Understanding face and eye visibility in front-facing cameras of smartphones used in the wild

Commodity mobile devices are now equipped with high-resolution front-facing cameras, allowing applications in biometrics (e.g., FaceID in the iPhone X), facial expression analysis, or gaze interaction. However, it is unknown how often users hold devices in a way that allows capturing their face or eyes, and how this impacts detection accuracy. We collected 25,726 in-the-wild photos, taken from the front-facing camera of smartphones as well as associated application usage logs. We found that the full face is visible about 29% of the time, and that in most cases the face is only partially visible. Furthermore, we identified an influence of users' current activity; for example, when watching videos, the eyes but not the entire face are visible 75% of the time in our dataset. We found that a state-of-the-art face detection algorithm performs poorly against photos taken from front-facing cameras. We discuss how these findings impact mobile applications that leverage face and eye detection, and derive practical implications to address state-of-the art's limitations

M-health review: joining up healthcare in a wireless world

In recent years, there has been a huge increase in the use of information and communication technologies (ICT) to deliver health and social care. This trend is bound to continue as providers (whether public or private) strive to deliver better care to more people under conditions of severe budgetary constraint

A longitudinal review of Mobile HCI research Methods

This paper revisits a research methods survey from 2003 and contrasts it with a survey from 2010. The motivation is to gain insight about how mobile HCI research has evolved over the last decade in terms of approaches and focus. The paper classifies 144 publications from 2009 published in 10 prominent outlets by their research methods and purpose. Comparing this to the survey for 2000-02 show that mobile HCI research has changed methodologically. From being almost exclusively driven by engineering and applied research, current mobile HCI is primarily empirically driven, involves a high number of field studies, and focus on evaluating and understanding, as well as engineering. It has also become increasingly multi-methodological, combining and diversifying methods from different disciplines. At the same time, new opportunities and challenges have emerged

An ecologically valid evaluation of an observation-resilient graphical authentication mechanism

Alphanumeric authentication, by means of a secret, is not only a powerful mechanism, in theory, but prevails over all its competitors in reality. Passwords, as they are more commonly known, have the potential to act as a fairly strong gateway. In practice, though, password usage is problematic. They are (1) easily shared, (2) trivial to observe and (3) maddeningly elusive when forgotten. Moreover, modern consumer devices only exacerbate the problems of passwords as users enter them in shared spaces, in plain view, on television screens, on smartphones and on tablets. Asterisks may obfuscate alphanumeric characters on entry but popular systems, e.g. Apple iPhone and Nintendo Wii, require the use of an on-screen keyboard for character input. A number of alternatives to passwords have been proposed but none, as yet, have been adopted widely. There seems to be a reluctance to switch from tried and tested passwords to novel alternatives, even if the most glaring flaws of passwords can be mitigated. One argument is that there has not been sufficient investigation into the feasibility of the password alternatives and thus no convincing evidence that they can indeed act as a viable alternative. Graphical authentication mechanisms, solutions that rely on images rather than characters, are a case in point. Pictures are more memorable than the words that name them, meaning that graphical authentication mitigates one of the major problems with passwords. This dissertation sets out to investigate the feasibility of one particular observation-resilient graphical authentication mechanism called Tetrad. The authentication mechanism attempted to address two of the core problems with passwords: improved memorability and resistance to observability (with on-screen entry). Tetrad was tested in a controlled lab study, that delivered promising results and was well received by the evaluators. It was then deployed in a realistic context and its viability tested in three separate field tests. The unfortunate conclusion was that Tetrad, while novel and viable in a lab setting, failed to deliver a usable and acceptable experience to the end users. This thorough testing of an alternative authentication mechanism is unusual in this research field and the outcome is disappointing. Nevertheless, it acts to inform inventors of other authentication mechanisms of the problems that can manifest when a seemingly viable authentication mechanism is tested in the wild