the additional nodes with large color difference, and the coefficients bit assignment table. For wavelet-based compression method, a compressed color table includes output of the wavelet encoding method, and the additional nodes with large color difference. These methods support lossy table compression to minimize the network traffic and delay, and also achieves relatively small maximum color difference

Spectral printing of paintings using a seven-color digital press

The human visual system is trichromatic and therefore reduces higher dimensional spectral data to three dimensions. Two stimuli with different spectral power curve shapes can result in the same cone response and therefore match each other. Color reproduction systems take advantage of this effect and match color by creating the same cone response as the original but with different colorants. ICC color management transforms all colors into a three-dimensional reference color space, which is independent from any input or output devices. This concept works well for a single defined observer and illumination conditions, but in practice, it is not possible to control viewing conditions leading to severe color mismatches, particularly for paintings. Paintings pose unique challenges because of the large variety of available colorants resulting in a very large color gamut and considerable spectral variability. This research explored spectral color reproduction using a seven-color electrophotographic printing process, the HP Indigo 7000. Because of the restriction to seven inks from the 12 basic inks supplied with the press, the research identified both the optimal seven inks and a set of eight artist paints which can be spectrally reproduced. The set of inks was Cyan, Magenta, Yellow, Black, Reflex Blue, Violet and Orange. The eight paints were Cadmium Red Medium, Cadmium Orange, Cadmium Yellow Light, Dioxazine Purple, Phthalo Blue Green Shade, Ultramarine Blue, Quinacridone Crimson and Carbon Black. The selection was based on both theoretical and experimental analyses. The final testing was computational indicating the possibility of both spectral and colorimetric color reproduction of paintings

Tattooed Skin and Health

With about 10–20% of the adult population in Europe being tattooed, there is a strong demand for publications discussing the various issues related to tattooed skin and health. Until now, only a few scientific studies on tattooing have been published. This book discusses different aspects of the various medical risks associated with tattoos, such as allergic reactions from red tattoos, papulo-nodular reactions from black tattoos as well as technical and psycho-social complications, in addition to bacterial and viral infections. Further sections are dedicated to the composition of tattoo inks, and a case is made for the urgent introduction of national and international regulations. Distinguished authors, all specialists in their particular fields, have contributed to this publication which provides a comprehensive view of the health implications associated with tattooing

The Role of Standardization in Specialization of Ceramic Production at San Marcos Pueblo, New Mexico

In my dissertation research, I examine decorated pottery production at San Marcos Pueblo, in the Galisteo Basin of north central New Mexico. San Marcos Pueblo was occupied from A.D. 1250 until the Pueblo Revolt against the Spanish in 1680. In previous research, San Marcos Pueblo was suggested to be a production center for Northern Rio Grande Glaze Wares (Glaze Ware) (Warren 1976, 1979). I evaluate this claim by examining over 700 pottery sherds and whole vessels from the site and surrounding region. In addition, I examine how pottery production at San Marcos was organized and how this structure changed through time. I examined attributes of the pottery using electron microprobe, petrographic, and attribute analyses to determine local production and degree of standardization of production throughout the occupational sequence at the site. Production specialization, defined as production over the needs of the household (Costin 2001), has been tied to product standardization. Standardization, reduction in variability of an assemblage, has thus been used as an indicator of specialization of ceramic production in archaeological contexts (Benco 1988; Costin 1991; Hagstrum 1985). However, its validity as an indicator of specialized production has been tested only in modern ethnographic contexts and with varying results (e.g., Benco 1988; London 1991; Longacre 1999; Roux 2003; Stark 1995). Within the Northern Rio Grande region of the Southwest, glaze-paint ceramics were produced from A.D. 1315 to 1700. Evidence suggestive of specialization in ceramic production in the Galisteo Basin is found in the glaze-paint ceramics made with latite or monzonite temper (a material found in and along the margins of the Galisteo Basin) occurring in ceramic assemblages from sites outside of the basin (Shepard 1942, 1965; Warren 1969, 1976, 1979). The widespread distribution is indicative of some level of specialized production in the Galisteo Basin, and specifically at San Marcos Pueblo. One important component of the organization of production is intensity, defined as the number of goods produced in a given unit of time (Costin 1991, 2001). High intensity of production is also frequently equated with standardization, assuming that the more time producers spend making pots (the higher the intensity of production), the more standardized their products become (Rice 1992). Previous researchers (Shepard 1942, 1965; Warren 1976, 1979) have argued that Glaze Ware production intensified from approximately A.D. 1400 to 1500, then decreased until the time this pottery was no longer produced. My dissertation research evaluates, first, the extent of production for local use and export at San Marcos, and second, the changes in the level of standardization throughout the production of Glaze Wares at the site. My dissertation results suggest that San Marcos Pueblo potters made more pottery than was used at the site and exported pots to sites throughout the Rio Grande Valley. In addition, the assemblage of pots at San Marcos is over 80% locally made, with the proportion rising to almost 100% during some of the most intense periods of production. These results support earlier suggestions of specialized production of pottery at the site. The findings for standardization are intriguing, as there are almost no changes in the level of standardization through time. These results indicate that the production system was incredibly stable, even with other major changes in the lives of the potters, including Spanish contact and the establishment of a Spanish mission at the site. In addition, my research at San Marcos suggests that there is not a direct relationship between intensity of production and standardization of the assemblage produced, at least at the low level of specialized production practiced at San Marcos

Design, graphic arts, and environment

The environment draws great attention today from many people and businesses. Some companies are beginning to play off these concerns in their marketing approach, while others dodge the topic at all turns. While many people feel we have serious environmental problems, others do not. It is a subject with which everyone is, perhaps, too hasty in their judgment. This thesis project encourages behavioral awareness and provides information from a multitude of sources so that a practical, rather than radical, view may develop. Information surrounding issues about the environment appear in many diverse publications. The sources of information, as well as the information itself, are very broad. This thesis project, Design, Graphic Arts, and the Environ ment, brings a great number of these sources together. The proposed publication discusses many different topics. More detailed information, if desired by the reader, may be found by consulting the extensive list of references supplied. This project focuses on environmental issues from the standpoint of a designer, graphic artist, or printer. These people, while often restricted by a client, make many decisions affecting the environment. They must realize their pivotal position between industry and customers, and between technical and marketing people. They must use their knowledge and position of influence for the benefit of all, including the environment. This project covers six main topics. Part One addresses paper, focusing on recycled papers and environmental labeling organizations. Part Two, Bleaching, looks at the needs, methods and effects of this paper unit operation. Part Three discusses printing inks and the concern of pigments and oils used in their com position. Part Four then investigates de-inking methods and the problems associated with them. Packaging, Part Five, describes the function of this indus try and analyzes some packaging materials being used. Lastly, Standards & Regulations, Part Six, looks at the government\u27s role in environmental issues. An appendix follows with organizations to contact for further information. An addi tional appendix includes two sample issues of the proposed publication. The thesis project presents information about varied, yet related topics, in the hopes of generating environmental interest in readers. People are encour aged to read further about a specific subject; this thesis is not meant to provide solutions, but rather information. The condition of the environment is an enormous and critical topic that has the potential to affect everyone. When people sense that their behavior can have an impact, albeit small, on a large problem, they can and often do change their behavior. Ideally, everyone should consider their environment in their daily decision mak ing. For persons working in the design, graphic arts and printing industries, this thesis project provides the type of information, or access to it, needed to make those decisions