Abstract
Deaf people around the globe use sign languages for their communication needs. Innovations of new technologies, such as smartphones, offer a host of new functionalities to their users. If such mobile devices become capable of recognizing sign languages, this will open up the opportunity for offering significantly more user-friendly mobile apps to sign language users. However, in order to achieve satisfactory results, there are many challenges that must be considered and overcome, such as light conditions, background noise, processing, and energy limitations. This paper aims to cover the most recent techniques in mobile-based sign language recognition systems. We categorize existing solutions into sensors-based and vision-based, as these two categories offer distinct advantages and disadvantages. The primary focus of this literature review is on two main aspects of sign language recognition: feature detection and sign classification algorithms.