ADAPTIVE TEMPORAL DECIMATION ALGORITHM WITH DYNAMIC TIME WINDOW

Decimation approaches for image processing have been widely used for v arious applications. For video processing, decimation refers to sampli ng the frame rate in order to reduce the number of processing frames. Most of these temporal decimation methods discard whole frames; as a r esult, some high-speed motions could be completely eliminated while so me redundant frames might remain in the processing frames. Until, rece ntly, an adaptive temporal decimation approach has been successfully d eveloped by Olstad to take both spatial and temporal information into consideration and is fully compatible with some existing discrete cosi ne transform (DCT)-based standards, such as MPEG and H.261. Moreover, it theoretically preserves all high activity motions and discards all low activity motions. However, we found that it is still not fully ada ptive due to the confinement of the size of the time window. The disco ntinuity detection method is quite complex and, more importantly, the efficiency of coding block position maps is fairly low. In this paper, we propose to resolve the problem of the time window by a dynamic tim e window approach. By using variable sizes of the time window, the opt imal number of remaining frames could be produced. It also enhances th e visual quality of the resulting video while the compression is compa rable with the conventional approach. Based on our proposed algorithm, a simple but efficient quantization process has been used to replace the highly complex temporal discontinuity detection. The conventional adaptive temporal decimation algorithm operates on the basis of block sequences, but our dynamic approach which can retain all high activity blocks operates on the spatiotemporal domain. This approach can reduc e redundant planes with slow activity and give higher precision for bl ocks with high activity. Experimental results show that the proposed a lgorithm achieves the optimal number of remaining frames.