How to make captcha text difficult to recognize?

Question

Text recognising

There is a ton of information about pattern recognition and captchas. But in the end, what are the most difficult to solve recognition options for displaying text or images? How should an image be formed so that its recognition becomes the most non-trivial and difficult task?
So far, I know that you should not use standard fonts or fixed ones. What else can be done?

Answer 1

How should an image be formed so that its recognition becomes the most non-trivial and difficult task?

If you have users from Russia, write on the captcha a construction in the spirit
of a thousand
thousand and a hundred and
twenty
seven
in italics, imitating handwritten text with a combination of letters, and adding a slight distortion like waves.
Display the image via JS, and in case of a real disaster, add its display on click. And before clicking and without JS enabled, show the "left" captcha, through the input of which you catch bots.