Synthetic aperture (SA) imaging can provide a uniform lateral resolution but an insufficient signal-to-noise ratio (SNR). SA method with bidirectional pixel-based focusing (SA-BiPBF) has the ability to obtain a higher quality image than conventional SA imaging. In this paper, an enhanced SA-BiPBF named full aperture received far-focused pixel-based (FrFPB) is firstly proposed to obtain a high resolution image. An adjustable zero-cross factor scaled Wiener postfilter (AZFsW) is then implemented in FrFPB for improving contrast ratio (CR). The adjustable zero-cross factor is calculated using the polarity of echo signals sequence with an adjustable coefficient $\sigma$ to estimate the signal coherence, and it is combined with Wiener postfilter to obtain a good capability of noise reduction and background speckle pattern preservation. Simulation and experiments have been conducted to evaluate the imaging performance of the proposed methods. Results show that FrFPB can obviously improve the resolution in comparison with SA-BiPBF, and contrast-to-noise ratio (CNR) and speckle signal-to-noise ratio (sSNR) are retained. In addition, AZFsW can achieve a much higher CR than SA-BiPBF. When $\sigma$ is 0.6, the CR improvement is 96.7% in simulation, 78.7% in phantom experiment, and 49.2% in $in$-$vivo$ experiment. To evaluate the imaging performance of AZFsW, coherence factor, conventional Wiener postfilter, and scaled Wiener postfilter are implemented. The imaging results show that when $\sigma$ is in the range of [0.6, 0.7], AZFsW exhibits a satisfying comprehensive imaging performance.

合成孔径（SA）成像可提供均匀的横向分辨率，但信噪比（SNR）不足。具有双向基于像素的聚焦（SA-BiPBF）的SA方法具有比常规SA成像获得更高质量图像的能力。在本文中，首先提出了一种增强的SA-BiPBF，称为全光圈接收基于远聚焦像素（FrFPB），以获得高分辨率的图像。然后在FrFPB中实现了可调节的零交叉因子缩放的维纳后置滤波器（AZFsW），以提高对比度（CR）。使用具有可调系数的回波信号序列的极性来计算可调过零因子$\sigma$估计信号相干性，并将其与维纳后置滤波器结合使用，可以获得良好的降噪和背景散斑图保留能力。仿真和实验已经进行，以评估所提出的方法的成像性能。结果表明，与SA-BiPBF相比，FrFPB可以显着提高分辨率，并且保留了对比度噪声比（CNR）和斑点信号噪声比（sSNR）。另外，AZFsW可以实现比SA-BiPBF高得多的CR。什么时候$\sigma$ 为0.6，模拟中的CR改善为96.7％，幻像实验中的CR改善为78.7％，而模拟中的CR改善为49.2％ $\mathrm{一世}ñ$--$v\mathrm{一世}vØ$实验。为了评估AZFsW的成像性能，采用了相干因子，常规的维纳后置滤波器和定标的维纳后置滤波器。成像结果表明$\sigma$ 在[0.6，0.7]的范围内，AZFsW表现出令人满意的综合成像性能。