Shadow detection is an important pre-processing step often used in scene interpretation or shadow removal applications. In this paper, we propose a single-image shadow detection method. Many other methods use multiple images; we use a quaternion representation of colour images to extract shadows from only one input image. The generation of the final binary shadow mask is done via automatic threshold selection. Evaluation is carried out qualitatively and quantitatively over three challenging datasets of indoor and outdoor natural images. The results of qualitative assessment were consistent with the statistical results, where the proposed method improves the performance of shadow detection when compared with state-of-the-art methods.

With the wide spread of devices that support mobile computing environment and applications, there is a need to develop new services that satisfy the needs of a mobile user. In this paper, we propose a new approach of selecting routes in a public transport networks using a combined criteria to provide a service that finds geographical routes from a source to a destination based on user public transportation and service preferences. Based on the proposed criteria we allow a path selection to depend on two main preferences. The first preference is the public transport media which could include bus, train, metro, and walking etc. The second preference is a service related one and includes the best network connection availability, such as GPRS, 3G, and 4G etc, along the available paths. We think that a combination of these two preferences is of high importance in our current daily life since a continuous availability of internet connection is crucial even while we are on the move using any public transport media. The proposed approach have been modelled and simulated via a C++ program. The simulation has been used to evaluate the proposed combined criteria in comparison with other approaches which are based just on the first preference, namely the public transport media, and with the simple shortest route selection approach. Results show that our combined criteria allow a mobile user to select geographical routes according to the preferred public transport media while being able to stay connected with higher transmission rate network connections.