by using ocr system? or somethings?
This is a very interesting captcha. Do you have a link to it? Or can you tell me if it is always the same 3 symbols? (If not, can you post a few more screenshots of different symbols?)
Every time different three symbols. And different colors and size on up and down. Only shapes are same.
here are some screenshorts
You probably won’t be able to use ui vision for this type of captcha as the images always rotate and therefore it is impossible to compare them