Nektarios Paisios: A Graduate of the Ph.D. Program in Computer Science

I am interested in the ways that computer technologies can be used to open new horizons to people with disabilities and especially the visually impaired. Even as a great number of the benefits of information technology have been realized, easily demonstrated by the fact that every business and every household is today actively using personal computers, or by the fact that a cell phone is present in every pocket, new avenues of discrimination have been created. Letters on some cell phone screens are still too tiny to be read by the partially sighted or by the elderly. Many software applications and websites essential for the modern everyday life are inaccessible to the totally blind. On the contrary, computing technologies have enabled the creation of a new class of software applications which can empower the visually impaired to overcome numerous difficulties which they had been facing for centuries. These include screen reading software which can read aloud, using synthetic speech, the contents of the computer's screen, or cell phone software which can take a picture and then read aloud pages of printed text, such as a restaurant menu.

Research Interests

  1. Accessibility and Computer Technologies: Research on how to remove the discrimination created by inaccessible mainstream software and how to empower the visually impaired by developing new assistive software solutions.
  2. Mobile Phone Assistive Software Development: Research on how to develop assistive software that takes advantage of the vast processing power and multitude of high-accuracy sensors (e.g. accelerometers and Wi-Fi receivers) found on modern smart phones.

Ph.D. Dissertation

Title: Mobile Accessibility Tools for the Visually Impaired


Visually impaired individuals are a growing segment of our population. However, social constructs are not always designed with this group of people in mind, making the development of better electronic accessibility tools essential in order to fulfill their daily needs. Traditionally, such assistive tools came in the form of expensive, specialized and at times heavy devices which visually impaired individuals had to independently look after and carry around. The past few years have witnessed an exponential growth in the computing capabilities and onboard sensing capabilities of mobile phones making them an ideal candidate for building powerful and diverse applications. We believe that the mobile phone can help concentrate the main functions of all the various specialized assistive devices into one, by enabling the rapid and cheap development of simple and ubiquitous assistive applications. The current thesis describes the design, implementation, evaluation and user-study based analysis of four different mobile applications, each one of which helps visually impaired people overcome an everyday accessibility barrier.

Our first system is a simple to operate mobile navigational guide that can help its visually impaired users repeat paths that were already walked once in any indoor environment. The system permits the user to construct a virtual topological map across points of interest within a building by recording the user's trajectory and walking speed using Wi-Fi and accelerometer readings. The user can subsequently use the map to navigate previously traveled routes without any sighted assistance. Our second system, Mobile Brailler, presents several prototype methods of text entry on a modern touch screen mobile phone that are based on the Braille alphabet and thus are convenient for visually impaired users. Our third system enables visually impaired users to leverage the camera of a mobile device to accurately recognize currency bills even if the images are partially or highly distorted. The final system enables visually impaired users to determine whether a pair of clothes, in this case of a tie and a shirt, can be worn together or not, based on the current social norms of color-matching.

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