The Generalized Beamformer in the UltraSound ToolBox

Software beamforming has enabled the introduction of a myriad adaptive beamformers. To reproduce and compare those techniques, a unified beamforming framework is imperative. Here, we propose such a framework, called the Generalized Beamformer (GB), which provides a unified approach to most state-of-the-art beamforming techniques through a single core expression. This generalization is achieved through a range of delay and apodization models that enable translation across various transmit sequences. Exploiting the GB we also demonstrate a novel synthetic transmit focusing strategy for adaptive beamforming, where signals are coherently combined across transmit events prior to e.g. Coherence Factor or Minimum Variance processing. For the investigated Coherent Plane-Wave Compounding (CPWC) case, this substantially reduces computational complexity while improving resolution and maintaining contrast. The GB is implemented within the open-source UltraSound ToolBox (USTB) for MATLAB, and its pixel-based approach provides flexibility in scan grid definition. The framework is shown to successfully beamform conventional transmit sequences, including focused, diverging, plane, and single-element transmissions. Its versatility is showcased through diverse applications, including in vivo cardiac and fetal imaging, as well as subsea sonar.