Re: Going from simple to super CAPTCHA

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On Mon, 2007-06-11 at 18:57 +0200, Tijnema wrote:
> On 6/11/07, Jim Lucas <lists@xxxxxxxxx> wrote:
> > Tijnema wrote:
> > > On 6/11/07, Robert Cummings <robert@xxxxxxxxxxxxx> wrote:

> >
> > not if you are morphing/changing the image each page load.
> >
> <snip>
> >
> > remember, change height, width, color depth, plus all possible morphing and you are talking about a
> > lot of images.
> >
>
> Convert image to fixed width + fixed height + default depth, then do
> some work on it :P

A lot of people have already commented on why you can't provide the
answers in a radio or select list so I want answer those again. As
Others have already mentioned it's not an easy task to fingerprint the
images either since there are multiple problems at play for someone
attempting to do so. First off, we are using multiple backgrounds with
the icons placed on the backgrounds. To fingerprint you need to know
what the icons are on the background. You can't just fingerprint the
entire CAPTCHA because you the backgorund can change and so too can the
order and position of the icon. Additionally, by distorting the icon to
some degree, varying blending with background, colour, softness,
pixelation, etc the entire image becomes unique. Also even if for some
ungodly reason two images were generated with the exact same fingerprint
(unlikely as hell), the question might be different. One question might
ask what animal do you see? The other might say how many fish do you
see? As such there are multiple solutions to a single CAPTCHA but only
one is the answer based on the challenge posed.

Cheers,
Rob
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