Test Targets 7.0: A Collaborative effort exploring the use of scientific methods for color imaging and process control

Test Targets is a culmination of teaching and learning that reflects quality and analytic aspects of printing systems and their optimization. The creation of the Test Targets publication is a total experience that reflects the innovation, problem solving, and teamwork of the diverse team of faculty, staff, students, and professionals responsible for its contents and production

Test Targets 10: A Collaborative effort exploring the use of scientific methods for color imaging and process control

Th ere are six papers that were written, peer reviewed, and published in Test Targets 10. Two papers focus on printing standardization and conformity assessment. Chung describes aims and tolerances specified in ISO 12647-2 and the use of color measurement and data analysis for conformity assessment. Urbain and Khoury describe data reception requirements in ISO 12647-2 and ISO 15930 and the use of a test pdf file to assess conformity of any pdf workflow. Test Targets 10 will likely be remembered as the publication that covers OBA (optical brightening agents). Two papers focus on OBA. Tian and Chung report the effect of paper containing OBA on printed colors and how such effect can be corrected using different mathematics. Sigg and Millward report the stability of OBA as a function of exposure to light over time. In addition, Gallery of Visual Interest shows side-by-side the visual effect of pictorial and synthetic color images printed on paper with and without OBA. Printing conformity is result-oriented and does not dictate the press calibration method used. The fifth paper, authored by Wang, compares the compatibility of two press calibration methods, TVI and G7, by means of gradation compensation and press run simulation. Printing conformity requires that correct inks and paper be used. Verifying that correct inks are used is outside the capability of a printer. Th e sixth paper, authored by Zhang, explores an alternative ink drawdown and ink verification method that could be implemented by printers. Test Forms is a regular feature of Test Targets. We are pleased to showcase pictorial color reference images, Roman 16 Reference Images, courtesy of Bundesverband Druck und Medien e.V. (bvdm), and many possible uses of these images for printing process control and for color management studies. For example, we can compare the appearance of an image printed from the supplied CMYK file with the image from a supplied RGB file that was converted to CMYK by a color management application

Defining Acceptable Colour Tolerances for Identity Branding in Natural Viewing Conditions

Graphic arts provide the channel for the reproduction of most brand communications. The reproduction tolerances in the graphic arts industry are based on standards that aim to produce visually acceptable outcomes. To communicate with their target audience brands, use a set of visual cues that may include the definition of a single or combinations of them to represent themselves. The outcomes are often defined entirely by their colour specification without an associating it to target parameters or suitable colour thresholds. This paper researches into the feasibility of defining colour tolerances for brand graphical representations. The National Health Service branding was used as a test case borne out of a need to resolve differences between contracted suppliers of brand graphics. Psychophysical evaluation of colour coded navigation used to facilitate wayfinding in hospitals under the varying illuminances across the estate was found to have a maximum acceptable colour difference threshold of 5ΔE00. The simulation of defined illumination levels in hospitals, between 25-3000 lux, resulted in an acceptable colour tolerance estimation for colour coded navigation of 3.6ΔE00. Using ICC media relative correction an experiment was designed to test the extent to which substrate white points could be corrected for colour differences between brand proofs and reproductions. Branded stationery and publications substrate corrections to achieve visual matches had acceptable colour difference thresholds of 9.5ΔE*ab for solid colours but only 2.5ΔE*ab. Substrate white point corrections on displays were found to be approximately 12ΔE*ab for solids and 5ΔE*ab for tints. Where display media were concerned the use of non-medical grade to view medical images and branded content was determined to be inefficient, unless suitable greyscale functions were employed. A STRESS test was carried out, for TC 1-93 Greyscale Calculation for Self-Luminous Devices, to compare DICOM GSDF with Whittle’s log brightness. Whittle’s function was found to outperform DICOM GSDF. The colour difference formulas used in this research were tested, using near neutral samples 2 judged by observers using estimated magnitude differences. The CIEDE2000 formula was found to outperform CIELAB despite unexpected outcomes when tested using displays. CIELAB was outperformed in ΔL* by CIEDE2000 for displays. Overall it was found that identity branding colour reproduction was mostly suited to graphic arts tolerances however, to address specific communications, approved tolerances reflecting viewing environments would be the most efficient approach. The findings in this research highlights the need for brand visualisation to consider the adoption of a strategy that includes graphic arts approaches. This is the first time that the subject of defining how brands achieve tolerances for their targeted visual communications has been researched

Test Targets 9.0: A Collaborative effort exploring the use of scientific methods for color imaging and process control

Painters spend their lifetime to master visual media by expressing the sense of beauty through conscious arrangement of color and patt erns. Tools and materials they use are prett y standard, but their creativity, as refl ected in their artwork, diff ers from artist to artist and from era to era. RIT School of Print Media publishes Test Targets annually using standard writing and publishing tools to turn ideas into printed pages. Our creativity is refl ected in the exploration of diff erent print media technologies and the visual eff ect they achieve. Th is introduction off ers readers a glance of the topics addressed by RIT students, faculty, and staff in Test Targets 9.0. Th e process ranges from experimentation, documentation, peer review, to fi nished manuscripts. It also describes how we benchmark two diff erent printing technologies, off set and highspeed inkjet, in terms of their tone and color capabilities, and how we use color management to achieve color agreement between these two dissimilar printing technologies

Light Transmission Properties of Lentil (Lens culinaris Medik.) Seed Coat and Effect of Light Exposure on Cotyledon Quality

Cotyledon color is one of the most important quality criteria in the lentil market because the color may correlate well with other quality attributes. Therefore, cotyledon color is an important quality criterion in lentil breeding programs. The objectives of this work were to investigate the variation in optical properties among lentil seed coat types and to determine the effect of light treatment, seed coat presence, and seed coat type on color loss in lentil cotyledon. Light transmission properties of seed coat types were obtained to find out if they differ in their light-blocking ability and protection of the underlying cotyledon from photodegradation. Light reflectivity was measured to investigate if there are recognizable patterns, which might be useful in market class discrimination, quality prediction and disease detection in the seeds. A fiber-optic spectrometer was used to obtain spectral reflectivity and transmission properties of seed coats of 20 lentil genotypes. The reflectivity (0°\32°) and nadir-aligned transmission spectra were measured in the 250 nm to 850 nm wavelength range. An Analysis of Variance (ANOVA) showed that there were significant (p<0.05) differences in light transmission properties of the major seed coat types. A computer vision system was used to study the influence of light exposure on the cotyledon color of red, green, and yellow lentils. Twenty samples from each of the three cotyledon color classes were subjected to six levels of light treatment, namely ultraviolet, full-spectrum visible, red, green, blue, and control (dark) for seven days, at room temperature. This light exposure had a significant effect on all three cotyledon color classes. The effect size was largest in green lentils, smaller in yellow, and least in red lentils. Having established the light-blocking characteristics of the various seed coats and realizing that light exposure does affect the color of lentil cotyledon, the protective effects of different kinds of seed coat against light-induced cotyledon color change was tested. Results showed that some whole green cotyledon lentils experienced color losses in the underlying cotyledon. Red and yellow lentil classes had high levels of colorfastness, and their seed coats successfully protected the cotyledon from these minimal effects. Thus, breeding for seed coat protection may not improve the cotyledon color of Canadian red lentils (the most de-hulled market class), but it may improve the overall quality of green lentils

Assessing the Use of Smartphones in Agriculture

Smartphones are an as yet untapped resource available to agriculture. They are ubiquitous across the globe yet have not previously been tested as a resource available to farmers. Imaging methods such as unmanned aerial vehicles (UAV) and satellite imaging have been well-explored and employed in various aspects of agriculture; however, such methods can be cost-prohibitive and at the mercy of another company or agency. If smartphones could be shown to capture color in such a way that relates in a quantifiable way to data measured by laboratory-grade equipment they could prove to be extremely valuable to farmers. Cutting out expensive and specialized technology for a device already sitting in people’s pockets would benefit farmers around the world. Given this idea, three experiments were designed to assess the color capabilities of smartphone cameras in relation to agricultural applications. The first experiment assessed the capability of smartphone cameras to identify the presence of cyanobacteria in a given water sample based on measurements of color and transmission spectra. These data were then related to color captured by four smartphones. Additionally, the measurements were used to create a preliminary customized Color Checker(TM)-inspired chart for use in identification of cyanobacteria. Current techniques employed by the state of New York for identifying cyanobacteria in water are cumbersome, involving week-long testing in government labs. This project is an attempt to simplify the process by using image capture with smartphones. The second assessment was similar to the first, with tomatoes in place of cyanobacteria. Five smartphone devices were used to image tomatoes at different stages of ripeness. A relationship was found to exist between the hue angles taken from the smartphone images and as measured by a spectroradiometer. A tomato Color Checker(TM) was created using the spectroradiometer measurements. The chart is intended for use in camera calibration for future imaging of tomatoes. The final assessment was an online experiment, wherein participants were asked to choose a color from an array generated from images of tomatoes that best represent the color of the tomato. This was a first step toward understanding which characteristics people use to categorize a crop as ripe and how those characteristics are rendered by smartphone imaging

Determining Material Structures and Surface Chemistry by Genetic Algorithms and Quantum Chemical Simulations

With the advent of modern computing, the use of simulation in chemistry has become just as important as experiment. Simulations were originally only applicable to small molecules, but modern techniques, such as density functional theory (DFT) allow extension to materials science. While there are many valuable techniques for synthesis and characterization in chemistry laboratories, there are far more materials possible than can be synthesized, each with an entire host of surfaces. This wealth of chemical space to explore begs the use of computational chemistry to mimic synthesis and experimental characterization. In this work, genetic algorithms (GA), for the former, and DFT calculations, for the latter, are developed and used for the in silico exploration of materials chemistry. Genetic algorithms were first theorized in 1975 by John Holland and over the years subsequently expanded and developed for a variety of purposes. The first application to chemistry came in the early 1990’s and surface chemistry, specifically, appeared soon after. To complement the ability of a GA to explore chemical space is a second algorithmic technique: machine learning (ML) wherein a program is able to categorize or predict properties of an input after reviewing many, many examples of similar inputs. ML has more nebulous origins than GA, but applications to chemistry also appeared in the 1990’s. A history perspective and assessment of these techniques towards surface chemistry follows in this work. A GA designed to find the crystal structure of layered chemical materials given the material’s X-ray diffraction pattern is then developed. The approach reduces crystals into layers of atoms that are transformed and stacked until they repeat. In this manner, an entire crystal need only be represented by its base layer (or two, in some cases) and a set of instructions on how the layers are to be arranged and stacked. Molecules that may be present may not quite behave in this fashion, and so a second set of descriptors exist to determine the molecule’s position and orientation. Finally, the lattice of the unit cell is specified, and the structure is built to match. The GA determines the structure’s X-ray diffraction pattern, compares it against a provided experimental pattern, and assigns it a fitness value, where a higher value indicates a better match and a more fit individual. The most fit individuals mate, exchanging genetic material (which may mutate) to produce offspring which are further subjected to the same procedure. This GA can find the structure of bulk, layered, organic, and inorganic materials. Once a material’s bulk structure has been determined, surfaces of the material can be derived and analyzed by DFT. In this thesis, DFT is used to validate results from the GA regarding lithium-aluminum layered double hydroxide. Surface chemistry is more directly explored in the prediction of adsorbates on surfaces of lithiated nickel-manganese-cobalt oxide, a common cathode material in lithium-ion batteries. Surfaces are evaluated at the DFT+U level of theory, which reduces electron over-delocalization, and the energies of the surfaces both bare and with adsorbates are compared. By applying first-principles thermodynamics to predict system energies under varying temperatures and pressures, the behavior of these surfaces in experimental conditions is predicted to be mostly pristine and bare of adsorbates. For breadth, this thesis also presents an investigation of the electronic and optical properties of organic semiconductors via DFT and time-dependent DFT calculations

Advances in Postharvest Process Systems

This Special Issue presents a range of recent technologies and innovations to help the agricultural and food industry to manage and minimize postharvest losses, enhance reliability and sustainability, and generate high-quality products that are both healthy and appealing to consumers. It focuses on three main topics of food storage and preservation technologies, food processing technologies, and the applications of advanced mathematical modelling and computer simulations. This presentation of the latest research and information is particularly useful for people who are working in or associated with the fields of agriculture, the agri-food chain and technology development and promotion

The development of methods for the reproduction in continuous tone of digitally printed colour artworks

Advances in printing technologies in the late 19th century led to the development of half-toning techniques enabling the economical reproduction of photographic images in print. Whilst undoubtedly successful in low cost high volume image reproduction, half-toning representations are less faithful in detail when compared to continuous tone photomechanical methods in use at that time. This thesis asks the question: can the creative application of 21st century digital fabrication technologies enable the qualities of continuous tone imaging to be regained? In the 21st-century, printmaking may be seen as the interchange of ideas, experimental practice and interdisciplinary thinking. Printmaking has always been a means of combining modern technology and methods with existing traditional and commercial imaging processes. Technological advancement in print however does not always provide a finer quality of print. Qualities often attributed to pre-digital continuous tone printing can be lost in the transition to a digital half tone print workflow. This research project examines a near obsolete 19th century print process, the continuous tone Woodburytype, developed to address the issue of permanence in photography. Through a methodological approach analyses of the Woodburytype an empirical reconstruction of the process provides a comprehensive critique of its method. The Woodburytype’s surface qualities are not found in other photomechanical printing methods capable of rendering finely detailed photographic images. Its method of image translation results in the printed tonal range being directly proportional to the deposition thickness of the printing ink, however it never successfully developed into a colour process. By examining and evaluating digital imaging technology this study identifies, current computer aided design and manufacturing techniques and extends upon known models of Woodburytype printing through the development of this deposition height quality enabling a new digital polychromatic colour printing process

Hyperspectral colour imaging and spectrophotometric instrumentation

The trichromatic nature of commercial photography is strictly connected with the nature of human colour vision, although the characteristics of usual colour imaging devices are quite different from the human visual system. The increase in the number of colour channels for spectral (either multispectral or hyperspectral) imaging is an active field of research with many potential applications in different fields. Each element of the captured scene is specified in the spectral image by the spectral reflectance factor. This measurement is independent of the particular illumination of the scene and allows the colorimetric computation in a device-independent colour space for any chosen illuminant and any observer. This thesis describes the project and construction of a compact spectrophotometric camera, which can be used in both portable and in-situ applications. The compactness is made possible by a suitable image spectral scanning based on an Induced Transmission Filter (ITF). This filter is made by a set of thin-film coatings of dielectric materials with high and low refraction index, whose shape like a wedge induces a wavelength selective transmittance, continuously variable along one direction and uniform in the perpendicular direction. Such a filter, classified as Linearly Variable Filter (LVF), operates continuously from 430nm to 940nm and allows hyperspectral imaging. In traditional scanners the whole apparatus is moved along a path as long as the scene, whereas in this instrument the camera body is still and the LVF is the only moving part. The sequence of operations for wavelength and radiometric calibrations are discussed. The expected acquisition times and number of images as a function of the spectral sampling step are considered. The resulting properties make the instrument easy to use and with short acquisition times. Moreover, overviews of the historic evolution of colour vision fundamentals, colour spaces and spectral imaging technology are given for introducing the reader to the essential concepts useful for the understanding of the text