The author is from the UCLA Brain Mapping Division, UCLA School of Medicine

Abstract Image time series for functional studies frequently vary relatively little from one time point to the next. We describe here a method of compression that calculates the change in signal intensity as a char (one-byte) as opposed to a short or long integer (usually two or four bytes), thus resulting in a compressed file size just over half the size of the original. The calculations and format are exceedingly simple; the compression time is comparable to the time required for a file copy, and is thus transparent to most users. The approach works equally well on any integer-based scanning modality, such as PET, CT or DSA. Our purpose in this communication is to advocate it as a standard, to promote free interchange of scan data.