“…Recently, methods combined with adaptive beamforming methods have been proposed [11][12][13] that can improve the quality of whole images, but the implementation of these methods is still challenging due to their high computational complexity [13,14]. In the nearest-neighbor cross-correlation (NNCC) method [6,12,13], the number of multiplications is expressed approximately as N mult = (N − 1) × K image × L image × M, where N, L image and K image are the number of channels, scanlines and samples per a scanline in the whole image, respectively, and M is the total number of samples that contribute to the cross-correlation function. For an abdominal image with depth of 160 mm, the number of multiplications is approximately 1.3 billion × M when N =128, L image = 256 and K image = 4k; thus, the implementation of these methods in real time would be challenging.…”