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image verification

Mirko Froehlich
Ranch Hand

Joined: Aug 21, 2000
Posts: 114
Does anybody know an open source Java implementation of an image verification form? I'm not really sure how this feature is officially called, but I am talking about those automatically generated images that contain scrambled text which users need to enter on various websites these days in order to verify that they are indeed human and not a spam bot.

Any pointers would be appreciated.

David O'Meara

Joined: Mar 06, 2001
Posts: 13459

It's not too difficult to create a dynamic image for the browser based on an Image created on the server side, all you need is something to encode an Image into a JPG, GIF, PNG etc, and then make sure you add some elements to fool text recognition like lines and rotation.

I believe there should be sample code on creating dynamic images if you search the forum.

Nathan Pruett

Joined: Oct 18, 2000
Posts: 4121

They are called captchas... and the Wikipedia article has a link to a project called JCaptcha on SourceForge.

Write once, run anywhere, because there's nowhere to hide! - /. A.C.
Mirko Froehlich
Ranch Hand

Joined: Aug 21, 2000
Posts: 114
Thanks for the pointers. I actually came across the Wikipedia entry and the JCaptcha project shortly after I posted my message.

For some reason, information on this topic seems to be difficult to find without knowing the proper name of this technique (Captcha)...

I agree. Here's the link:
subject: image verification
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