Table t:sum summarizes the compression algorithms that don't split the data into planes. We conservatively calculated the compression ratio relative to the binary file size, not to the original ASCII file. Table t:sumsplit shows the results when the elevations were first split into hi and lo order bytes, and the two files compressed separately. Showing the compression ratios for the separate bytes didn't seem meaningful.
Table 4: Comparison of Compression Methods on the Adir512 Split
into Hi and Lo Bytes
Finally, in these tests, we used Sun Sparc IPC and 10/30 Unix workstations, and programmed in C++ with the Apogee compiler. Tomas Rokicki's dvips, Jef Poskanzer's Portable Bit Map (PBM) package, Netpbm version, and John Bradley's xv were also very useful.