jQuery Plugin that does this?

Is there a jQuery plugin that allows this?

You could use a "tag" plugin to do something similar?

http://www.jpictag.com/demos/edition

Or

http://djpate.com/2011/01/14/jtag-a-jquery-plugin-to-tag-pictures-more/

You're looking at quite a bit of effort (and cpu power and thought) for very little gain. It essentially involves creating your own bit of javascript / jquery plugin.

But if you still wanted to go about doing it, you're going to need to load an image onto a canvas element, pull in its data using getImageData, and then use some pretty advanced OCR trickery to figure out where & what these letters are.

It's definitely possible if you've got the time - John Resig analyses a Greasemonkey script that used this technique (along with Neural Networks) to solve captchas here.