zEscola Superior de Tecnologia e Gest~ao Summary
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Abstract:
This paper describes how the combination of geometric transformations in both the spatial and pixel domains can be used for video coding. The geometric transformation applied in the spatial domain is able to track movements such that, for low bit rate video coding, the motion vectors alone can be used to represent a complex motion of moving objects. The introduction of such a transformation in the pixel domain allows the recovering from nonuniform intensity changes, as well as uncovered background. The presented method achieves a compression efficiency far superior than that obtained by using conventional block matching motion compensation. In order to reduce the computational complexity, image segmentation, fast transformation and interpolation algorithms are used. During the past decade a significant progress in the field of video coding has been made, and various intra-frame coding techniques have been devised. However, most of the efficiency of low bit rate video coding is due to the motion compensation. In this sense, half-a-pixel accuracy block-matching motion estimation has been used in MPEG [1], in order to improve the coding efficiency of this codec over H.261 [2]. In the mean time H.263 [3], a successor to H.261 for lower bit rate applications, uses also half-a-pixel accuracy. It is important to
Citations
| 52 | Generic Coding of Moving Pictures and Associated Audio”, Committee draft – ISOIEC - 1993 |
| 14 | Recommendation H.261, Video codec for audiovisual services at p x 64 kbit/s – ITU-T - 1993 |
| 13 | Motion compensation for very low bit-rate video – Ghanbari, Faria, et al. - 1995 |
| 4 | Recommendation H.263, video coding for low bitrate communication – ITU-TSG15 - 1995 |
| 1 | Low bit rate video coding with spatio-temporal geometric transforms – Faria, Ghanbari - 1996 |
