The digital world is acquiring more space in today’s society. With this being said, it is important to keep the web content interpretable for everyone, despite any kind of disability. This study focuses on colour vision deficiency and how to implement a real-time colour correction instantly in the web browser, without any additional assistive technologies needed. Two almost identical webpages have been developed for this project, with the difference being that one is with a colour correction function and one without, who then are measured in page-loading time to see if there is any greater loss of performance when executing the colour conversion.

With increasing demand placed on online accessibility, a tool that enables developers to more easily build accessible websites for colour vision deficient (CVD) internet users becomes a crucial consideration. An extension was developed for the web browser, Google Chrome, and issues for CVD internet users were identified. The identification was based on the luminance and colour contrast between different objects next to each other on a web page, such as fonts and their background. The extension calculated how a CVD internet user would experience the colours and then checked the contrast between them. The extension's calculations and reliability was assessed through a evaluation with CVD internet users and the results suggested that it would be possible to reliably detect issues related to CVD internet users with a algorithm implemented in a Chrome extension. / Med ökande krav på tillgänglighet på internet så ökar behovet av ett verktyg som underlättar för utvecklare att bygga hemsidor för personer med defekt färgseende. Ett tilläggsprogram utvecklades för webbläsaren Google Chrome, och problem för personer med defekt färgseende identifierades. Identifikationen baserades på luminanskontrast och färgkontrast mellan olika närliggande objekt på en hemsida, så som fonter och deras bakgrund. Tilläggsprogrammet beräknade hur en person med defekt färgseende upplever färgerna på hemsidan och kontrollerar kontrasten mellan dem. Tilläggsprogrammets tillförlitlighet bedömdes med hjälp av en utvärdering genomförd med personer med defekt färgseende. Utvärderingen indikerade att det är möjligt att tillförlitligt identifiera problem relaterade till personer med defekt färgseende med hjälp av en algoritm implementerad i ett Chrome tilläggsprogram.

In digital environments, colour is used for many purposes: for example, to encode information in charts, signify missing field information on websites, and identify active windows and menus. However, many people have inherited, acquired, or situationally-induced Colour Vision Deficiency (CVD), and therefore have difficulties differentiating many colours. Recolouring tools have been developed that modify interface colours to make them more differentiable for people with CVD, but these tools rely on models of colour differentiation that do not represent the majority of people with CVD. As a result, existing recolouring tools do not help most people with CVD. To solve this problem, I developed Situation-Specific Modelling (SSM), and applied it to colour differentiation to develop the Individualized model of Colour Differentiation (ICD). SSM utilizes an in-situ calibration procedure to measure a particular user’s abilities within a particular situation, and a modelling component to extend the calibration measurements into a full representation of the user’s abilities. ICD applies in-situ calibration to measuring a user’s unique colour differentiation abilities, and contains a modelling component that is capable of representing the colour differentiation abilities of almost any individual with CVD. This dissertation presents four versions of the ICD and one application of the ICD to recolouring. First, I describe the development and evaluation of a feasibility implementation of the ICD that tests the viability of the SSM approach. Second, I present revised calibration and modelling components of the ICD that reduce the calibration time from 32 minutes to two minutes. Next, I describe the third and fourth ICD versions that improve the applicability of the ICD to recolouring tools by reducing the colour differentiation prediction time and increasing the power of each prediction. Finally, I present a new recolouring tool (ICDRecolour) that uses the ICD model to steer the recolouring process. In a comparative evaluation, ICDRecolour achieved 90% colour matching accuracy for participants – 20% better than existing recolouring tools – for a wide range of CVDs. By modelling the colour differentiation abilities of a particular user in a particular environment, the ICD enables the extension of recolouring tools to helping most people with CVD, thereby reducing the difficulties that people with CVD experience when using colour in digital environments.

Four studies including ten experiments adresses interrelations between some major and classical issues in visual perception: 3-D perception, colour constancy, colour perception and colour vision deficiencies. The main experimental paradigm to investigate the issues is within that of simulated shape from shading. 3-D impressions are induced by projecting space-modulated illuminations onto flat surfaces (displays), varying the colours and layout of the displays and the colour and modulation of the illumination. Study I includes four experiments investigating three types of space- modulated illumination. All experiments confirmed earlier findings that chromatic colour and complex display layout with reflectance edges crossed by illumination edges enhances shape from shading. In Study II the impressions of shape from shading and real 3-D objects were compared between persons with deutan colour vision deficiencies and normals. As predicted, the deutans show fewer and less distinct 3-D impressions in situations with their specific "problem colours" red and green. They also show a generally lower tendency for 3-D impressions, interpreted as a generally weaker colour constancy. Study III presents the AMBEGUJAS phenomenon; a novel twofold ambiguous shape from shading situation, continuously alternating between two different 3-D impressions coupled with different colour attributions. One solution is of an object with two clear surface colours, the other one of an object with greyish (desaturated) colours in coloured illumination which means classical colour constancy. The phenomenon illustrates the visual processes of separating reflectance and illumination characteristics and may provide a useful experimental setting to study colour constancy. In Study IV the AMBEGUJAS phenomenon is found to be robust as to chromaticness and different luminance contrasts for both normals and deutans. However, the deutans show slower shifts between percepts and a less pronounced desaturation of colour, which indicates a weaker colour constancy. The studies add evidence to the contribution of colour to 3-D shape perception, validated in a novel way by the results on "colour-blinds". The AMBEGUJAS phenomenon provides further support that the factors affecting shape from shading and the deutans different impressions are to be understood with reference to colour constancy. The deutans different impressions compared to normals are remarkable per se, but probably with very limited implications to everyday life. / <p>Diss. (sammanfattning) Umeå : Umeå university, 1996, härtill 4 uppsatser</p> / digitalisering@umu

Purpose WCAG is a set of guidelines to assist in developing websites accessible for everyone, for example people with colour vision deficiency (CVD). However, there are few guidelines relevant for CVD and with increasing dependant on websites the importance of accessibility on these websites increases as well. The purpose of the research study is therefore to investigate the impact the relevant guidelines for CVD in WCAG 2.1 has on Swedish health care websites and what the consequences are for people who live with CVD. Method An initial literature study was conducted to gain knowledge of previous findings and also evaluate the best approach for the research study. The research study is based on a qualitative approach to gain a deep understanding of the area and to gain insight into the feelings and experiences of the people affected. The methods used to gain the necessary knowledge are an evaluation of 1177.se and e-tjanster.1177.se also observations and interviews around these two websites. Findings The results show that WCAG 2.1 has a positive impact on Swedish health care websites, as well as on users with CVD. From evaluations, interviews and observations it is concluded that 1177.se and e-tjanster.1177.se are easy to perceive for people with CVD. Implications This research study was limited to the mobile version of the websites. However, the results could be different if the research was conducted on the desktop version due to the different structure of the websites and the inclusion of a cursor on desktop. The evaluation could have been affected by the sampling of pages while the interviews and observations should not have been. Limitations The research study was limited to Swedish health care website 1177.se and its subdomain etjanster. 1177.se. Further it was decided to evaluate the mobile version of these websites, although the elements should look similar on desktop and mobile. While not the initial intention, due to over representation of red-green CVD the study was also limited to people with red-green CVD. Also, the experience of browsing the web on a mobile device was considered to reduce the variables for frustrations. Further research For further research, another selection of WCAG guidelines could be considered to evaluate etjanster. 1177.se since the results shows that 1177.se’s and e-tjanster.1177.se's weaknesses seems to be in the structure of the website. A study researching the “blue-yellow colour blindness” compared to websites could contribute with new, relevant knowledge as well.