Compression and decompression of data such as a sequential list of executable instructions by uniformly applying a predictive model generated from one segment of the executable list as a common predictive starting point for the other segments of the executable list. A reduced scattering coefficient and an absorption coefficient are determined for the tissue, with the result that an effective path length can be determined. In determining the real-time information, it may be desired to provide the information quickly and use a smaller set of features that are available more quickly.