Analysis of coding tools and improvement of text readability for screen content

Abstract—Current video coding standards perform well for video sequences captured by a real camera. The aperture of the camera’s optical system smooths the content and attenuates higher frequencies. New application scenarios, enabled by the growing number of high bit rate internet gateways, however, make it necessary to take a closer look at the efficiency of such standards in handling artificial content. Remote desktop appli-cations for example often include text parts. As a consequence, these content types contain sharp edges or high frequencies, which are considered less important in natural video and are therefore treated less carefully. The frequent result is an increased occurrence of artefacts or the loss of information that is actually important to the user. This paper gives an analysis of such artificially created video sequences, evaluates the performance of current coding tools for this type of content and proposes a simple, yet effective way to maintain readability of text within video material using only well considered encoder control and without the need of large additional modules. I

Low bit rate roi based video coding for hdtv aerial surveillance video sequences

For aerial surveillance systems two key features are important. First they have to provide as much resolution as possible, while they secondly should make the video available at a ground station as soon as possible. Recently so called Unmanned Aerial Vehicles (UAVs) got in the focus for surveillance operations with operation targets such as environmental and disaster area monitoring as well as military surveillance. Common transmission channels for UAVs are only available with small bandwidths of a few Mbit/s. In this paper we propose a video codec which is able to provide full HDTV (1920 × 1080 pel) resolution with a bit rate of about 1–3 Mbit/s including moving objects (instead of 8– 15 Mbit/s when using the standardized AVC codec). The coding system is based on an AVC video codec which is controlled by ROI detectors. Furthermore we make use of additional Global Motion Compensation (GMC). In a modular concept different Region of Interest (ROI) detectors can be added to adjust the coding system to special operation targets. This paper presents a coding system with two motion-based ROI detectors; one for new area detection (ROI-NA) and another for moving objects (ROI-MO). Our system preserves more details than an AVC coder at the same bit rate of 1.0 Mbit/s for the entire frame. 1

Prioritizing Content of Interest in Multimedia Data Compression

Image and video compression techniques make data transmission and storage in digital multimedia systems more efficient and feasible for the system's limited storage and bandwidth. Many generic image and video compression techniques such as JPEG and H.264/AVC have been standardized and are now widely adopted. Despite their great success, we observe that these standard compression techniques are not the best solution for data compression in special types of multimedia systems such as microscopy videos and low-power wireless broadcast systems. In these application-specific systems where the content of interest in the multimedia data is known and well-defined, we should re-think the design of a data compression pipeline. We hypothesize that by identifying and prioritizing multimedia data's content of interest, new compression methods can be invented that are far more effective than standard techniques. In this dissertation, a set of new data compression methods based on the idea of prioritizing the content of interest has been proposed for three different kinds of multimedia systems. I will show that the key to designing efficient compression techniques in these three cases is to prioritize the content of interest in the data. The definition of the content of interest of multimedia data depends on the application. First, I show that for microscopy videos, the content of interest is defined as the spatial regions in the video frame with pixels that don't only contain noise. Keeping data in those regions with high quality and throwing out other information yields to a novel microscopy video compression technique. Second, I show that for a Bluetooth low energy beacon based system, practical multimedia data storage and transmission is possible by prioritizing content of interest. I designed custom image compression techniques that preserve edges in a binary image, or foreground regions of a color image of indoor or outdoor objects. Last, I present a new indoor Bluetooth low energy beacon based augmented reality system that integrates a 3D moving object compression method that prioritizes the content of interest.Doctor of Philosoph