Navigating the roadblocks to spectral color reproduction: data-efficient multi-channel imaging and spectral color management

Commercialization of spectral imaging for color reproduction will require the identification and traversal of roadblocks to its success. Among the drawbacks associated with spectral reproduction is a tremendous increase in data capture bandwidth and processing throughput. Methods are proposed for attenuating these increases with data-efficient methods based on adaptive multi-channel visible-spectrum capture and with low-dimensional approaches to spectral color management. First, concepts of adaptive spectral capture are explored. Current spectral imaging approaches require tens of camera channels although previous research has shown that five to nine channels can be sufficient for scenes limited to pre-characterized spectra. New camera systems are proposed and evaluated that incorporate adaptive features reducing capture demands to a similar few channels with the advantage that a priori information about expected scenes is not needed at the time of system design. Second, proposals are made to address problems arising from the significant increase in dimensionality within the image processing stage of a spectral image workflow. An Interim Connection Space (ICS) is proposed as a reduced dimensionality bottleneck in the processing workflow allowing support of spectral color management. In combination these investigations into data-efficient approaches improve two critical points in the spectral reproduction workflow: capture and processing. The progress reported here should help the color reproduction community appreciate that the route to data-efficient multi-channel visible spectrum imaging is passable and can be considered for many imaging modalities

Sensor Array-Based Optical Portable Instrument For Determination Of Ph

A portable optical instrument is presented that makes it possible to determine pH with a colorimetric sensor array. The use of four membranes containing acid-base indicators makes it possible to cover the full range of pH using the H (hue) coordinate measurements of the HSV colour space. pH sensitive membranes were directly cast onto a plastic support to form a two-dimensional array, located between an OLED display as the programmable light source and a set of digital colour detectors. The resulting microcontroller-based system is immune to optical and electrical interferences. A complete optical and electrical characterization and optimization of the hand-held instrument was carried out. The instrument was used to determine pH using a simple algorithm to select the sensor output that was programmed in the microcontroller. The initial eleven candidate pH membranes were reduced to only four, which permit to obtain reliable pH values. The pH response of the selected four sensing elements was modelled, and calibration curves were applied to a validation set and real samples obtaining positive correlations between the real and predicted data.Ministerio de Ciencia e Innovación, Dirección General de Investigación y Gestión del Plan Nacional de I+D+i (Spain) (Projects CTQ2009-14428-C02-01 and CTQ2009-14428-C02-02)Junta de Andalucía (Proyecto de Excelencia P08-FQM-3535)Partially supported by European Regional Development Funds (ERDF

The development and optimisation of a novel microfluidic immunoassay platform for point of care diagnostics

Protein biomarkers are important diagnostic tools for detection of non-communicable diseases, such as cancer and cardiovascular conditions. In order to be used as diagnostic tools they need to be detected at very low concentrations in biological samples (e.g. whole blood, serum or urine). This has been currently performed in central laboratories using expensive, bulky equipment and time consuming assays. [Continues.

SURFACE-INITIATED POLYMERIZATIONS FOR THE RAPID SORTING OF RARE CANCER CELLS

Cancer metastasis directly accounts for an estimated 90% of all cancer related deaths and is correlated with the presence of malignant cells in systemic circulation. This observed relationship has prompted efforts to develop a fluid biopsy, with the goal of detecting these rare cells in patient peripheral blood as surrogate markers for metastatic disease as a partial replacement or supplement to tissue biopsies. Numerous platforms have been designed, yet these have generally failed to support a reliable fluid biopsy due to poor performance parameters such as low throughput, low purity of enriched antigen positive cells, and insufficiently low detection thresholds to detect poor expressed surface markers of target cell populations. This work describes the development of a rapid cell sorting technology called Antigen Specific Lysis (ASL) based on photo-crosslinked polymer encapsulation to isolate tumor cells in suspension. In the first study, we characterize the chemical and structural properties of the surface-initiated polymer films formed directly on mammalian cell surfaces. Coated populations are shown to remain highly viable after coating formation. Biomolecular transport is examined though film coatings on cellular substrates using fluorescent, time-resolved confocal microscopy and diffusivity estimates are generated for these materials. In the next study, a lysis-based cell isolation platform is described in which marker positive cells can be specifically coated in a heterogeneous cell suspension. Anionic surfactants lyse virtually 100% of uncoated cells while fully encapsulated cells remain protected, and are then easily collected by centrifugation. We report that purified cells are released from polymeric coatings to yield viable and functional populations. We monitor cell response throughout the isolation process by multiple techniques, and report viability \u3e80% after the sorting process. Lastly, we examine the response of process yield on the level of photoinitiator loading on target populations. Streptavidin-fluorochrome loading was quantitatively assessed on a panel of markers, both epithelial and mesenchymal, on representative model breast and lung cancer cells. We report that ASL is fundamentally capable of achieving 50-60% yield which is promising for fluid biopsy applications. Finally, both EpCAM and metastatic targeting strategies are then compared to covalently biotinylated samples to inform future robust targeting strategies

Expanding Dimensionality in Cinema Color: Impacting Observer Metamerism through Multiprimary Display

Television and cinema display are both trending towards greater ranges and saturation of reproduced colors made possible by near-monochromatic RGB illumination technologies. Through current broadcast and digital cinema standards work, system designs employing laser light sources, narrow-band LED, quantum dots and others are being actively endorsed in promotion of Wide Color Gamut (WCG). Despite artistic benefits brought to creative content producers, spectrally selective excitations of naturally different human color response functions exacerbate variability of observer experience. An exaggerated variation in color-sensing is explicitly counter to the exhaustive controls and calibrations employed in modern motion picture pipelines. Further, singular standard observer summaries of human color vision such as found in the CIE’s 1931 and 1964 color matching functions and used extensively in motion picture color management are deficient in recognizing expected human vision variability. Many researchers have confirmed the magnitude of observer metamerism in color matching in both uniform colors and imagery but few have shown explicit color management with an aim of minimized difference in observer perception variability. This research shows that not only can observer metamerism influences be quantitatively predicted and confirmed psychophysically but that intentionally engineered multiprimary displays employing more than three primaries can offer increased color gamut with drastically improved consistency of experience. To this end, a seven-channel prototype display has been constructed based on observer metamerism models and color difference indices derived from the latest color vision demographic research. This display has been further proven in forced-choice paired comparison tests to deliver superior color matching to reference stimuli versus both contemporary standard RGB cinema projection and recently ratified standard laser projection across a large population of color-normal observers

Colorimetric sensor arrays for the detection of aqueous and gaseous analytes

The past decade has seen great interest concerning the development of artificial sensing devices; most notably optoelectronic tongues and noses. Utilizing previous research on how the mammalian gustatory and olfactory systems operate, significant progress in mimicking these systems has been realized. The turning point in this field of research has been the discovery that the mammalian senses of smell and taste are not based on specific receptors for each stimulant, but rather an array of semi-specific receptors that function simultaneously to produce a pattern. This pattern is interpreted in the brain, and classified either as a known stimulant or a new analyte similar to a known family of tastes or odors. As a predominantly visual species, we are programmed to acknowledge visible reports to chemical reactions over alternative reporting methods. Thus, colorimetric sensing can be more advantageous than other techniques and can allow for a greater number of chemical reactions to be probed. One colorimetric approach to sensing involves the immobilization of cross-responsive chemosensors capable of showing a color change upon reaction with analytes or mixtures of analytes. The employment of porous glasses as an immobilization technique has allowed for facile detection of analytes, both aqueous and gaseous, by allowing dye-analyte interactions to occur while preventing the sensor dye from escaping from the matrix. In this manner, colorimetric sensor arrays have been fashioned that are capable of discriminating among structurally similar compounds such as sugars, while retaining the ability to detect a wide range of analytes including toxic industrial chemicals. For aqueous detection, the newly developed porous glasses successfully immobilized otherwise soluble dyes that could detect changes in solution pH, caused by boronic acid-diol interactions. This allowed for rapid and sensitive detection and identification of natural and artificial sugars and sweeteners. Further experiments showed the array’s ability to differentiate between a selection of common table-top sweeteners such as Equal®, Sweet’N’Low®, Splenda®, and natural sugars. Gas sensing applications were made possible by slight modifications to the liquid sensing array. Hydrophobic silica precursors were added to limit the effect of changing humidity on the array, and printing onto flat, non-porous polymer surfaces gave fast and easy accessibility of incoming analytes to the immobilized indicators. Stable and sensitive colorimetric arrays for the detection and semi-quantification of a large number of toxic industrial chemicals was made possible by the inclusion of additional indicators capable of colorimetrically reporting changes in polarity, metal ligation, and redox reactions. The performances of these sensing arrays showed extremely low limits of detection, and were capable of identifying toxic gases within a large range of concentrations; ppb up to concentration immediately dangerous to life and health. In order to improve upon the detection limits for weakly responding gaseous analytes, alternative methods were developed. It was found that the immobilization of simple and stable color-changing dyes within chemically-reactive matrices could allow for facile and sensitive detection and quantification of formaldehyde. Optimization studies were carried out to assess the proper doping level of hydrophilic polymers with amine-appended polyethylene glycol

The development of microfluidic paper-based analytical devices for point-of-care diagnosis of sheep scab

The recent growing interest and development of microfluidic paper-based analytical devices (μPADs) for point-of-care (POC) testing in human health in low-resource settings has great potential for the exploitation of these technologies in animal disease diagnosis. Sheep scab is a highly infectious, widespread and notifiable disease of sheep, which poses major economic and welfare concerns for the UK farming industry. The possibility of diagnosing sheep scab at the POC is, consequently, very important to controlling this disease. The overall aim of this project was, therefore, to develop μPADs based on a novel method of fabrication, in order to translate the existing lab-based sheep scab ELISA (Pso o 2) and a biomarker test for haptoglobin (Hp) into paper-based ELISA (P-ELISA), to enable POC diagnosis of this animal disease. In Chapter 3, the novel fabrication method is described, in Chapters 4 and 5, the translation of the lab-based ELISAs (Hp and Pso o 2 respectively) are explained and in Chapter 6 the development of a μPAD for incorporation of the POC tests into a multiplexed, rapid assay is covered. Experiments showed that both ELISAs were successfully transferred onto paper and that the devices developed were suitable for POC testing. This study has resulted in a novel fabrication method for μPADs, in successfully translated existing ELISAs to P-ELISA and in novel solutions for the POC diagnosis of an important veterinary disease

The development of microfluidic paper-based analytical devices for point-of-care diagnosis of sheep scab

The recent growing interest and development of microfluidic paper-based analytical devices (μPADs) for point-of-care (POC) testing in human health in low-resource settings has great potential for the exploitation of these technologies in animal disease diagnosis. Sheep scab is a highly infectious, widespread and notifiable disease of sheep, which poses major economic and welfare concerns for the UK farming industry. The possibility of diagnosing sheep scab at the POC is, consequently, very important to controlling this disease. The overall aim of this project was, therefore, to develop μPADs based on a novel method of fabrication, in order to translate the existing lab-based sheep scab ELISA (Pso o 2) and a biomarker test for haptoglobin (Hp) into paper-based ELISA (P-ELISA), to enable POC diagnosis of this animal disease. In Chapter 3, the novel fabrication method is described, in Chapters 4 and 5, the translation of the lab-based ELISAs (Hp and Pso o 2 respectively) are explained and in Chapter 6 the development of a μPAD for incorporation of the POC tests into a multiplexed, rapid assay is covered. Experiments showed that both ELISAs were successfully transferred onto paper and that the devices developed were suitable for POC testing. This study has resulted in a novel fabrication method for μPADs, in successfully translated existing ELISAs to P-ELISA and in novel solutions for the POC diagnosis of an important veterinary disease

Image segmentation and pigment mapping of cultural heritage based on spectral imaging

The goal of the work reported in this dissertation is to develop methods for image segmentation and pigment mapping of paintings based on spectral imaging. To reach this goal it is necessary to achieve sufficient spectral and colorimetric accuracies of both the spectral imaging system and pigment mapping. The output is a series of spatial distributions of pigments (or pigment maps) composing a painting. With these pigment maps, the change of the color appearance of the painting can be simulated when the optical properties of one or more pigments are altered. These pigment maps will also be beneficial for enriching the historical knowledge of the painting and aiding conservators in determining the best course for retouching damaged areas of the painting when metamerism is a factor. First, a new spectral reconstruction algorithm was developed based on Wyszecki’s hypothesis and the matrix R theory developed by Cohen and Kappauf. The method achieved both high spectral and colorimetric accuracies for a certain combination of illuminant and observer. The method was successfully tested with a practical spectral imaging system that included a traditional color-filter-array camera coupled with two optimized filters, developed in the Munsell Color Science Laboratory. The spectral imaging system was used to image test paintings, and the method was used to retrieve spectral reflectance factors for these paintings. Next, pigment mapping methods were brought forth, and these methods were based on Kubelka-Munk (K-M) turbid media theory that can predict spectral reflectance factor for a specimen from the optical properties of the specimen’s constituent pigments. The K-M theory has achieved practical success for opaque materials by reduction in mathematical complexity and elimination of controlling thickness. The use of the general K-M theory for the translucent samples was extensively studied, including determination of optical properties of pigments as functions of film thickness, and prediction of spectral reflectance factor of a specimen by selecting the right pigment combination. After that, an investigation was carried out to evaluate the impact of opacity and layer configuration of a specimen on pigment mapping. The conclusions were drawn from the comparisons of prediction accuracies of pigment mapping between opaque and translucent assumption, and between single and bi-layer assumptions. Finally, spectral imaging and pigment mapping were applied to three paintings. Large images were first partitioned into several small images, and each small image was segmented into different clusters based on either an unsupervised or supervised classification method. For each cluster, pigment mapping was done pixel-wise with a limited number of pigments, or with a limited number of pixels and then extended to other pixels based on a similarity calculation. For the masterpiece The Starry Night, these pigment maps can provide historical knowledge about the painting, aid conservators for inpainting damaged areas, and digitally rejuvenate the original color appearance of the painting (e.g. when the lead white was not noticeably darkened)