Visual Confirmation Systems (like
maxk said are used for protection against automated registrations to ensure bigger security of a particular service.
To read out such a text you could use either weighted pattern matching (check if the gifen image part matches a known pattern and how likely that match would be) or the way FineReady does by
OCR, where OCR would be the better, but more complicated way. To use OCR you need a well trained
"NEURONAL NETWORK" that is trained to character detection.
All in all that issue is quite complicated and there exists no generalized solution (I even know some VCS that are even hardly manageable by humans).
Anyone who is capable of being elected president should on no account be allowed to do the job.
Ich code EdgeMonkey - In dubio pro Setting.