Up-sampling oriented frame rate reduction

Reducing the frame rate of a sequence results in the information loss of interpolated frames that cannot be recovered by temporal up-sampling. The most prevalent frame rate reduction method is the direct down-sampling, which maintains the original frames of the input sequence with a constant interval. It achieves wide applications due to simplicity. However, it neglects the influences on interpolated frames brought by temporal up-sampling. To maintain more information during down-sampling, which will be used for interpolation, this paper proposes an up-sampling oriented frame rate reduction by hinging the temporal up-sampling and down-sampling. It is designed with the goal of improving the quality of up-sampled frames while keeping the down-sampled sequence faithful to the input one. For a particular temporal up-sampling method, e.g., motion compensation frame interpolation, the optimal down-sampled frame is the one that not only minimizes the difference between the original and the down-sampled frames but also minimizes the difference between the original and the corresponding up-sampled frames. Users can make a tradeoff between the two difference terms by selecting a proper lagrange factor depending on the applications. Furthermore, to decrease the space and computational complexity, a block-wise implementation is also devised in this paper. Experimental results conducted on various sequences demonstrate that the proposed frame rate reduction is able to significantly improve the quality of up-sampled frames compared with other down-sampling methods.

We propose a frame rate reduction oriented for upsampling.
► We propose a block‐wise implementation to decrease the space and computational complexity.
► We apply the proposed the method in low bitrate video coding.