Using color management to automate the color reproduction of 3-D images procured via a digital camera/3-D scanner

The use of digital photography is migrating from the major applications in pho tojournalism to professional studio photography. Traditional service bureaus such as professional photo labs and prepress trade shops are adding digital imaging services to their film-based services. Also, businesses such as advertising agencies and publishers, who traditionally outsource work to service bureaus, are bringing digital imaging services in-house. State of the art imaging technology empowers users with new tools, but does not guarantee that the task of generating accept able image reproductions will be easier. The basic problem in the desktop color prepress environment is that each com ponent in this open system handles color differently. Miscommunication between devices results in user frustration with an unpredictable, inconsistent, and inaccurate color system. The solution to this problem is to assess one\u27s workflow and adopt a color management system (CMS). The purpose of CMSs is to help users maintain color integrity throughout their desktop system and to automate the color separation process. This thesis project investigated the possibility of applying a comprehensive CMS to automate the color reproduction of 3-D images procured with a digital camera. Automatic exposure by Leaf System\u27s Lumina digital camera and automatic adjustments for tone reproduction, gray balance, and color correction by Kodak\u27s PCS100 CMS were employed. The experimental design began with the calibration of each component in the imaging chain. Next, a three-dimensional test scene of objects displaying tone and color variety was digitized by the Lumina camera under specific studio lighting conditions. And, under the exact studio conditions, a Kodak Q-60 test target was digitized; this image file was used to characterize a device profile for the Lumina digital camera. The digitized 3-D test scene file was sent through a color-managed workflow for automatic color reproduction. IX The automated, color-managed reproduction process was as follows: 1) select monitor, input, effect, and output profiles in the PCS100 Color Manager 2) acquire image via Photoshop on a Macintosh 3) image color conversion with Kodak\u27s PCS100 plug-ins by applying custom input profile, output simulation profile, and 3M Matchprint output profile 4) film output via Agfa Selectset 5000, and 5) 3M Matchprint color proofing to SWOP (Specifications for Web Offset Printing). Subjective evaluation was based on the single stimulus method. Visual assess ments were performed by twenty color-tested judges with experience in printing or photography. A set of ten color proofs of identical image were individually evaluated for acceptability. The criteria for acceptable color reproduction includ ed tone reproduction, gray balance, and color correction. Proofs that received high average scores (\u3e80%) were determined acceptable. Analysis of the results determined that with proper calibration and CMS color conversion technology, one can deliver acceptable tone reproduction and pleasing color. Gray balance was determined unacceptable for all proofs based solely on a perceived yellowish-green cast in the MacBeth ColorChecker\u27s three-quarter tone patch. Excluding the gray balance factor, four proofs were determined acceptable for tone and color reproduction. Objective evaluation was made to further assess the color accuracy from original to acceptable proof, and to correlate colorimetric differences with the visual assessments. Quantitative assessment was based on colorimetric CIEL*a*b* mea surements and calculated color differences (AE, AL*, AC*, AHab*) of MacBeth color patches and 3-D objects. Objects in the original scene and corresponding image areas in the proofs were measured in order to study variations in hue, light ness, and saturation. Analysis of the results demonstrated that overall, the images in the proof were lighter, less saturated, and had small hue shifts compared to the original. The proofed image would probably be a poor match to the original in terms of objective color accuracy. But for this thesis project, color proof accept ability was determined by the subjective, visual evaluations

Investigation into the capturing, manipulating, calibrating and outputting of black and white images on a Xerox Docutech

It is the purpose of this investigation to determine whether or not the output quality of black and white images on a Xerox Docutech can be enhanced. The Docutech is a black and white digital printing device. In times of a growing demand for on-demand printing and publishing, the Docutech not only has to reproduce text and graphics properly but also has to cope with the increasing task of rendering images. Although there are multiple options to improve the output quality, this project focuses on the impact of image capturing on the output. As a result of this investigation, a user\u27s manual should help to achieve satisfying reproductions on the Docutech. The project goals are reached by extensive testing and a careful evaluation of the experiments by visual, densitometric and statistical means. Prior to any testing and as a prerequisite for the project, the print characteristic of the Docutech is determined. With stable printing conditions as a starting point, the impact of the scanning process is investigated. For this purpose, four different scanners ranging from flatbed, desktop devices to high-end scanning systems are used to capture two test images. Those images are manipulated within this process step to improve the rendering quality of the printed output. The printed output is analyzed finally by statistical means to base the perceived quality differences on the objective judgement of a larger audience of observers. Focusing on the results of this evaluation process, one will find that the output quality can be enhanced. Not only are adjustments found which increase the perceived qualify of the printed result but also is insight gained into the printing process and its limitations. There is no doubt that the Docutech has its restrictions but its low cost and low quality image is not justified. It is possible to improve the output quality of black and white reproductions by applying the basic rules of image reproduction. Thus, utilizing the capabilities of this digital printing device efficiently, one can achieve satisfying output quality

Using measured photography to obtain optimal results from CCD Color Scanners

With the advent of desktop color scanners in the electronic prepress production environment, quality in color separations from transmissive originals has become erratic. The cause of this fluctuation is, in part, due to the transition from PMT to CCD-based scanning technology. Whereas, PMT scanners tend to have a broad dynamic range, that of CCD scanners is more limited. This characteristic adversely affects the quality of color separations by causing additional tone compression. An original transparency typically has a shadow density of 3.00 and a diffused highlight density of 0.30 for an overall density range of 2.70. On a four-color heatset web press with coated stock, the maximum reproducible tonal range corresponds to a density of 1.80. The difference in density of 0.90 between the original and the press sheet is unable to fit through the printing window unless it undergoes considerable tone compression. This project was based on two hypotheses. The first was that the lower the tonal range of a transmissive original the more readily lower-midtone-to-shadow tonality could be retained in the separations produced by a CCD scanner and related equipment. The second was that exposure latitude in the separations would decrease with increasing tonal range. The first stage of production was to produce twelve test transparencies by photograph ing a still life set to four tonal ranges: 3.5, 4.5, 5.5, and 6.5 f/stops. Within each range, three images were selected to represent normal exposure, 1/2 f/stop overexposure, and 1/2 f/stop underexposure. Comparison of halftone proofs, made from separations of the normallyexposed transparencies, were later used for the first hypothesis. Proofs from the 1/2 f/stop over- and 1/2 f/stop underexposures were compared with the normal exposures to test the second hypothesis. vm The twelve test transparencies were first scanned on the Dainippon Screen SG-608 to produce a set of best-of-kind reference separations and halftone proofs. Next, the trans parencies were scanned on two midrange 12-bit CCD scanners, one a Pixelcraft CIS 4520RS, the other an Agfa Horizon. Separations for both were produced with Color Access 1.3.3 software on a Macintosh Quadra 700 computer, linked to an Agfa SelectSet 5000 image-setter via an Agfa 5000PS Star Plus RIP. The image files were placed in an 8 1/2 X 11 QuarkXPress page with a 20% gray surround prior to output. Halftone proofs were produced with the Fuji Color Art proofing system, then viewed under 5000 Kelvin lighting. Three methods were used for comparison: visual evaluation by the author, densitometric measurement, and evaluation by 32 independent judges. Only proofs from the two CCD scanners were shown to the judges. Proofs from the SG-608, of noticeably higher quality, were used for reference. The four proofs from separations produced by normally-exposed originals were used to examine the first hypothesis. Two groups of proofs, one for each scanner, were ranked by the judges according to best-to-worst rendition of lower-midtone-to-shadow detail. The rank ings for both groups placed the 3.5 f/stop tonal ranges first, 4.5 f/stop second, 5.5 f/stop third, and 6.5 f/stop fourth. Visual evaluation by the author ranked the proofs in the same order, establishing a 100% correlation. Increases in density range were also expected to follow the 3.5 to 6.5 f/stop ranking. But actual measurements showed increases in density to 4.5 f/stops, then a pronounced drop of 0.25 or greater for the 5.5 and 6.5 f/stop ranges. This demonstated that the higher tonal ranges exceeded the capacity of the CCDs to make a full response, indicating that limited dynamic range was causing abrupt increases in tone compression. To determine the validity of the second hypothesis, the judges examined two groups of twelve proofs each, corresponding to the separations for normal, 1/2 f/stop over- and 1/2 f/stop underexposed originals within each of the four tonal ranges. For the Agfa Horizon, the rankings were 3.5 f/stop tonal range first, 4.5 f/stop second, 5.5 f/stop third, and 6.5 f/stop fourth. With the Pixelcraft CIS 4520RS, the rankings were 3.5 f/stop first, 6.5 f/stop second, 5.5 f/stop third, and 6.5 f/stop fourth. The misranking of the 6.5 f/stop range in second place indicated the difficulty the judges experienced in distinguishing between higher tonal ranges due to the increasing effects of tone compression. Again, densitometric measurements did not support the rank ings of the judges or the author because the densitometer could not distinguish between small tonal range differences due to good exposure latitude and those differences due to blocked shadow tonality resulting from tone compression. A procedure was devised for mathematical assessment of tonal range differences. Using the change in density between adjacent tonal ranges, a value was derived which could be expressed as a fraction of the inital 1 f/stop difference between ranges ( 1 f/stop = 0.30 den sity units). For example, the 3.5 f/stop normal exposure for the Agfa Horizon had a tonal range of 1.73 and the 4.5 f/stop normal exposure had a tonal range of 2.02. The change from 3.5 to 4.5 f/stops is +0.29. Expressed as a percentage, 0.29 -0.30 = 97%. This value showed that the scanner made a nearly complete response in translating tonal range differences in the original transparency to tonal range differences in the separations. Further refinement of these calculations is needed to reflect differences in gamma and tone compression between the original transparencies and the halftone proofs. The findings of this study demonstrate that optimal results from a CCD or PMT scan ner can only be obtained if the tonal range of the original scene is less than 4.5 f/stops. When the 4.5 f/stop range was exceeded, the CCD scanners responded with an immediate deterioration of lower-midtone-to-shadow tonality. In comparison, PMT scanner displayed a more gradual degradation of lower-midtone-to-shadow tonality, in keeping with its greater dynamic range

The Wiltshire Wills Feasibility Study

The Wiltshire and Swindon Record Office has nearly ninety thousand wills in its care. These records are neither adequately catalogued nor secured against loss by facsimile microfilm copies. With support from the Heritage Lottery Fund the Record Office has begun to produce suitable finding aids for the material. Beginning with this feasibility study the Record Office is developing a strategy to ensure the that facsimiles to protect the collection against risk of loss or damage and to improve public access are created.<p></p> This feasibility study explores the different methodologies that can be used to assist the preservation and conservation of the collection and improve public access to it. The study aims to produce a strategy that will enable the Record Office to create digital facsimiles of the Wills in its care for access purposes and to also create preservation quality microfilms. The strategy aims to seek the most cost effective and time efficient approach to the problem and identifies ways to optimise the processes by drawing on the experience of other similar projects. This report provides a set of guidelines and recommendations to ensure the best use of the resources available for to provide the most robust preservation strategy and to ensure that future access to the Wills as an information resource can be flexible, both local and remote, and sustainable

Advertising towards new millenium : using digital photographic techniques & equipment

ThesisThe approach to the discussions of this script will be to start with a delineation of this field of study, reasons for the decision, equipment required, followed by a discussion of the field of specialization as well as a discussion of the advantages and disadvantages of the chosen field of specialization

Digital imaging technology assessment: Digital document storage project

An ongoing technical assessment and requirements definition project is examining the potential role of digital imaging technology at NASA's STI facility. The focus is on the basic components of imaging technology in today's marketplace as well as the components anticipated in the near future. Presented is a requirement specification for a prototype project, an initial examination of current image processing at the STI facility, and an initial summary of image processing projects at other sites. Operational imaging systems incorporate scanners, optical storage, high resolution monitors, processing nodes, magnetic storage, jukeboxes, specialized boards, optical character recognition gear, pixel addressable printers, communications, and complex software processes

An Investigation into the relationship between contrast and resolution of a printing system using the RIT contrast resolution test target

A problem arises when different printing systems are used to print images. Different systems have considerably different contrast and resolution capabilities while an individual printing system might have a low resolution capability, the system may have the ability to render low contrast detail. Similarly, if a printing system has a high resolution capability, it does not necessarily mean that such a system has the ability to render low contrast detail well. Such contrast and resolution restrictions may be attributed to the capabilities of the PostScript interpreter, the screening method used by the RIP, the image transfer method of the output device, the substrate used, or a combination of these factors. The RIT Contrast Resolution Test Target has been developed to measure the relationship between contrast and resolution of a printing system. The target measures the contrast-resolution capability of the printing system in both the horizontal and vertical print direction of the printing device. A graph can be plotted to show the Contrast Sensitivity (CS) for the printing system. From this distribution, a contrastresolution- volume (CRV) can be calculated to produce a quantitative contrast-resolution measurement for an individual printing system. The hypothesis of this thesis is that the RIT Contrast Resolution Test Target can provide a method of discriminating the CRV of marking engines and screening methods by using analysis methods intended for use with the target. The target was printed on several printing systems. 12 observers were used to measure the target. The observers were given instruction on proper target reading, and their observations were recorded as CRV measurements. The CRV values for all colors from each system were averaged for each observer. The averaged data was entered into a two-way ANOVA test, where the two dimensions in the test were systems and observers. The results of the ANOVA test showed that there was significant variance in the average CRV values from each system, and the hypothesis of this thesis was accepted. In addition, the ANOVA test indicated that there was significant variance between the observers readings. Although each observer used a different judging criteria, it was concluded that the observers evaluated the different systems relative to one and other in almost the same sequence

Digital Color Imaging

This paper surveys current technology and research in the area of digital color imaging. In order to establish the background and lay down terminology, fundamental concepts of color perception and measurement are first presented us-ing vector-space notation and terminology. Present-day color recording and reproduction systems are reviewed along with the common mathematical models used for representing these devices. Algorithms for processing color images for display and communication are surveyed, and a forecast of research trends is attempted. An extensive bibliography is provided

Visual Prototyping of Cloth

Realistic visualization of cloth has many applications in computer graphics. An ongoing research problem is how to best represent and capture appearance models of cloth, especially when considering computer aided design of cloth. Previous methods can be used to produce highly realistic images, however, possibilities for cloth-editing are either restricted or require the measurement of large material databases to capture all variations of cloth samples. We propose a pipeline for designing the appearance of cloth directly based on those elements that can be changed within the production process. These are optical properties of fibers, geometrical properties of yarns and compositional elements such as weave patterns. We introduce a geometric yarn model, integrating state-of-the-art textile research. We further present an approach to reverse engineer cloth and estimate parameters for a procedural cloth model from single images. This includes the automatic estimation of yarn paths, yarn widths, their variation and a weave pattern. We demonstrate that we are able to match the appearance of original cloth samples in an input photograph for several examples. Parameters of our model are fully editable, enabling intuitive appearance design. Unfortunately, such explicit fiber-based models can only be used to render small cloth samples, due to large storage requirements. Recently, bidirectional texture functions (BTFs) have become popular for efficient photo-realistic rendering of materials. We present a rendering approach combining the strength of a procedural model of micro-geometry with the efficiency of BTFs. We propose a method for the computation of synthetic BTFs using Monte Carlo path tracing of micro-geometry. We observe that BTFs usually consist of many similar apparent bidirectional reflectance distribution functions (ABRDFs). By exploiting structural self-similarity, we can reduce rendering times by one order of magnitude. This is done in a process we call non-local image reconstruction, which has been inspired by non-local means filtering. Our results indicate that synthesizing BTFs is highly practical and may currently only take a few minutes for small BTFs. We finally propose a novel and general approach to physically accurate rendering of large cloth samples. By using a statistical volumetric model, approximating the distribution of yarn fibers, a prohibitively costly, explicit geometric representation is avoided. As a result, accurate rendering of even large pieces of fabrics becomes practical without sacrificing much generality compared to fiber-based techniques