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Nowadays there are a vast number of devices and technologies available for the common citizen to improve their communication with others. This fosters the design and implementation of systems that explore the available features of these devices. In this paper, we propose a Bluetooth-based interactive system for delivering personalized information in high education institutions. The system allows informing, on a personalized way, the actors of an education institution on a free way using popular communication standards. The scenario we promote in the paper is mainly focused on learning environments, however the framework is also applicable in other shared public and semi-public spaces such as offices, homes, companies and many others. One of the most important contributions of this work is to combine public displays and personal mobile devices for delivering personalized information according to the students’ location. A prototype has been built and discussed with demonstrative user scenarios. Early results show that teachers and students found some advantages in this system comparing to traditional approaches. This system can effectively support a wide range of activities for students. It provides to each student the possibility to have a personal interaction with the technology in an authentic and appropriate use context. Features like the system’s architecture, prototype and system’s evaluation are explained in the paper. Results show that this system can be an important complement to other popular systems in education environment (e.g. e-mail, chats, Wikis, forums, e-learning platforms etc.).

This paper addresses the most relevant aspects of lossy image coding techniques, and presents an evaluation study on this subject, using several transforms and different methods in the transform domain. We developed different transform based image coders/decoders (codecs) using different transforms, such as the discrete cosine transform, the discrete wavelet transform and the S transform. Besides JPEG Baseline, we also use other techniques and methods in the transform domain such as a DWT based JPEG-like (JPEG DWT), a JPEG DWT with visual threshold (JPEG-VT), a JPEG–like coder based on the ST, and an EZW coder. The codecs were programmed in MATLAB™, using custom and built-in functions. The structures of the codecs are presented, also as some experimental results which allow us evaluate them, and support this study.

This paper presents a comparative study on image coders using the discrete cosine transform and the discrete wavelet transform, addressing in particular the JPEG-like and the EZW based image coders. We compare and evaluate the JPEG Baseline Image coder (using the DCT), a JPEG-like image coder based on the DWT, and an EZW coder, which is also based on the DWT. Taking into account the differences on the architecture of the coders, we compare them by using the same test images, for approximately the same conditions and characteristics, namely the approximately equal compression ratio.