Among clinical photoacoustic and ultrasound beamforming (BF) techniques, a nonlinear p-th root delay and sum (NL-p-DAS) exhibits better contrast and resolution than conventional delay-and-sum. However, despite its advantages, signal loss and grainy speckles often degrade image quality by signal deformation. Thus, we proposed a new nonlinear BF algorithm called nonlinear p-th root spectral magnitude scaling (NL-p-SMS), which scales the signal in the spectral domain instead of the temporal domain. As a result, we achieved the enhanced contrast, contrast noise ratio, spatial resolution, and less grainy texture without significant signal or feature loss in both in vivo photoacoustic and ultrasound images.
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