On 6/11/07, Jim Lucas <[EMAIL PROTECTED]> wrote:
Tijnema wrote:
> On 6/11/07, Robert Cummings <[EMAIL PROTECTED]> wrote:
>> On Mon, 2007-06-11 at 10:38 -0400, tedd wrote:
>> > Gnag:
>> >
>> > I know we can beat this thing to death, as we have in previous
>> > threads and I don't anyone wants to travel previously traveled ground.
>> >
>> > However, Rob said:
>> >
>> > "A good captcha will try to exploit a computer's weaknesses."
>> >
>> > So, let's expound on that -- what do you consider to be a computer's
>> weakness?
>>
>> Well for instance as humans we can fairly easily recognize similar
>> shapes. We can recognize an apple whether it is red, green, yellow, has
>> a stem, has a leaf, is half eaten. A computer might recognize a circle,
>> and might guess that the circle is an apple based on further analysis.
>> But we as humans could recognize it as an apple even if we stretched it
>> a bit so it was no longer circular, or as I said, if it was a crescent
>> because someone had taken a huge bite out of it. This is something
>> humans excel at... inferring information from similar previous
>> experiences.
>>
>> Taking the image captcha to a different level, one could combine our
>> ability to understand language as well as imagery. For instance we could
>> have an icon repository of animals, vehicles, plants, etc (very obvious
>> ones anyways). Then to create a captcha we could randomly select X
>> icons, slightly morph them to spoof matching them within the captcha
>> image itself, then ask:
>>
>> What animal do you see in the above picture?
>>
>> I think someone already said microsoft or someone does something
>> similar. The principle is that we know what generally constitutes an
>> animal and a computer does not. Similarly, an audio complement would be
>> to have a background sound of maybe low level radio chatter overlaid
>> with the sounds of various everyday items... then one could ask:
>>
>> What did you hear ringing?
>>
>> Possible answers... a bell, the telephone, an alarm, etc.
>>
>> The problem then becomes an issue of people who can't spell or are
>> terrible at recognizing everyday things.
>>
>> Cheers,
>> Rob.
>
> Server builds up a database of pictures, client does the same with MD5
> check, and problem solved...:)
>
> Tijnema
>
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.
--
Jim Lucas
Convert image to fixed width + fixed height + default depth, then do
some work on it :P
Tijnema
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