How to interpret data imported from logfiles

I got the logfilfe analyze script working and was very astonished about the visitor count.
When I analyze the access logs with piwik's import function the number of visitors reported by piwik is about 10 to 20 times higher than the data recorded via the java script tracking code.
I use the import script without the parameters "enable-bots", "enable-http-errors" and "enable-redirects".

Do you have some tips if I am misunderstanding the data? Do I use the script the right way?

Thanks,
Jens