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Video Compression and MPEG
Published in John Watkinson, The Art of Digital Video, 2013
In real television program material objects move around before a fixed camera or the camera itself moves. Motion compensation is a process that effectively measures motion of objects from one picture to the next so that it can allow for that motion when looking for redundancy between pictures. Figure 6.9 shows that moving pictures can be expressed in a three-dimensional space, which results from the screen area moving along the time axis. In the case of still objects, the only motion is along the time axis. However, when an object moves, it does so along the optic flow axis, which is not parallel to the time axis. The optic flow axis joins the same point on a moving object as it takes on various screen positions.
Compression
Published in John Watkinson, Convergence in Broadcast and Communications Media, 2001
In real television program material objects move around before a fixed camera or the camera itself moves. Motion compensation is a process which effectively measures motion of objects from one picture to the next so that it can allow for that motion when looking for redundancy between pictures. Chapter 7 showed that moving pictures can be expressed in a three-dimensional space which results from the screen area moving along the time axis. In the case of still objects, the only motion is along the time axis. However, when an object moves, it does so along the optic flow axis which is not parallel to the time axis. The optic flow axis joins the same point on a moving object as it takes on various screen positions.
Image processing
Published in Geoff Lewis, Communications Technology Handbook, 2013
A technique commonly applied to the digital representation of images that have been subjected to compression or bit rate reduction. Motion compensation provides a means of improving the performance of any temporal compression, particularly in images where motion is continually taking place (video). In order to apply such compensation, it is first necessary to determine what part of the image is moving and where it is moving to.
Anti-HEVC Recompression Video Watermarking Algorithm Based on the All Phase Biorthogonal Transform and SVD
Published in IETE Technical Review, 2018
Chengyou Wang, Rongyang Shan, Xiao Zhou
By researching current video watermarking systems, the watermark embedding locations of compression domain video watermarking concentrate on four locations in the video compression process. Figure 2 is a schematic diagram of the video watermark embedding positions. MC means motion compensation and ME is the motion estimation. Cell 1 indicates that watermark information is embedded in DCT transform coefficients. Cell 2 indicates that the watermark information is embedded in the quantized transform coefficients, and the positions indicated by cells 3 and 4 denote that the watermark information is embedded by modifying the MV and variable length coding stream, respectively. Currently, most of the digital watermarking algorithms based on the frequency domain will select position 1 and position 2 as the embedding positions. Additionally, the video watermarking algorithm in the compression domain, if a reversible digital watermark is adopted, can completely remove the watermark information on the decoding side, which does not affect the video quality and can adjust the watermark based on human eyes. However, in the time domain-based watermarking scheme, the watermark information may be lost after compression, which may affect the video quality.
Real-time visual transmission mechanism of graphics diversity based on mobile 3D graphics matching algorithm
Published in International Journal of Computers and Applications, 2021
Block-type motion estimation code is adopted for all traditional visual communication coding standard for the diversity of advertising graphs, and it is a motion compensation prediction among frames to reduce time redundancy. The block of the current frame is used to search optimal prediction block (optimal matching block) in the search scope of reference frame for traditional motion estimation operation, and the motion vector indicates the position of the optimal matching block with zero motion block. Rate-distortion optimization (RDO) function is a comprehensive evaluation method to realize the optimal mode of data flow between performance and motion estimation: