ikercito some watermarks that stay in the image structure can be wiped out: just adjust and convert the picture in a paint software and hop, gone ! some other way is a subtle watermark, that does not ruin the image (hard) AND also does not seem to be a watermark and just a genuine part of the picture (a tatoo, a symbol etc, not on front layer and such) and that no video adjustmeent (minor postwork) or compression will wipe out :)