A sequence of n coefficients is compressed by determining a cost-determined sequence of n coefficient indices represented by a cost-determined sequence of (run, index derivative) pairs under a given quantization table and run-index derivative coding distribution, wherein each sequence of (run, index derivative) pairs defines a corresponding sequence of coefficient indices such that (i) each index in the corresponding sequence of coefficient indices is a digital number, (ii) the corresponding sequence of coefficient indices includes a plurality of values including a special value, and (iii) each (run, index derivative) pair defines a run value representing a number of consecutive indices of the special value, and an index-based value derived from a value of the index following the number of consecutive indices of the special value.