sbpsplit reads the multi-level subband pyramid subband_pyramid (SBP format with L >= 1 in the header). Each band contained in subband_pyramid is then output to a series of output ICP-format files. The low-resolution baseband image is output first; the subsequent high-resolution subbands are output in order horizontal, vertical, and diagonal, starting at level L of the pyramid (low resolution, low frequency) and ending with level 1 (high resolution, high frequency).