There’s usually a couple of pictures that the captcha knows what it is, and some that it’s uncertain about. So you have both verification ones to check you’re actually doing it right and some used for training.
It was a lot more obvious with the book/text recaptcha where one word was a sully stylised one, and the other was scan from a book. You could usually put in whatever you wanted on the book text.
There’s usually a couple of pictures that the captcha knows what it is, and some that it’s uncertain about. So you have both verification ones to check you’re actually doing it right and some used for training.
It was a lot more obvious with the book/text recaptcha where one word was a sully stylised one, and the other was scan from a book. You could usually put in whatever you wanted on the book text.
I agree with the point it can be used for training on images, or text scanned from the book.
I doubt it is useful on generated image of text, and I can only recall those on text based captchas, can’t remember any scanned text.
Anyways, smart move from Google.