Color space analysis for iris recognition

This thesis investigates issues related to the processing of multispectral and color infrared images of the iris. When utilizing the color bands of the electromagnetic spectrum, the eye color and the components of texture (luminosity and chromaticity) must be considered. This work examines the effect of eye color on texture-based iris recognition in both the near-IR and visible bands. A novel score level fusion algorithm for multispectral iris recognition is presented in this regard. The fusion algorithm - based on evidence that matching performance of a texture-based encoding scheme is impacted by the quality of texture within the original image - ranks the spectral bands of the image based on texture quality and designs a fusion rule based on these rankings. Color space analysis, to determine an optimal representation scheme, is also examined in this thesis. Color images are transformed from the sRGB color space to the CIE Lab, YCbCr, CMYK and HSV color spaces prior to encoding and matching. Also, enhancement methods to increase the contrast of the texture within the iris, without altering the chromaticity of the image, are discussed. Finally, cross-band matching is performed to illustrate the correlation between eye color and specific bands of the color image

A Study of the color management implementation on the RGB-based digital imaging workflow: digital camera to RGB printers

An RGB (red, green, and blue color information) workflow is used in digital photography today because a lot of the devices digital cameras, scanners, monitors, image recorders (LVT or Light Value Technology), and some types of printers are based on RGB color information. In addition, rapidly growing new media such as the Internet and CD-ROM (Compact Disc-Read-Only Memory) publishing use an RGB -based monitor as the output device. Because color is device-dependent, each device has a different method of representing color information. Each has a different range of color they can reproduce. Most of the time, the range of color, color gamut, that devices can produce is smaller than that of the original capturing device. As a result, a color image reproduction does not match accurately with its original. Therefore, in typical color image reproduction, the task of matching a color image reproduction with its original is a significant problem that operators must overcome to achieve good quality color image reproduction. Generally, there are two approaches to conquer these problems. The first method is trial-and-error in the legacy-based system. This method is effective in a pair-wise working environment and highly depended on a skill operator. The second method is the ICC-based (ICC or International Color Consortium) color management system (CMS) which is more practical in the multiple devices working environment. Using the right method leads to the higher efficiency of a digital photography produc tion. Therefore, the purpose of this thesis project is to verify that ICC-based CMS with an RGB workflow has higher efficiency (better utilized of resource and capacity) than a legacy-based traditional color reproduction workflow. In this study, the RGB workflows from digital cameras to RGB digital printers were used because of the increasing num ber of digital camera users and the advantages of using an RGB workflow in digital pho tography. There were two experimental image reproduction workflows the legacy-based system and the ICC-based color management system. Both of them used the same raw RGB images that were captured from digital cameras as their input files. The color images were modified with two different color matching methods according to each workflow. Then, they were printed out to two RGB digital printers. Twenty observers were asked to evaluate the picture quality as well as the reproduction quality. The results demonstrated that the two workflows had the ability to produce an accept able picture quality reproduction. For reproduction quality aspect, the reproductions of the ICC-based CMS workflow had higher reproduction quality than the legacy-based workflow. In addition, when the time usage of the workflow was taken into account, it showed that the ICC-based CMS had higher efficiency than the legacy-based system. However, many times, image production jobs do not start with optimum quality raw images as in this study; for example, they are under/over exposure or have some defects. These images need some retouching work or fine adjustment to improve their quality. In these cases, the ICC-based CMS with skilled operators can be implemented to these types of production in order to achieve the high efficiency workflow

ColrSpace: A Mata class for color management

ColrSpace is a class-based color management system implemented in Mata. It supports a wide variety of color spaces and translations among them, provides color generators and a large collection of named palettes, and features functionality such as color interpolation, grayscale conversion, or color vision deficiency simulation. ColrSpace requires Stata 14.2 or newer

Analysis of Low-Cost Color Sensor Device Performance as Compared to Standardized Spectrophotometers

This work presents the process of assessing and selecting a low-cost color sensor suitable for illustrating essential concepts within pre-established graphic communications curricula for virtual learning. The suitability of the device was determined based on its ability to evaluate concepts presented in the curriculum, such as the whiteness and opacity of the substrates, and the optical density, tone reproduction, color balance, hue error, grayness, and overprint trapping of inks. The initial testing and data collected from the virtual classroom indicates statistically significant differences between the low-cost device and X-Rite eXact; however, the concept illustration was not impeded by the differences. After initial success implementing a color sensor into the virtual classroom, further research was performed to evaluate the devices’ ability to obtain repeat measurements (repeatability and reproducibility) and its accuracy (or ability to conform to accepted values for a given printed sample) using the MCDM (mean color difference form mean) and Zc (Z-score of color) methods for evaluating color difference. In this research, the values collected using low-cost color sensors were compared to those from a standard device, X-Rite eXact. This work accepts the values collected by the X-Rite eXact as true and considers them to be accepted values for the given printed sample

N-colour separation methods for accurate reproduction of spot colours

In packaging, spot colours are used to print key information like brand logos and elements for which the colour accuracy is critical. The present study investigates methods to aid the accurate reproduction of these spot colours with the n-colour printing process. Typical n-colour printing systems consist of supplementary inks in addition to the usual CMYK inks. Adding these inks to the traditional CMYK set increases the attainable colour gamut, but the added complexity creates several challenges in generating suitable colour separations for rendering colour images. In this project, the n-colour separation is achieved by the use of additional sectors for intermediate inks. Each sector contains four inks with the achromatic ink (black) common to all sectors. This allows the extension of the principles of the CMYK printing process to these additional sectors. The methods developed in this study can be generalised to any number of inks. The project explores various aspects of the n-colour printing process including the forward characterisation methods, gamut prediction of the n-colour process and the inverse characterisation to calculate the n-colour separation for target spot colours. The scope of the study covers different printing technologies including lithographic offset, flexographic, thermal sublimation and inkjet printing. A new method is proposed to characterise the printing devices. This method, the spot colour overprint (SCOP) model, was evaluated for the n-colour printing process with different printing technologies. In addition, a set of real-world spot colours were converted to n-colour separations and printed with the 7-colour printing process to evaluate against the original spot colours. The results show that the proposed methods can be effectively used to replace the spot coloured inks with the n-colour printing process. This can save significant material, time and costs in the packaging industry

The development of multi-channel inkjet printing methodologies for fine art applications

This thesis contributes to the defence of the practitioner perspective as a means of undertaking problems addressed predominantly in the field of colour science. Whilst artists have been exploring the use of colour for centuries through their personal practice and education, the rise of industrialised printing processes has generated a shift in focus away from these creative pursuits and into the computational field of colour research. It is argued here that the disposition and knowledge generated by creative practice has significant value to offer developing technologies. While creative practice has limited influence in the development of colour printing, practitioners and users of technology actively engage with the process in ways that extend beyond its intended uses in order to overcome recognised shortcomings. Here consideration is given to this creative engagement as motivation to develop bespoke printing parameters that demonstrate the effects of colour mixing through methods alternative to standard workflows. The research is undertaken incorporating both qualitative and quantitative analysis, collecting data from visual assessments and by examining spectral measurements taken from printed output. Action research is employed to directly access and act upon the constant developments in the art and science disciplines related to inkjet printing, observing and engaging with current methods and techniques employed by practitioners and developers. This method of research has strongly informed the empirical testing that has formed this thesis’s contribution to fine art inkjet printing practice. The research follows a practitioner led approach to designing and testing alternative printing methods and is aimed at expanding the number of discernible colours an inkjet printer can reproduce. The application of this methodology is evidenced through demonstrative prints and a reproduction study undertaken at the National Gallery, London. The experimentation undertaken in partnership with the National Gallery has proven the ability to increase accuracy between colour measured from the original target and reproduction, beyond the capabilities of current inkjet printing workflows

Between physics and art: Imaging the un-image-able

This thesis explores the ways in which art practice can engage with science, and more precisely, how my own practice interacts with scientific knowledge. The theoretical underpinning and contextual position of the practice make it particularly suited to explore the concept of visuality, here deployed as a shared notion between scientific and artistic production. The artwork testifies to a deep interest in and fascination with the latest research in physics and the complex problems associated with the aesthetic visualisation of scientific concepts related to extreme scale, distance and mathematical abstraction. Through two volumes (a written thesis and supporting material) and an exhibition of artworks, the research asks: how can meaning be translated, transformed, and transfigured between one domain (science) and another (art), using the visual as its mode of mediation?Following an opening survey of the broader field of investigation, looking at past and present literature and practices in the realm of science and art, the thesis analyses my art practice (considered as a hybrid between graphic design, illustration and visual communication) in terms of its immediate context, underlying motivations and methods for the production of art. In its present form, my practice does not fit any of the current sub-domains identified in the landscape of contemporary art, and is often situated outside the dialogues and concerns of fellow practitioners. Nor does it fully belong to the realm of scientific visuality (or of an “aestheticised science”): the field has shown some limitations in relation to art’s own domain of images, where modes of practice are not shared. In this instance the art is often reduced to explaining and communicating science in visual form. In contrast, my practice deploys a more sophisticated engagement with its referent, which needs to be positioned in relation to other practices, and its wider field of enquiry. To address this issue, findings from the initial investigation are reintroduced in order to conduct a reflective analysis through which the practice – argued as distinctive, and yet related to other visual traditions – exposes the problems that exist in the loosely defined domain of “Art and Science”.Taking the position of the reflective practitioner, the thesis demonstrates how the notion of research is intrinsically embedded in the creative process; therefore the enquiry also argues for the production of artworks as artistic research. Through the formation of a three-fold proposition – a method-practice-discourse – the investigation shows how this body of work can participate in, and question, the dominant dialogues in Art and Science. Furthermore, it serves to revisit the conventional views in the study of visuality by articulating an alternative form of engagement between two otherwise specialist domains. Ultimately, the research presents its proposition as a contribution to knowledge by providing a model for both practitioners and scholars