Adobe Acrobat Reader 7.0
Total Files---> 8
Total Size---> 32.7 MB
Portable Zip---> 30.2 MB
Enhanced Deflate---> 30.2 MB
Bzip 2---> 30.3 MB
PPMD---> 30.7 MB
LZX---> 30.1 MB
FEAD---> 19.8 MB
Panda Antivirus Titanium 2006
Total Files---> 321
Total Size---> 80.4 MB
Portable Zip---> 39.4 MB
Enhanced Deflate---> 38.9 MB
Bzip 2---> 38.0 MB
PPMD---> 35.0 MB
LZX---> 32.0 MB
FEAD---> 22.2 MB
As you can see, the FEAD technology is much more effective in compressing pre-compressed files. It is even better than the best these days (PPMD and LZX) by some 30% (Approx). UPX is the only algorithm I have heard about that can compress Portable Executables by that much. Then I learned that it was indeed a modified version of the UPX algorithm which they have named NOS. Some people reckon, that in doing so they have violated the GPL. Check this out for more details.
Possible technique: Netopsystems have come out with a basic but effective technique to copy repeated files just once in the source package and copy them as many times required during recomposition in the destination folder(s). There must be many other things they have put into use, because UPX can only compress PEs which in the case of Panda Antivirus is 10.5 MB in size. Had they compressed the 10.5 MB PEs to 0 Byte, that would have accounted for the 10 MBs deficit (which even by Napolean's standard is impossible) . So, they must be using some other algorithm for other files.
Another probability: They haven't released their FEAD Optimizer for users, rather they rely on customers handing their Setup files to them for analysis and compression. It might be this step that hands them the edge. Maybe they search the files for every drop of fatty byte they can shed.
Whatever be it, the company has opened doors for further research in the field of compression algorithms, which was seeming to have reached its zenith.


