Posted by Dave M G on 10/03/90 11:36

PHP General List,

This is something I tried to find on Google, but I'm hindered by not
knowing the proper terminology.
On many sites that have contact or registration forms, they have a
small image file with a randomly generated number shown in a distorted
graphical fashion that is hard for a computer to scan and read.
The purpose is that the site visitor has to type in the numbers into a
field, in order to verify that it is, in fact, a human filling out the
form.
First, is there a term for these kinds of images, or that kind of
verification system? What would be the best search terms to look for
source scripts?
Second, can anyone recommend a resource for that kind of PHP script. If
I really worked at it, I could probably write the script to generate a
small PNG image with a random number in it. But I haven't the faintest
clue how to distort it so it's only legible to humans, nor how to
correlate the image with a number that a user inputs into a form field.

Any advice would be much appreciated.

--
Dave M G

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