Click here to check out the online demo of this hack.
- The HTML 5 Canvas getImageData API is used to get at the pixel data from the Captcha image. Canvas gives you the ability to embed an image into a canvas (from which you can later extract the pixel data back out again).
- The pixel data, extracted from the image using Canvas, is fed into the neural network in an attempt to divine the exact characters being used – in a sort of crude form of Optical Character Recognition (OCR).
On the related note, sometime back I’ve written a post on “Is Captcha Secure?”