Search

The process of conventional 3D printing begins by first build a 3D model, then convert to the model to G-code via a slicer software, feed the G-code to the printer, and finally start the printing. The most simple and popular 3D printing technique is Fused Deposition Modeling. However, in this method, the printing path that the printer head can take is restricted by the G-code. Therefore the printed 3D models with complex pattern have structural errors like holes or gaps between the printed material lines. In addition, the structural density and the material’s position of the printed model are difficult to control. We realized the G-code editing, Fabrix, for making a more precise and functional printed model with both single and multiple material. The models with different stiffness are fabricated by the controlling the printing density of the filament materials with our method. In addition, the multi-material 3D printing has a possibility to expand the physical properties by the material combination and its G-code editing. These results show the new printing method to provide more creative and functional 3D printing techniques.

This paper presents a space mission enablement and cost reduction technology: in-space 3D printing. Using in-space 3D printing, spacecraft can be lighter, require less launch volume and be designed solely for orbital operations. The proposed technology, which supports various thermoplastics and prospectively metals, is presented in detail. Key subsystems such as the energy collection system, the melting unit, and the printing unit are explained.

Gravure printing is a very promising method for printed electronics because it combines high throughput with high resolution. Recently, printed lines with 2μm resolution have been demonstrated at printing speeds on the order of 1m/s. Here we build on these results to study how more complex patterns can be printed that will ultimately lead to printed circuits. We study how the drag-out effect leads to proximity effects in gravure when multiple lines are printed close to each other. Drag-out occurs as the doctor blade passes over the roll surface to remove excess ink from the land areas in between the cells that make up the pattern. In addition to this desirable removal of excess ink, some ink from the cells also wicks up the doctor blade and is removed from the cells. This ink is subsequently deposited on the land area behind the cells leading to characteristic drag-out tails. If multiple lines, oriented perpendicular to the print direction, are printed close to each other, the ink that has wicked up the doctor blade from the first line will affect the drag-out process for subsequent lines. Here we show how this effect can be used to enhance print quality of lines as well as how it can deteriorate print quality. Important variables that will determine the regime for printing optimization are ink viscosity, printing speed, cell size, cell spacing and relative placement of lines. Considering these factors carefully allows one to determine design rules for optimal printing results.

This paper presents the experimental design and initial testing of a system to characterize the progress and performance of a 3D printer. The system is based on five Raspberry Pi single-board computers. It collects images of the 3D printed object, which are compared to an ideal model. The system, while suitable for printers of all sizes, can potentially be produced at a sufficiently low cost to allow its incorporation into consumer-grade printers. The efficacy and accuracy of this system is presented and discussed. The paper concludes with a discussion of the benefits of being able to characterize 3D printer performance.

With the recent introduction of mobile devices and development in client side application technologies, there is an explosion of the parameter matrix for color management: hardware platform (computer vs. mobile), operating system (Windows, Mac OS, Android, iOS), client application (Flesh, IE, Firefox, Safari, Chrome), and file format (JPEG, TIFF, PDF of various versions). In a modern digital print shop, multiple print solutions are used: digital presses, wide format inkjet, dye sublimation inkjet are used to produce a wide variety of customizable products from photo book, personalized greeting card, canvas, mobile phone case and more. In this paper, we outline a strategy spans from client side application, print file construction, to color setup on printer to manage consistency and also achieve what-you-see-is-what-you-get for customers who are using a wide variety of technologies in viewing and ordering product.

This paper examines the transferability of the Munsell system to modern inkjet colorants and printing technology following a similar approach to his original methods. While extensive research and development has gone into establishing methods for measuring and modelling the modern colour gamut, this study seeks to reintegrate the psychophysical and artistic principles used in Munsell’s early colour studies with digital print. Contemporary inkjet printing, with ink sets containing a greater number of primary colorants, are significantly higher in chroma compared to the limited colorants available at the time of Munsell’s original work. Following Munsell’s design and implementation, our experiments replicate the use of Clerk-Maxwell’s spinning disks in order to examine the effects of colour mixing with these expanded colour capacities, and to determine hue distribution and placement. This work revisits Munsell's project in light of known issues, and formulates questions about how we can reintegrate Munsell's approach for colour description and mixing into modern colour science, understanding, and potential application.

With the emergence of high-end digital printing technologies, it is of interest to analyze the nature and causes of image graininess in order to understand the factors that prevent high-end digital presses from achieving the same print quality as commercial offset presses. In this paper, we report on a study to understand the relationship between image graininess and halftone technology. With high-end digital printing technology, irregular screens can be considered since they can achieve a better approximation to the screen sets used for commercial offset presses. This is due to the fact that the elements of the periodicity matrix of an irregular screen are rational numbers, rather than integers, which would be the case for a regular screen. To understand how image graininess relates to the halftoning technology, we recently performed a Fourier-based analysis of regular and irregular periodic, clustered-dot halftone textures. From the analytical results, we showed that irregular halftone textures generate new frequency components near the spectrum origin; and that these frequency components are low enough to be visible to the human viewer, and to be perceived as a lack of smoothness. In this paper, given a set of target irrational screen periodicity matrices, we describe a process, based on this Fourier analysis, for finding the best realizable screen set. We demonstrate the efficacy of our method with a number of experimental results.

The cost and scope of additive printing machines range from several hundred to hundreds of thousands of dollars. For the extra money, one can get improvements in build size, selection of material properties, resolution, and consistency. However, temperature control during build and fusing predicts outcome and protects the IP by large high cost machines. Support material options determine geometries that can be accomplished which drives cost and complexity of printing heads. Historically, 3D printers have been used for design and prototyping efforts. Recent advances and cost reduction sparked new interest in developing printed products and consumables such as NASA who is printing food, printing consumer parts (e.g. cell phone cases, novelty toys), making tools and fixtures in manufacturing, and recursively print a self-similar printer (c.f. makerbot). There is a near term promise of the capability to print on demand products at the home or office... directly from the printer to use.

In this paper we propose an automated solution that compensates for CMYK inkjet printer output non-uniformities. The solution is applied to a printer employing fixed printhead arrays. The algorithm initially pre-processes scanned image of printed output to isolate the desired region of interest. The region of interest information is utilized to extract non-uniformities across the entire printed area. Finally, the algorithm concludes in a calibration step that enables compensation of the identified non-uniformities and provides the desired tonal target response.

Current research at the Centre for Fine Print Research (CFPR) at the University of the West of England, Bristol, is exploring the potential of creating coloured pictorial imagery from a continuous tone relief surface. To create the printing matrices the research team have been using CNC milled images where the height of the relief image is dictated by creating a tone curve and then milling this curve into a series of relief blocks from which the image is cast in a silicone ink. A translucent image is cast from each of the colour matrices and each colour is assembled - one on top of another - resulting is a colour continuous tone print, where colour tone is created by physical depth of colour. This process is a contemporary method of continuous tone colour printing based upon the Nineteenth Century black and white printing process of Woodburytype as developed by Walter Bentley Woodbury in 1865. Woodburytype is the only true continuous tone printing process invented, and although its delicate and subtle surfaces surpassed all other printing methods at the time. The process died out in the late nineteenth century as more expedient and cost effective methods of printing prevailed. New research at CFPR builds upon previous research that combines 19th Century Photomechanical techniques with digital technology to reappraise the potential of these processes.

In many halftoning applications there is a need to generate a dispersed pattern of dots that is pleasing to the eye. We propose a method based on Riesz energy minimization that produces superior patterns than other techniques such as Direct Binary Search and k-means. We illustrate the proposed technique and discuss implementation issues including nonlinear programming techniques and memory-constrained implementations.

With digital printing systems, the achievable screen angles and frequencies are limited by the finite address- ability 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. 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 paper, we describe a procedure for design of high-quality irregular screens. We start with the design of the midtone halftone pattern. We then propose an algorithm to determine how to add dots from midtone to shadow and how to remove dots from mid-tone 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. Publisher’s Note: The first printing of this volume was completed prior to the SPIE Digital Library publication and this paper has since been replaced with a corrected/revised version.

Inkjet printing is a digital printing technique that is capable of depositing not only inks, but functional materials onto different substrates in an additive way. In this paper, applications of inkjet printed structures for microfluidic lab-on-chip systems are discussed. Such systems are promising for different chemical or biochemical analysis tasks carried out at the Point-of-Care level and therefore due to cost reasons are often fabricated from polymers. The paper discusses inkjetprinted wiring structures and electroactive polymer (EAP) actuators for use in microfluidic lab-on-chip systems. Silver and gold wirings are shown that are fabricated by printing metal nanoparticle inks onto polymer substrates. After printing the structures are sintered using argon plasma sintering, a low-temperature sintering process that is compatible with polymer substrates. The wirings consist of several electrode like structures and contact pads and feature minimum structure sizes of approximately 70 μm. They can be used for electrodes, fluid presence detectors and localized ohmic heaters in lab-on-chip systems. Based on that an all inkjet-printed EAP actuator then is discussed. Membrane-type bending actuators generate deflections of approximately 5 μm when being driven at a resonance frequency of 1.8 kHz with 110 V. Derived from that and assuming passive valves on-chip pumping rates in the range of 0.5 ml/min can be estimated.

Saving of toner/ink consumption is an important task in modern printing devices. It has a positive ecological and social impact. We propose technique for converting print-job pictures to a recognizable and pleasant color sketches. Drawing a "pencil sketch" from a photo relates to a special area in image processing and computer graphics - non-photorealistic rendering. We describe a new approach for automatic sketch generation which allows to create well-recognizable sketches and to preserve partly colors of the initial picture. Our sketches contain significantly less color dots then initial images and this helps to save toner/ink. Our bio-inspired approach is based on sophisticated edge detection technique for a mask creation and multiplication of source image with increased contrast by this mask. To construct the mask we use DoG edge detection, which is a result of blending of initial image with its blurred copy through the alpha-channel, which is created from Saliency Map according to Pre-attentive Human Vision model. Measurement of percentage of saved toner and user study proves effectiveness of proposed technique for toner saving in eco-friendly printing mode.

The current inkjet market is mainly composed of two dimensional printers, paper and vinyl printing, 3D CAD, solvent wide-format and UV printing onto paper, plastics and board. Inkjet is ubiquitously used as a proofing or prototyping tool in preparation for print production, but it is also being used as the means to print final products and artefacts, for example, printing onto wallpaper, hot-air balloon nylon and furniture. This has been made possible through the more permanent and enduring UV curable inks. In order to increase density of colour and improve ink coverage when printing onto a range of surfaces, this paper will present research into over-layering of colour and the appearance of colour at 'n' levels of ink coverage. It will also present a study into layering of greys and gloss in order to improve the appearance of printed images onto metal. Returning to our original investigation of artist's requirements when making inkjet prints (1999-), these observations are based on empirical approaches that address the need to present physical data that is more useful and meaningful to the designer. The study has used colour charts to measure colour to provide users with apriori understanding at a soft-preview level and printed colour circles to demonstrate the appearance of printed colour on different substrates. Test results relating to the appearance of print on different surfaces, and a series of case studies will be presented. Dr Carinna Parraman is a member of the Program Committee for the Electronic Imaging Science and Technology Conference, Color Imaging XVII: Displaying, Processing, Hardcopy, and Applications Panel, 24 - 26 January 2012, San Francisco, USA.

There are several parameters, which influence the characteristics of the final printed colors in digital printing. One of the most important one is the substrate (paper). In the present study, the effect of uncoated papers on the laser printed colors was investigated. For this purpose, three kinds of paper with the same grammage value of 80 and different whiteness and texture were selected. The effect of paper on the printer's reproducibility, light-fastness, color gamut and colorimetric characteristics of the final printed samples were studied for a Canon Laser Printer LBP-5050. It was found out that, the reproducibility of the printer is statistically dependent on the paper's type. The average of color change via exposing light is between 1.3 and 1.8 for different papers. The color difference caused by paper variation illustrates the effect of paper on the final printed colors. The texture properties of the papers were quantified with Edge Frequency technique as an appropriate texture analysis tool. A defined correlation between texture changes and color differences was obtained. Furthermore, the whiteness of the papers clearly affected the final printed colors.

Except for linear devices like CRTs, color transformations from colorimetric specifications to device coordinates are mostly obtained by measuring a set of samples, inverting the table, and looking up values in the table (including interpolation), and mapping the gamut from input to output device. The accuracy of a transformation is determined by reproducing a second set of samples and measuring the reproduction errors. Accuracy as the average predicted perceptual error is then used as a metric for quality. Accuracy and precision are important metrics in commercial print because a print service provider can charge a higher price for more accurate color, or can widen his tolerances when customers prefer cheap prints. The disadvantage of determining tolerances through averaging perceptual errors is that the colors in the sample sets are independent and this is not necessarily a good correlate of print quality as determined through psychophysics studies. Indeed, images consist of color palettes and the main quality factor is not color fidelity but color integrity. For example, if the divergence of the field of error vectors is zero, color constancy is likely to take over and humans will perceive the color reproduction as being of good quality, even if the average error is relatively large. However, if the errors are small but in random directions, the perceived image quality is poor because the relation among colors is altered. We propose a standard practice to determine tolerance based on the Farnsworth-Munsell 100-hue test (FM-100) for the second set and to evaluate the color transpositions—a metric for color integrity—instead of the color differences. The quality metric is then the FM-100 score. There are industry standards for the tolerances of color judges, and the same tolerances and classification can be use for print workflows or its components (e.g., presses, proofers, displays). We generalize this practice to arbitrary perceptually uniform scales tailored to specific applications and present an implementation. In essence, we propose to extend the color discrimination test procedures used to evaluate human observers, to mechanical and electronic color reproduction devices.

Periodic clustered-dot screens are widely used for electrophotographic printers due to their print stability. However, moir´e is a ubiquitous problem that arises in color printing due to the beating together of the clustered-dot, periodic halftone patterns that are used to represent different colorants. This beating or interference phenomenon introduces spurious low frequency (large period) patterns in the printed output that are very objectionable to the viewer. The traditional solution in the graphic arts and printing industry is to rotate identical square screens to angles that are maximally separated from each other. For example, the classic three-color screen set rotates three identical square screens to the angles 15°, 45°, and 75°, respectively. However, the effectiveness of this approach is limited when printing with more than four colorants, i.e. N-color printing, where N >4. Moreover, accurately achieving the angles that have maximum angular separation requires a very high resolution plate writer, as is used in commercial offset printing. In this paper, we propose a systematic way to design color screen sets for periodic, clustered-dot screens that offers more explicit control of the moir´e properties of the resulting screens when used in color printing. We find a general concept for moir´e-free screen design that is called lattice-based screen design. The basic concept behind our approach is the creation of the screen set on a 2-dimensional lattice in the frequency domain and then picking each fundamental frequency vector of the individual colorant planes in the created spectral lattice according to the desired properties. The halftone geometry of a screen set is the set of angles and frequencies in units of lines per inch (LPI) of each screen plane. The lattice-based screen design offers more flexibility in designing N-color screen sets with different halftone geometries, and all of them are guaranteed to be all-orders moir´e-free. For example, by creating a square lattice in the frequency domain, square N-color moir´e-free screen sets that consist of N rotated square screens can be achieved. The proposed approach maintains the advantage of square clustered-dot screen design and is based on low addressability of digital printing. We also propose several symmetry measures, and use them to compare the proposed 4-color square screen set and the screen sets based on a previous moir´e-free N-color non-orthogonal approach. The proposed screen set is shown to have better symmetry properties.

Current printing technologies enable customers to reproduce high quality, realistic, and colorful hard copies of their digital documents. Although the activity of printing is transparent to the customers, the progression of a customer's document through the color printing workflow (CPW) is a complex process that may alter the colors in the print job. Given the complexity of the CPW, it is a difficult problem to diagnose the source of the color issue. Novel tools and methods that address this challenge are beneficial for both the manufacturer and its customers. We propose a Web-based troubleshooting tool that helps customers to self-solve color issues with electrophotographic laser printers when printing solid colors in graphics and text. The tool helps the customer to reconfigure his/her CPW following printing best practices. If the issue is still unresolved, the tool guides the user to search the gamut of the printer for his/her color preference. The usability of the tool was carefully evaluated with human subject experiments. Also, the description and organization of the troubleshooting tasks were continuously reviewed and improved in regular meetings of the development team. In this paper, we describe the troubleshooting strategy, the color preference search algorithm, and the results of the usability experiments.

In personalized digital printing, such as greeting cards, calendars and photo books, people select artworks to match their photos at their preference. Art work design elements are often categorized by occasions, styles, and products. The amount of designs grows significantly, as customers demand more choices and the trends of popular designs rise and fade season by season. It is crucial to manage and understand how design elements are used in order to create most desirable productions. In this paper, we analyze and compare different design tracking systems. Art work designs are labeled, ranked, and cross referenced. For each system, we demonstrate the scale of applications, data collection techniques and its advantages and disadvantages.

HP's digital printing presses consume a tremendous amount of data. The architectures of the Digital Front Ends (DFEs) that feed these large, very fast presses have evolved from basic, single-RIP (Raster Image Processor) systems to multirack, distributed systems that can take a PDF file and deliver data in excess of 3 Gigapixels per second to keep the presses printing at 2000+ pages per minute. This paper highlights some of the more interesting parallelism features of our DFE architectures. The high-performance architecture developed over the last 5+ years can scale up to HP's largest digital press, out to multiple mid-range presses, and down into a very low-cost single box deployment for low-end devices as appropriate. Principles of parallelism pervade every aspect of the architecture, from the lowest-level elements of jobs to parallel imaging pipelines that feed multiple presses. From cores to threads to arrays to network teams to distributed machines, we use a systematic approach to move bottlenecks. The ultimate goals of these efforts are: to take the best advantage of the prevailing hardware options at our disposal; to reduce power consumption and cooling requirements; and to ultimately reduce the cost of the solution to our customers.

Historically, in the 35 years of digital printing research, raster image processing has always lagged behind marking engine technology, i.e., we have never been able to deliver rendered digital pages as fast as digital print engines can consume them. This trend has resulted in products based on throttled digital printers or expensive raster image processors (RIP) with hardware acceleration. The current trend in computer software architecture is to leverage graphic processing units (GPU) for computing tasks whenever appropriate. We discuss the issues for rendering fonts on such an architecture and present an implementation.

In this changing environment in which the artist and designer has access to a wide range of digital imaging tools and technologies, that on first glance, are dedicated to the creation of colour mixtures, why is the digital interface and colour outcome often disappointing? It appears that hardware, software tools and methods for digital printing are not necessarily suited to the specific requirements of the artist. In fact, they are too generalised to obtain a high degree of quality and too inflexible to allow artists to obtain precision and predictability. Is it possible for an artist to mix and print a colour that captures their creative imagination? The motivation for this research is based on how artists mix and print colour by traditional means (painting and printmaking) and how these differ from colour picker tools, slider bars and methods developed for digital printing, and whether it is possible to incorporate both? The paper provides a brief historical background to artists who have developed colour systems to assist their particular colour choices. Based on existing hardware and software, the paper suggests alternative approaches to colour selection, demonstrates methods for the creation of novel inkjet printed palettes, and how these can be visualised and compared.

An important print quality attribute of digital printing equipment deals with the absolute position of the printed image relative to the page. Historically, the most precise method of measuring image to paper (IOP) registration is by scanning a printed sheet on a flatbed scanner. These measurements have been limited to sheets smaller than the full capacity of the printer. In addition, the precision of the measurement has been limited by the accuracy of the scanner itself and the measurement of a few (~4) points on the page have limited the information that can be gathered. The new method proposed in this paper measures IOP registration throughout the sheet in a more precise manner. In a similar fashion, the relative position of the image on both the simplex and duplex side of the print can be determined. In addition, the new method helps link the source of registration errors to individual sub-systems. By generating the individual error sources from a printed sheet enables the understanding of the percentage contribution of each sub-system, prioritizes efforts to obtain better IOP performance, finds initial IOP setup errors of a printing engine, compares different technologies affecting IOP registration in sub-systems and potentially acts as a diagnostic tool for individual sub-systems.

Paper given at Session 7: Spectral Imaging [7241-32]. With the development of digital printing technologies, increasing number of primaries are adopted in colour reproduction systems aiming to improve the quality of the print, in particular, to achieve larger colour gamut, better colour constancy, and smoother colour transition. This introduces a huge challenge to the existing device characterisation techniques, e.g. for the task of calculating the colour gamut of an 11-ink printer alone, things may become mission impossible according to literature.1 This paper aims to address the issue from an artist's point of view, which reveals the fundamentals of the colour gamut of a given medium. The solution is interestingly simple that the empirical method of measuring printed colours for colour gamut calculation remains to be practical and efficient for N-ink printing system characterisation. DOI: 10.1117/12.805925

A test image for color still image processes was developed. The image is based on general requirements on the content and specific requirements arising from the quality attributes of interest. The quality attributes addressed in the study include sharpness, noise, contrast, colorfulness and gloss. These were chosen based on visual relevance in studies of the influence of paper in digital printing. Further requirements such as arising from the use cases of the image are discussed based on eye tracking data and self-report of the usefulness of different objects for quality evaluation. From the standpoint of being sufficiently sensitive to quality variations of the imaging systems to be measured the reference test image needs to represent quality maxima in terms of the relevant quality parameters. As for different viewing times, no object should be exceedingly salient. The paper presents the procedure of developing the test image and discusses its merits and shortcomings from the standpoint of future development.

For quite some time now, the printing business has been under heavy pressure because of overcapacity, dropping prices and the delocalization of the production to low income countries. To survive in this competitive world, printers have to invest in tools that, on one hand, reduce the production costs and, on the other hand, create additional value for their customers (print buyers). The creation of customer portals on top of prepress production systems allowing print buyers to upload their content, approve the uploaded pages based on soft proofs (rendered by the underlying production system) and further follow-up the generation of the printed material, has been illustrative in this respect. These developments resulted in both automation for the printer and added value for the print buyer. Many traditional customer portals assume that the printed products have been identified before they are presented to the print buyer in the portal environment. The products are, in this case, typically entered by the printing organization in a so-called MISi system after the official purchase order has been received from the print buyer. Afterwards, the MIS system then submits the product to the customer portal. Some portals, however, also support the initiation of printed products by the print buyer directly. This workflow creates additional flexibility but also makes things much more complex. We here have to distinguish between special products that are defined ad-hoc by the print buyer and standardized products that are typically selected out of catalogs. Special products are most of the time defined once and the level of detail required in terms of production parameters is quite high. Systems that support such products typically have a built-in estimation module, or, at least, a direct connection to an MIS system that calculates the prices and adds a specific mark-up to calculate a quote. Often, the markup is added by an account manager on a customer by customer basis; in this case, the ordering process is, of course, not fully automated. Standardized products, on the other hand, are easily identified and the cost charged to the print buyer can be retrieved from predefined price lists. Typically, higher volumes will result in more attractive prices. An additional advantage of this type of products is that they are often defined such that they can be produced in bulk using conventional printing techniques. If one wants to automate the ganging, a connection must be established between the on-line ordering and the production planning system. (For digital printing, there typically is no need to gang products since they can be produced more effectively separately.) Many of the on-line print solutions support additional features also available in general purpose e-commerce sites. We here think of the availability of virtual shopping baskets, the connectivity with payment gateways and the support of special facilities for interfacing with courier services (bar codes, connectivity to courier web sites for tracking shipments etc.). Supporting these features also assumes an intimate link with the print production system. Another development that goes beyond the on-line ordering of printed material and the submission of full pages and/or documents, is the interactive, on-line definition of the content itself. Typical applications in this respect are, e.g., the creation of business cards, leaflets, letter heads etc. On a more professional level, we also see that more and more publishing organizations start using on-line publishing platforms to organize their work. These professional platforms can also be connected directly to printing portals and thus enable extra automation. In this paper, we will discuss for each of the different applications presented above (traditional Print Portals, Web2Print applications and professional, on-line publishing platforms) how they interact with prepress and print production systems and how they contribute to the improvement of the overall operations of a printing organization.

Due to the rise in performance of digital printing, image-based applications are gaining popularity. This creates needs for specifying the quality potential of printers and materials in more detail than before. Both production and end-use standpoints are relevant. This paper gives an overview of an on-going study which has the goal of determining a framework model for the visual quality potential of paper in color image printing. The approach is top-down and it is founded on the concept of a layered network model. The model and its subjective, objective and instrumental measurement layers are discussed. Some preliminary findings are presented. These are based on data from samples obtained by printing natural image contents and simple test fields on a wide range of paper grades by ink-jet in a color managed process. Color profiles were paper specific. Visual mean opinion score data by human observers could be accounted for by two or three dimensions. In the first place these are related to brightness and color brightness. Image content has a marked effect on the dimensions. This underlines the challenges in designing the test images.

Digital printing technology represents a counterfeiting threat and a counterfeiting deterrence opportunity. Digital reproduction methods have been used to produce holographic and printed features similar to those on banknotes. As digital technology continues to improve, the quality of those features will become nearly indistinguishable from intaglio printing, offset printing and holograms. Optically active devices and inks have been useful to slow counterfeiters, but security document and feature designers need more tools. The toolbox for digital technologies is very large and being exploited by the counterfeiters, but their toolbox has been limited to commercially available digital technologies. Security designers also need to take advantage of this toolbox with the additional lever of secure materials. By leveraging digital technologies with secure materials, variable information and integration with other security features, security document designers can create new, attractive features that are hard to replicate. The high level of difficulty to create security materials in the sub-micron to nanometer size range with multiple functionalities is one barrier. Creating inks that are formulated to fit the stringent requirements for custom digital printing methods creates another barrier to unauthorized reproduction. All of the other valuable aspects of digital technology are therefore accessible only to those with access to these secure materials. Leveraging these digital materials to make optical effects make them useful for the end-user authentication. Furthermore, use of digital technologies allows the incorporation of variable data that can be authenticated visually or using proprietary algorithms and detection / sorting equipment.

Publishing industry is experiencing a major paradigm shift with the advent of digital publishing technologies. A large number of components in the publishing and print production workflow are transformed in this shift. However, the process as a whole requires a great deal of human intervention for decision making and for resolving exceptions during job execution. Furthermore, a majority of the best-of-breed applications for publishing and print production are intrinsically designed and developed to be driven by humans. Thus, the human-intensive nature of the current prepress process accounts for a very significant amount of the overhead costs in fulfillment of jobs on press. It is a challenge to automate the functionality of applications built with the model of human driven exectution. Another challenge is to orchestrate various components in the publishing and print production pipeline such that they work in a seamless manner to enable the system to perform automatic detection of potential failures and take corrective actions in a proactive manner. Thus, there is a great need for a coherent and unifying workflow architecture that streamlines the process and automates it as a whole in order to create an end-to-end digital automated print production workflow that does not involve any human intervention. This paper describes an architecture and building blocks that lay the foundation for a plurality of automated print production workflows.

This paper addresses the variations and adaptations of processes needed for verifying print quality in real time for high-speed digital printers. The term high-speed is here defined to be more than 750 printed pages per minute. The processes used for print verification are based on very high speed image processing technology applied to scanned images of the printed pages. Print verification is done by scanning the printed copies on the obverse and reverse web sides thereby forming two streams of digitized images. Digitized images from each scanned image stream are then spatially aligned page by page, line by line and pixel by pixel with digitized images from a corresponding source streams. The accuracy of alignment needed to compensate for the poor dimensional stability of paper creates a need for considerable sophistication in image alignment. The source and aligned scanned images are compared to find pixel sequences that are different. The intent is to identify all differences, either missing-black or unexpected-black, that are larger than a 0.01 inch (0.25 mm) square. These differences may represent unacceptable defects in the printed copies.

In 2001, the sudden downturn of Telecom business changed the optical MEMS landscape. Some MEMS companies who were focusing only on telecom applications shut down (OMM as the most famous example) and many companies stopped their optical MEMS developments (Atmel, Memscap). However, some companies succeed to explore new applications outside the telecom area with their telecom technological platform. Today, there is a renewal of the MOEMS business and there are very interesting market opportunities for DMD. This article describes the new market trends for MOEMS and DMD applications. Several new applications are now appearing aside TV and projections systems that will widespread the use of DMDs. Maskless lithography, wavefront correction (adaptive optics) adaptive front light signal for cars, digital printing are applications currently in development where matrix of micro-mirrors could be used. Maskless lithography is still in a R&D status. It will be a low volume market but high R&D investment application that could benefit to other applications. Market acceptance may be an issue: the two main players ASML and Canon have internal projects under evaluation but it still have to prove that it is an attractive technology. Moreover, other MOEMS markets such are barcode readers, spectrometers, micro bolometers are analyzed and quantified.

Clustered dots screens are widely used in digital printing. Our research focuses on irregular cluster-dot screens. Irregular screens are appealing since there are many more irre gular screens than regular ones. As a result, they provide a larger set of multi-separation screen combinations for avoidi ng interaction between screenin g frequencies of concurrent screens. Their down side is that they often have harmonic artifacts. Our design challenge is to reduce these artifacts’ visual impact. We present frequency-domain based methods to reduce these artifacts’ visual impact. State-of-the-art screens incorporate many, predominantly spatial domain, design considerations which we cannot ignore. Accordingly, the proposed methods are designed to introduce minimal modifications to given screens. The proposed methods eliminate, or reduce the few artifacts visibl e in a set of irregular screens. This wo rk can be generalized to other printing technologies, and to screen design. 1. Introduction Digital Halftoning is the process of rendering digital continuous tone images in two tones (e.g. black and white). The goal is to create a dot pattern such that when viewed through the Human Visual System’s (HVS) low pass, it would look like the original continuous tone image. Various printing technologies limit the halftone dot pattern. For example Electro Photography (EP) rendering requires the dot pattern to be clustered, such as in screens, other considerations motivated screen designers for Liquid Electro Photography (LEP) technology to use also irregular screens. Irregular screens are repetitive only in large groups of cells and consequently may contain low frequency harmonic artifacts, more than regular screens. Harmonic artifacts are addressed in [4,9,10] where they are reduced using random dith er and spatial aver aging. In [11] a spatial cost function is used to minimize artifacts, and the cell centers are stochastically distributed. In [2] screen parameters (lpi and angle) are analyzed fo r artifacts. It provides for parameter sel ection identifying screen sets with least disturbing potential artifacts. Cluster shape is addressed in [5] by slightly and randomly distorting the halftone in each halftone cluster. Other methods venture out of the standard screening conventions, for example [7] removes tones with artifacts from the screen, and [3] uses green noise rather than grid based screens. A method for designing re gular monochrome screens is described in [8]. It is based on an optimization method known as Direct Binary Search (DBS). Resulting slight modifications in cluster seed locations create blue-noise type highlight and shadow patterns and regular cluster dot mi d-tone patterns, all in the same screen. Screens can be used for color images by applying a different screen to each color separation independently. Thus, single separation screens have to fit to each other. Specifically, good single separation screens can be used together in print only if overlaying two or more screens does not produce a low frequency artifact [1]. The scarcity of regular screens that can be combined to compatible multi-separation screen sets motivates using irregular screens, which require special design due to prevalence of harmonic artifacts. Our work is motivated by the fact that both single-separation harmonic-artifacts and multi-separation beating are a result of the dot pattern. As such they may be reduced by slight modifications of the dot pattern. Given a screen, we optimize cluster shapes to reduce the over all artifact level. The goal was to intro duce minimal changes so as to preserve as much of the spatial characteristics of the input screen; however the same methodology could be used for screen design. In the next section we detail our screening artifact model, in Section 3 we present artifact reduction methods, and in Section 4 we briefly discuss the results. 2. The model We look for the causes of visible harmonic artifacts in the screen’s dot patterns. Harmonic artifacts have harmonic causes, and thus we analyze the do t patterns in the frequency domain. 2.1. Single-separation artifacts For single separations we model artifacts for every tone leve l separately. The model for artifacts at a given tone level t is based on the 2D DFT of the corresponding dot pattern S

The presentation will demonstrate how through alternative methods of digital print production the Centre for Fine PrintResearch (CFPR) is developing methodologies for digital printing that attempt to move beyond standard reproductiveprint methods. Profiling is used for input and output hardware, along with bespoke profiling for fine art printmakingpapers. Examples of artist’s work, and examples from the Perpetual Portfolio are included - an artist in residencescheme for selected artists wanting to work at the Centre and to make a large-format digital print. Colour is an importantissue: colour fidelity, colour density on paper, colour that can be achieved through multiple-pass printing. Research isalso underway to test colour shortfalls in the current inkjet ink range, and to extend colour through the use of traditionalprinting inks.Keywords: profile, artists’ prints, image quality, digital print, curves, screenprint, colour 1. INTRODUCTION The Centre is developing bespoke approaches to digital printing that concentrate on the production of fine art prints andon the artist making it. Whilst the Centre has a close engagement with photography and photomechanical processes, thisarea of investigation is based on artwork that has not been created outside the computer, and could not have beengenerated or exist other than through digital generation. Working outside the field of new developing digitaltechnologies, the impression is of each sector working in isolation without attention as to the effect of one technology onthe other. Are current technologies associated with digital print: image creation; colour-imaging software; colourmanagement; printers; and colour fidelity technology, developed independently by different manufacturers? Thetransition of data from one device to another is being addressed for a narrow sector of commercial volume printing, butnot for the artist/designer, who has very different requirements from, for example, an industrial firm specialising in four-colour offset litho printing or giclee bureaus making reproductions from existing artworks.Current print technology is neither suited nor philosophically designed for artist led methods of making, resulting in theartist making compromises on quality, which can furthermore be time consuming. Research undertaken so far, andresearch into the future, will consider working methods that consult the artist/designer at every step of the process.The Centre’s research seeks to develop a comprehensive overview of the entire framework of digital imaging, fromimage creation to print: that incorporates how an image is captured or generated; how an artist can further developimages through digital imaging programs other than the mainstream photographic editing software, and eventually, howan image is printed and modifications to printer hardware. One main aspect of this research is to identify andincorporate artist-specific imaging procedures, techniques, qualities and standards into what is principally an industry-dominated field.

The Internet in combination with digital presses has allowed the geographical distribution of manufacturing printed materials. An increasing number of printed pieces is customized for the recipient; when each printed piece is different, conventional proofing fails, because it is impossible to proof the entire print job. One frequent problem in automatically generated pieces is the readability of one page element on top of another element; the color combination can be unreadable or clash. I propose simple algorithms to automatically detect and correct color discriminability problems in variable data printing.

The s-CIELAB color difference metric combines the standard CIELAB metric for perceived color difference with spatial contrast sensitivity filtering. When studying the performance of digital image processing algorithms, maps of spatial color difference between 'before' and 'after' images are a measure of perceived image difference. A general image quality metric can be obtained by modeling the perceived difference from an ideal image. This paper explores the s-CIELAB concept for evaluating the quality of digital prints. Prints present the challenge that the 'ideal print' which should serve as the reference when calculating the delta E* error map is unknown, and thus be estimated from the scanned print. A reasonable estimate of what the ideal print 'should have been' is possible at least for images of known content such as flat fields or continuous wedges, where the error map can be calculated against a global or local mean. While such maps showing the perceived error at each pixel are extremely useful when analyzing print defects, it is desirable to statistically reduce them to a more manageable dataset. Examples of digital print uniformity are given, and the effect of specific print defects on the s-CIELAB delta E* metric are discussed.

There are several important standard laboratory experiments for determining the quality of produced paper in the paper making industry. To know the quality is essential since it defines the use of paper for various purposes. Moreover, customers are expecting a certain degree of quality. Many of paper printability tests are based on off-line visual inspection. Currently these tests are done by printing test marks on a piece of paper and then observing the quality by a human evaluator. In this report visual inspection on paper by machine vision is discussed from a point of off-line industrial measurements. The work focuses on the following paper printability problems: missing dots (Heliotest), print dot density, unevenness of printing image, surface strength (IGT), ink setting, linting, fiber counting, and digital printing. Compared to visual inspection by human evaluation, automated machine vision systems could offer several useful advantages: less deviations in measurements, better measurement accuracy, new printability parameters, shorter measurement times, less manpower to monotonic measurements, many quality parameters by one system, and automatic data transfer to mill level information systems. Current results with paper and board samples indicate that human evaluators could be replaced. However, further research is needed since the printability problems vary mill by mill, there is a large number of various paper and board samples, and the relationships between off-line and on-line measurements must be considered.

The objective of this investigation is to establish whether it is possible to produce a practical forensic tool that can identify the production sources of printed text from different digital print engines. The identification of print using an automated machine system is important because although expert observers can be employed for this task, there are cases when they make mistakes or do not possess the required knowledge. Therefore the development of an automated print identification system is under consideration. It is envisaged that the system will be useful in solving criminal cases involving the analysis of fraudulent replication of official documents, threatening letters and the counterfeiting of consumer products. The methodology used in this investigation employed a digital image analysis system and specially developed software to measure the shape characteristics of text characters. The information about the shapes of the text characters can be stored in a database along with the corresponding data about the print engines that produced them. A database search engine can then be used to classify text characters of unknown origin. The paper will report on the methodology and techniques used in the investigation and the latest experimental results for the project.

The colors in printed products should be known before printing. There are now many inexpensive inkjet printers able to print color. Using color management systems they can be used as proofing devices. The color gamut and the stability of these devices were assessed. There are tow main results of this project: We have developed a procedure and the tools to qualify proofing devices and we have shown that there are inexpensive devices suited for proofing newspaper print. The gamut is wide enough to simulate offset printing on uncoated paper and it is possible to simulate the color tint of the paper on which the final product will be printed. It is possible to attain a small mean Delta E between such an inexpensive proof and the final printed product. This Delta E is often smaller than between an analog proof and the final printed product. The prerequisites are calibration of the printer and color profiles of both the printer and the printing process to be simulated.

Electronic printing is now 25 years old. A great deal of progress has been made as evidenced by the great number of electronic printers and their associated technologies. This paper illustrates three simple metrics with which to analyze electronic printer technology. The metrics are not necessarily intended to be anything profound or deterministic but appear to illustrate some relative constants as well as significant improvements in printers that indicate a trend whose final outcome is yet to be seen. Since electronic printers are basically information delivery devices, they can be analyzed as to their information delivery capability on a cost-performance basis. The three metrics utilized in this paper involve a number of characteristics such as printer weight, speed, spatial printing density and color. Over 170 printers area used in this analysis dating from the birth of the laser printer in the mid-1970s up to the present time. This metric oriented view of the technology may give us some insight as to where the electronic printing industry is going on a cost/performance basis as well as where new products should be aimed so that they provide the desired market impact.

The aim of this paper is to present a mathematical discussion of some aspects of digital printing, and other related problems such as analog/digital data conversion. In particular, we present results on the boundedness of the errors generated by error diffusion (and related) algorithms, and discuss the relationship between some of the mathematical questions arising in digital printing and some classical mathematical problems such as symbolic dynamics, the chairman assignment problem, and coding theory.

Accurate, automatic color reproduction is the goal of much of color technology. However there is a need to improvereproduction in only the luminous or gray axis. Quadtone reproduction takes advantage of the four device CMYK color planesto provide greater gray-scale depth within the limitations of 8-bit per channel band-width. "Quadtone" refers to photosreproduced using four tones of the same colorant. It is the printed imposition of four carefully selected shades of ink thatresult in a greater number of densities. Guerrilla printing is a collection of algorithms using the CMYK channels to simulatetraditional photography on an inkjet printer. Guerrilla printing increases density values, defines detail and produces nearcontinuous-tone screens.Key Words: density, frequency modulation screening, inkjet printers, luminosity, quadtone

Moire formation is often a major problem in the printing applications. These artifacts introduce new low frequency components which are very disturbing. Some printing techniques, e.g. gravure printing, are very sensitive to moire. The halftoning scheme used for gravure printing can basically be seen as a 2D non-isotropic subsampling process. The more problem is much more important in gravure printing than in conventional digital halftoning since the degree of freedom in constructing halftone dots is much more limited due to the physical constraints of the engraving mechanism.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

An effective and flexible data conversion controller for ink jet printing is proposed in this paper. It provides the capability of processing firing data to meet the requirements of both firing sequence and firing timing of the cartridge. This print data is arranged according to the nozzle layout of a selected print cartridge and the printing direction. Then output the arranged data to the firing driver of print cartridge. A hardware architecture is proposed to serve the needs of data conversion. It is an effective design that consists of two appointed selections of nozzle firing sequence and fixed nozzle pad mapping. Moreover, the proposed architecture provides programmable firing timing and it can be switched between black or color printing mode. The core technology of this data conversion hardware is now applied to an ASIC of ink jet fax engine by OES/ITRI.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

In recent years, ink jet has emerged as one of the mainstream printing technologies. Since its market inception in 1985, Hewlett-Packard's thermal ink jet technology (TIJ) has evolved progressively from a 12 nozzle 96 dpi print head to a 300 nozzle 600 dpi print head. TIJ has made rapid progress enabling it to print text output on plain paper that challenges laser printers, and realistic photographic images that rival silver halide, at a low consumer price. Thermal ink jet technology continues to enjoy a greater unit market share than any other digital printing technology and all other ink jet technologies combined. The driving forces for the advancement of TIJ have been better, faster, and cheaper printers for consumers. These goals involve key attributes such as ink performance (gamut, sharpness, fastness), minimum deliverable colorant (drop volume), rate of colorant delivery (firing frequency, nozzle integration, firing chamber volume), and print engine cost per unit throughput. In this paper, key technology challenges for TIJ will be outlined. New materials and new processes that are required for the advancement of thermal ink jet printing are discussed. Recently, competing ink jet methods have (re-)emerged, notably piezoelectric ink jet. References will be made to piezoelectric ink jet when appropriate.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The term thermal printing includes a very broad technological basis of printing an image with the use of thermal energy. The printing process involves one of the following mechanisms: (1) transfer of dyes, (2) transfer of pigments or dyes with a carrier, or (3) formation of dyes on a substrate. Starting in the late fifties thermal printing has been used in the textile business. This technology was widely used later in printing tickets, receipts and bar codes and in fax machines. The application of this printing technology in color hard copies was pioneered by Dai Nippon and first commercialized by Sony in the Mavica electronic photographic system in the late eighties. Since then many companies have participated, in various capacities, in the thermal printing business. At this time there is no doubt that thermal dye transfer printing with the use of resistive or laser printhead gives the highest photographic image quality in digital printing as compared to an optical printing system with silver halide materials.

The digital camera market is growing at an explosive rate. At the same time, the quality of photographs printed on ink- jet printers continues to improve. Most of the consumer cameras are designed with the monitor as the target output device and ont the printer. When a user is printing his images from a camera, he/she needs to optimize the camera and printer combination in order to maximize image quality. We describe the details of one such method for improving image quality using a AGFA digital camera and an ink jet printer combination. Using Adobe PhotoShop, we generated optimum red, green and blue transfer curves that match the scene content to the printers output capabilities. Application of these curves to the original digital image resulted in a print with more shadow detail, no loss of highlight detail, a smoother tone scale, and more saturated colors. The image also exhibited an improved tonal scale and visually more pleasing images than those captured and printed without any 'correction'. While we report the results for one camera-printer combination we tested this technique on numbers digital cameras and printer combinations and in each case produced a better looking image. We also discuss the problems we encountered in implementing this technique.

Digitalization within the graphic arts industry is described and it is explained how it is improving and changing the print production strategies and which new kinds of print production systems are developed or can be expected. The relationship of printed media and electronic media is analyzed and a positioning for the next century is given. The state of the art of conventional printing technologies, especially using direct imagine techniques, and their position within the digital workflow are shortly described. Non-impact printing multicolor printing systems are explained, based on general design criteria and linked to existing and newly announced equipment. The use of high-tech components for building up successful systems with high reliability, high quality and low production costs is included with some examples. Digital printing systems open many opportunities in print production: distributed printing, personalization, print and book on demand are explained as examples. The overview of the several printing technologies and their positioning regarding quality and productivity leads to the scenario about the important position of printed media, also in the distant future.

Last generation of digital printer is usually characterized by a spatial resolution enough high to allow the designer to realize a binary CGH directly on a transparent film avoiding photographic reduction techniques. These devices are able to produce slides or offset prints. Furthermore, services supplied by commercial printing company provide an inexpensive method to rapidly verify the validity of the design by means of a test-and-trial process. Notably, this low-cost approach appears to be suitable for a didactical environment. On the basis of these considerations, a set of software tools able to design CGH's has been developed. The guidelines inspiring the work have been the following ones: (1) ray-tracing approach, considering the object to be reproduced as source of spherical waves; (2) Optimization and speed-up of the algorithms used, in order to produce a portable code, runnable on several hardware platforms. In this paper calculation methods to obtain some fundamental geometric functions (points, lines, curves) are described. Furthermore, by the juxtaposition of these primitives functions it is possible to produce the holograms of more complex objects. Many examples of generated CGHs are presented.

Through a joint agreement with the Indiana-Marion County Forensic Laboratory Services Agency, the Institute for Forensic Imaging conducted a pilot program to investigate crime lab applications of a digital darkroom. IFI installed and staffed a state-of-the-art digital darkroom in the photography laboratory of the Indianapolis-Marion County crime lab located at Indianapolis, Indiana. The darkroom consisted of several high resolution color digital cameras, image processing computer, dye sublimation continuous tone digital printers, and CD-ROM writer. This paper describes the use of the digital darkroom in several crime lab investigations conducted during the program.