| 摘要 |
<p>A sequence of data samples X[n] is point symmetrically extended to provide an extended sequence of samples x[n]. The points of symmetry (25) can be at the ends (17, 19) of the sequence (as in Fig. 4 (a)), such that the samples at the ends are not duplicated but the points of symmetry are at the values of those samples. Thus, the extensions are formed by duplications (27) of a predetermined number of the other samples. Alternatively (as shown in Fig.4 (b)), the points of symmetry (25) can be a half-sampling rate beyond (23, 25) the samples at the ends of the sequence so that those samples are also duplicated (27) to provide the extensions. For tiled image data, image compression and reconstruction utilising the point symmetric technique provides a very good reconstructed image with reduced artifacts at the tile boundaries. For this, both locations of the points of symmetry mentioned above need to be utilised for different sequences depending on whether there are odd or even numbers of samples in the sequences and whether the filters used are odd or even in length.</p> |
