Various image authentication that can be thought of as harassment difficult to decipher

In addition to ID and password, such as when registering to a net service or recovering a forgotten password, "image authentication (captcha)" that authenticates whether it is human or not by inputting the characters displayed on the screen Although it may be seen, there seems to be image authentication that makes it very difficult to decipher and wants to thrust into "I do not feel like logging in!"

Also in JapanImage authentication of GmailIt is said that it is difficult to read characters and difficult to read, but there seems to be something in the world that it is difficult to log in beyond Gmail.

Image is from below.
It is hard to understand what you are writing. Gmail is similar to this.


I do not know which characters to enter and which to enter.


Although it seems to enter the character where the picture of the cat is drawn, it is difficult to understand which cat is hidden by the character.


A difficult calculation formula. I will lose the feeling of logging in.


Calculation formula using differentiation.


What choices will be made when assembling the drawing on the right.


In another sense, "difficult to understand" that "Choose three cute kids".


I have no idea where the letters are written.
The Hardest Captcha. On Flickr - Photo Sharing!

By Britt Selvitelle

You can see other images from below.
Worst Captchas of All Time