Koc U V, Liu K R
Lucent Technologies, Bell Laboratories, Murray Hill, NJ07974, USA.
IEEE Trans Image Process. 1998;7(7):948-65. doi: 10.1109/83.701146.
We propose novel discrete cosine transform (DCT) pseudophase techniques to estimate shift/delay between two one-dimensional(1-D) signals directly from their DCT coefficients by computing the pseudophase shift hidden in DCT and then employing the sinusoidal orthogonal principles, applicable to signal delay estimation remote sensing. Under the two-dimensional (2-D) translational motion model, we further extend the pseudophase techniques to the DCT-based motion estimation (DXT-ME) algorithm for 2-D signals/images. The DXT-ME algorithm has certain advantages over the commonly used full search block-matching approach (BKM-ME) for application to video coding despite certain limitations. In addition to its robustness in a noisy environment and low computational complexity, O(M(2)) for an MxM search range in comparison to the O(N(2) . M(2)) complexity of BKM-ME for an NxN block, its ability to estimate motion completely in DCT domain makes possible the fully DCT-based motion-compensated video coder structure, which has only one major component in the feedback loop instead of three as in the conventional hybrid video coder design, and thus results in a higher system throughput. Furthermore, combination of the DCT and motion estimation units can provide space for further optimization of the overall coder. In addition, the DXT-ME algorithm has solely highly parallel local operations and this property makes feasible parallel implementation suitable for very large scale integration (VLSI) design. Simulation on a number of video sequences is presented with comparison to BKM-ME and other fast block search algorithms for video coding applications even though DXT-ME is completely different from any block search algorithms.
我们提出了新颖的离散余弦变换（DCT）伪相位技术，通过计算隐藏在DCT中的伪相移，然后运用正弦正交原理，直接从两个一维（1-D）信号的DCT系数中估计它们之间的偏移/延迟，该技术适用于遥感信号延迟估计。在二维（2-D）平移运动模型下，我们进一步将伪相位技术扩展到用于二维信号/图像的基于DCT的运动估计（DXT-ME）算法。尽管存在一定局限性，但DXT-ME算法在应用于视频编码时，相较于常用的全搜索块匹配方法（BKM-ME）具有一定优势。除了在噪声环境中的鲁棒性和低计算复杂度（对于MxM搜索范围为O(M²)，而BKM-ME对于NxN块的复杂度为O(N².M²)）外，其在DCT域中完全估计运动的能力使得基于完全DCT的运动补偿视频编码器结构成为可能，该结构在反馈回路中只有一个主要组件，而不是传统混合视频编码器设计中的三个，从而提高了系统吞吐量。此外，DCT和运动估计单元的结合为整个编码器的进一步优化提供了空间。此外，DXT-ME算法仅具有高度并行的局部操作，这一特性使得适合超大规模集成（VLSI）设计的并行实现成为可能。本文给出了对多个视频序列的仿真结果，并与BKM-ME和其他用于视频编码应用的快速块搜索算法进行了比较，尽管DXT-ME与任何块搜索算法完全不同。
