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Depending on the content of a video sequence and the settings used for encoding it, the amount of bits spent for the transmission of motion vector information can be enormous and in some cases even take the largest fraction of the bit rate. This is not always necessary since often wide areas, i.e. background or large foreground regions, fit the same global motion. Additionally, a global motion model...
Sprite coding, as standardized in MPEG-4 Visual, can result in superior performance compared to common hybrid video codecs both objectively and subjectively. However, state-of-the-art video coding standard H.264/AVC clearly outperforms MPEG-4 Visual sprite coding in broad bit rate ranges. Based on the sprite coding idea, this paper proposes a video coding technique that merges the advantages of H...
Several algorithms for global motion estimation in video sequences using pixel- or block-based approaches have been published. Most known pixel-based methods lack in performance while when using block-based algorithms working on motion vectors, robustness to outliers and accuracy is missing. In this paper we present the fundamentals of a significantly improved, robust block-based method for global...
Global motion is estimated either in the pixel domain or in block based domain. Until now, all the approaches regarding the latter are based on fixed sized blocks while the recent compression methods tend to use variable block sizes during motion estimation. In this paper we present a new procedure for global motion estimation based on a variable block size motion vector field. A block matching algorithm...
Pixel-based and motion vector-based global motion estimation (GME) techniques are evaluated in this paper with an automatic system for camera motion characterization. First, the GME techniques are compared with a frame-by-frame PNSR measurement using five video sequences. The best motion vector-based GME method is then evaluated together with a common and a simplified pixel-based GME technique for...
It is well known that video material with a static background allows easier segmentation than that with a moving background. One approach to segmentation of sequences with a moving background is to use preprocessing to create a static background, after which conventional background subtraction techniques can be used for segmenting foreground objects. It has been recently shown that global motion estimation...
The composition of panoramic images has recently received considerable attention. While panoramic images were first used mainly as a flexible visualization technique, they also found application in video coding, video enhancement, format conversion, and content analysis. The topic has enlarged and diverged into many specialized research directions, which makes it difficult to stay in touch with recent...
Object-based video coding, as standardized in MPEG-4 Part 2, can result in superior performance in comparison to common hybrid motion-compensated DCT-based approaches. We consider sprite coding which increases significantly the objective as well as the subjective quality of the coded video. The main challenge of this approach is the pre-segmentation of the video and the video content itself. To apply...
We consider the warping problem which appears in well-known image registration algorithms that use higher-order motion models. An implementation inspired by recent work and a new image registration algorithm are used for the analysis. Both approaches rely on frame-to-frame estimation. The key technique is the well-established gradient descent approach for the estimation of higher-order motion parameters...
In this study, an algorithm is proposed to solve the multi-frame structure from motion (MFSfM) problem for monocular video sequences in dynamic scenes. The algorithm uses the epipolar criterion to segment the features belonging to the independently moving objects. Once the features are segmented, the corresponding objects are reconstructed individually by using a sequential algorithm, which is also...
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