How to filter captchas from other images?

Question

CAPTCHA

How can I filter out captchas from such images

Here is the captcha:


Maybe compare pixels somehow?

Answer 1

Captcha can be any picture.
so "in the general case" - no way.
And if you know something about your captchas, then you can already use it,
for example - "all captchas are dirty yellow-green numbers on a white background" - that means we are looking for images where the colors are white and dirty yellow-green. If there are no others - then captcha, if there is then no captcha.
You can have any conditions, depending on what kind of captcha.

Answer 2

You can get telemetry (such as the verbose mode from imagemagick 's identify program ) from all pictures and try to filter out multi-color/square pictures. Also pictures, where almost nothing is drawn. You can try to try to recognize with tesseract.js .