Markus Mehnert

GPU-Based Background Illumination Correction for Blue Screen Matting

Separation of foreground objects from an almost constant backing color for video applications is still a common problem ([1]). For non-realtime situations there is a wide variety of different powerful mathematical approaches that can deal with most of the matting problems. For SD/HD studio realtime keyers most solutions are not applicable due to their algorithm complexity or high effort in user interaction. Excellent hardware keyers, such as Ultimattetrade work on most occasions, but even under controlled lighting in a blue-/greenscreen matting problems may occur, or creativity is limited by necessary lighting conditions. As a preprocessing algorithm for traditional chroma keying systems, we present a simple background illumination correction based approach for avoiding matting problems due to uneven or poor lit blue-/greenscreens. Using the computational power of GPU computing (GPGPU [2]) the presented algorithm is realtime capable and offers an improvement for achievable mattes quality.

Active DVB-T antenna: Evaluation of noise figure and gain with far field measurements

It is well known that both gain and noise figure depend on the source impedance. Minimum noise figure and maximum gain are two goals that cannot be reached simultaneously. In our particular case the problem consists of the fact that the source is a radiating element, e.g. a bow-tie radiator. All influences in the near field of this element cause a change to the source impedance. Thus, we have to avoid such influences during measurements and this was accomplished by our application of a far field method as described below.

Advanced receiver module for satellite standard ETSI-SDR (ESDR)

In this paper we give a short overview of the ESDR standard and its properties. A new general and modular receiving platform will be presented that can be adapted to different standards. The design methodology and implementation issues will be discussed. The advanced receiver module is very flexible and reduces implementation time of prototype receivers.

Interactive DMB System - Field Trial

Digital multimedia broadcasting (DMB) is a service that is based on digital audio broadcasting (DAB). The Institute for Media Technology operated a DAB test transmitter for evaluating simple DMB applications in the last two years. Now we start a field trial at the campus of our university aiming at interactive applications. The feedback channels will be the university intern local area network (LAN) and wireless local area network (WLAN). In this paper we present the technical requirements needed for operating the whole system. One part will be a prototype USB (universal serial bus) receiver that provides the data stream to the connected personal computer. Furthermore tested applications and new applications will be discussed.