School of Mathematics and Information Engineering, Chongqing University of Education, Chongqing 400065, China.
Stork Healthcare Ltd., Chengdu 610041, China.
Comput Math Methods Med. 2020 Aug 28;2020:1503791. doi: 10.1155/2020/1503791. eCollection 2020.
A novel adaptive beamformer named filtered-delay multiply and sum (F-DMAS) has recently been proposed. Compared to the delay and sum (DAS) beamforming algorithm, F-DMAS can efficiently improve the resolution and contrast. However, the DAS can still be seen in the expansion of DMAS. Therefore, we rearrange the pair-wised signals in terms of lag in DMAS and then synthesize a lot of new signals. Thanks to the relationship between the spatial coherence and lag, these new signals can be thought of as sorted by the spatial coherence. Thus, we apply two phase-related factors, the polarity-based factor (PF) and the sign coherence factor (SCF), which are evaluated based on new signals, to weight the output of DMAS. The two approaches are consequently referred to as LAG-DMAS-PF and LAG-DMAS-SCF, respectively. The results show that, compared to F-DMAS and DAS, our proposed methods can improve the resolution and contrast to some extent without increasing too much computational complexity. In the comparison between LAG-DMAS-PF and LAG-DMAS-SCF, the latter has better performance, but the former can better protect image details.
最近提出了一种名为滤波延迟乘法和求和（F-DMAS）的新型自适应波束形成器。与延迟求和（DAS）波束形成算法相比，F-DMAS 可以有效地提高分辨率和对比度。然而，在 DMAS 的扩展中仍然可以看到 DAS。因此，我们根据 DMAS 中的滞后重新排列成对信号，然后合成许多新信号。由于空间相干性和滞后之间的关系，这些新信号可以被视为按空间相干性排序。因此，我们应用两个与相位相关的因素，基于极性的因素（PF）和符号相干性因素（SCF），基于新信号进行评估，以加权 DMAS 的输出。这两种方法分别称为 LAG-DMAS-PF 和 LAG-DMAS-SCF。结果表明，与 F-DMAS 和 DAS 相比，我们提出的方法可以在不增加太多计算复杂度的情况下在一定程度上提高分辨率和对比度。在 LAG-DMAS-PF 和 LAG-DMAS-SCF 之间的比较中，后者性能更好，但前者可以更好地保护图像细节。
