Captcha identify

[Skip Montanaro]

On Wed, Aug 13, 2014 at 2:44 PM, Joel Goldstick
<joel.goldstick at gmail.com> wrote:
> I wrote a sample form page with a simple math problem to solve -- 2 or
> 3 random small integers to add ...

I've also seen challenge systems where they present you with a small
set of images and ask you to select one with a particular property
(looks like a tennis racquet, shaped like a square, etc). While simple
to solve for most humans -- assuming they can read the language --
they would be difficult to solve by automated means.  You can also
magnify them for visually impaired or speak what they are on
rollover/hover, and don't require any typing. They can make cultural
assumptions (not everyone will know what a tennis racquet looks like,
for instance), so the images might have to be selected carefully.

Skip