Papers by Stephen Westland
Itten, Johannes
Encyclopedia of Color Science and Technology
Our evolving hypothesis is that a colour-picker interface designed to challenge the novice user w... more Our evolving hypothesis is that a colour-picker interface designed to challenge the novice user will better connect with their creative abilities and help develop their understanding of the interrelated digital colour challenges. An interface approach underpinned by a philosophy of engaging-in-use rather than ease-of-use may help to better rationalize a new user’s colour-selection process, thus improving their initial productivity and creativity within the digital design environment. This study challenges the established HCI (Human Computer Interaction) convention that consistently prescribes to a user-interface-strategy embracing ease-of-use. It considers if this ideal is necessarily the right approach for creative software application, assessing colour-pickers as the primary example. Interesting results are emerging from experimental work with an early prototype colour-picker tool that exploits our ongoing research into intuitive understanding of colour. The focus of this work is ...
It is known that colours evoke memories and emotions and that these associations are valuable in ... more It is known that colours evoke memories and emotions and that these associations are valuable in design. However, it is difficult to ascertain universal associations because often the word-colour associations are cultureand context-specific. Nevertheless, some important universal colour associations have been shown to exist, at least if the variable of culture is removed. Laboratory studies, however, although effective struggle to collect sufficient information to allow the data to be useful in a practical setting. In this study, a crowd-sourcing internet experiment was carried out to find colours that are associated with different words and the results were compared with those from a previous laboratory study. Approximately 150 participants made a total of 1350 word-colour associations to generate palettes for 30 target words. Comparison with corresponding data from the laboratory study suggests that crowd-sourcing is a promising route and should be explored further.
International Journal of Environmental Research and Public Health
(1) Background: The harm of misusing over-the-counter (OTC) codeine-containing medicines among un... more (1) Background: The harm of misusing over-the-counter (OTC) codeine-containing medicines among university students in England is being increasingly recognized. Based on English university students, this paper aims to study the importance of information design on information communication, explore methods for effective warning design, and investigate university students' perception of OTC codeine. (2) Methods: The effective warning design is addressed through case studies, answering correctness by the heat map generated from the eye-tracking experiment (ETE), and the total time spent on the tasks. User perceptions are made though online surveys. (3) Results: Information design significantly affects the way user processes information. Therefore, two emphasized warnings displayed in the headline, and the "possible side effect (PSE)" sections and warning signs of addiction presented under the PSE are suggested as effective ways to display warnings. For students' perception of OTC codeine, 80% of university students are unfamiliar with the substance. After reading the patient information leaflets (PILs), 47% recommended tight regulation on codeine. (4) Conclusions: The misuse of OTC codeine could be a potential problem among English university students. The design of the PIL significantly influences the chance of unintentional medicine misuse. The display of warnings on the PILs of OTC codeine should be redesigned for better understanding.
Wiley-IS&T Series in Imaging Science and Technology
CMYK Systems
Handbook of Visual Display Technology, 2012
Color Communication
Handbook of Visual Display Technology, 2012
Behavioral Sciences
The purpose of this study was to explore the influence of environmental colour on people’s latera... more The purpose of this study was to explore the influence of environmental colour on people’s lateral and logical abilities. This was done by evaluating study participants’ response time and error rate when completing six types of psychometric tests that were performed in various hue backgrounds on a computer. To maximise the colour stimulation provided by the monitor, the experiment was carried out in a dark laboratory. Analysis of participants’ response time and error rate showed that different colours could significantly influence arousal and impulsiveness, which suggests that colour has indirect impacts on cognitive abilities. Further analysis revealed that different colours had various effects depending on the type of psychometric test given. These findings suggest that future research on environmental design should consider how to effectively use colour to impact people’s performance and behaviour.
Journal of dentistry, 2017
To assess the robustness of a new custom built video-based digital imaging system (VDIS) for meas... more To assess the robustness of a new custom built video-based digital imaging system (VDIS) for measuring tooth colour and whiteness under in vitro and in vivo conditions. The VDIS imaging system was developed for tooth colour measurement and evaluated in vitro and in vivo. The in vitro validation used extracted human teeth (HT, n=14) stored in water and VITA Classical shade guide tabs (SG, n=16). These were measured by the VDIS at baseline, 5min, 2h, 1 week and 2 weeks to evaluate the system repeatability. For in vivo validation, adult volunteers (male/female, n=34) with two natural, unrestored central incisors had their teeth imaged using the VDIS at baseline, 5min and 2h (3 images each) by two different operators to evaluate time and operator effects. Between taking individual images, subjects moved from the imaging-frame to assess the effect of re-positioning on reproducibility. From the in vitro and in vivo images, the average tooth RGB values were obtained, and the CIELAB values ...
Journal of dentistry, 2017
To investigate the tooth whiteness perceptibility thresholds of the average observer to changes i... more To investigate the tooth whiteness perceptibility thresholds of the average observer to changes in the CIELAB values and an optimised whiteness Index for dentistry (WIO) based on psychophysical studies. A psychophysical experiment based on visual assessments of digital images of teeth on a calibrated display with a group of observers (n=32) has been conducted to determine the perceptual thresholds in tooth whiteness. Digital simulations of a tooth that is identical in shape to the left incisor in the image of teeth were superimposed on to images. The colour of the simulated tooth was varied and observers were asked to respond whether there was a difference in whiteness between the left incisor and the simulated tooth. Thresholds for detection of differences in whiteness were independently determined in four conditions: ΔL*, Δa*, Δb* and a blue optical whitening direction. Raw data were fitted using a non-parametric approach and thresholds of CIELAB and WIO for each conditions were c...
Color spaces for discrimination and categorization in natural scenes
Physical measurements of surfaces' color-causing properties are typically spectroradiometric... more Physical measurements of surfaces' color-causing properties are typically spectroradiometric, whereas color-differencing comparisons are typically colormetric ones performed in some 3-D color space. In general, this downprojection of high-dimensional spectral ...
Uncertainties in Tooth Colour Measurement using Digital Camera
ABSTRACT
Color naming transitions
ABSTRACT We explore the notion that variations in cone spectral sensitivities could cause variati... more ABSTRACT We explore the notion that variations in cone spectral sensitivities could cause variations in color-name boundaries between individuals. Fifteen observers made color matches to a test stimulus (580 nm) with three primary lights in a visual colorimeter. The same observers took part in two psychophysical experiments to determine the color-naming boundary between two focal colors (yellow and green). In one experiment observers used a slider bar to indicate the boundary; in the other they were presented with a color stimulus and asked to state whether it was yellow or green in a 2afc design. In the case of the 2afc experiment the results indicate some evidence to suggest a correlation in the position of the name boundary and the ratio of red and green lights used in visual color matches.
A Novel Method for Representation of Spectral Images Based on Color Matching Functions
Advanced Materials Research, Mar 18, 2011
Spectral images contain a large volume of data and the development of multispectral imaging syste... more Spectral images contain a large volume of data and the development of multispectral imaging systems places considerable demands on computer hardware and software compared with standard three-component or trichromatic image storage and processing. This study is concerned with lossy compression techniques for spectral images since many color images are intended for display for human perception and it is well established that images contain redundancies (in terms of their color, spatial and temporal properties) that can be removed without any loss in image quality. The lossy compression technique that is considered in this work is a low-dimensional linear model of spectral reflectance, with which the basis function are derived from color matching functions that are correlated with human visual system.
Characterization of Cameras
Analysis of Hyperspectral Images Based on PCA
Advanced Materials Research, Mar 31, 2011
Recent computational models of color vision demonstrate that it is possible to achieve exact colo... more Recent computational models of color vision demonstrate that it is possible to achieve exact color constancy over a limited range of lights and surfaces described by a low-dimensional linear model. For smooth reflectance spectra the different spectral bands have a significant degree of correlation. Any spectral reflectance distribution can be approximated to a specified degree of accuracy as a weighted sum of basis functions. Reflectance spectra of hyperspectral images of the natural scenes are supposed to represent the real world better than any certain classes of natural and man-made spectral reflectance data sets such as rocks, leaves, Munsell chips, etc. The characteristics of the spectra will be important to understand the spectral properties of the object reflectance and the representation of spectral images by linear models. In this study sets of hyperspectral images have been analyzed by principal-component analysis (PCA) method for spectral encoding.
Measurement of Perceived Brightness and Contrast Sensitivity for Outdoor Condition
Page 1. YJ Kim , Measurement of Perceived Brightness and Contrast Sensitivity for Outdoor Conditi... more Page 1. YJ Kim , Measurement of Perceived Brightness and Contrast Sensitivity for Outdoor Condition 1 MEASUREMENT OF PERCEIVED BRIGHTNESS AND CONTRAST SENSITIVITY FOR OUTDOOR CONDITION Youn Jin ...
Conversion between CIELAB and Munsell Hue
This study is a preliminary investigation towards the design of effective colour spaces and colou... more This study is a preliminary investigation towards the design of effective colour spaces and colour tools to allow users to quickly and accurately select a given colour in a digital-display environment. It has been shown that many non-expert users find the RGB colour space to be non- intuitive. The choice of colour space on various visual tasks has also been
Application of Neugebauer Models to Ceramic Printing
Color Imaging Conference, 2004
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Papers by Stephen Westland