[viseztrance]

I don't know how it can be fully prevented other than disabling javascript, but in my opinion firefox with "privacy.resistFingerprinting" is a good start, though you'll still stand out because few people are using it.

I've seen a script that performed two canvas fingerprints - a complex, and a simpler one. The latter being so simple always returned the same value regardless of the browser, so it was there to see if you have altered the canvas value. That's why changing your fingerprint might still leave you trackable.