making gifs automatically

Rick Shepherd R.Shepherd at
Thu Nov 7 00:34:25 CET 2002

Although this is likely a moot topic for now...

My original thought was that this is a very clever
idea.  However, now it occurs to me that a more
sophisticated robot of the future (if not of the present)
could probably use OCR (Optical Character Recognition)
to convert the gif back to text and still harvest the addresses.

These anti-spam battles take on a sort of "arms race"
nature;  also, they remind me of the Anonymous Call Rejection
(ACR) feature that I helped implement on DMS-10
telephony switches:  For example, if you, the called party,
subscribe to Caller ID features but the caller suppresses
his/her ID (using a blocking feature), then if you also subscribe
to the ACR feature and have it activated, your phone doesn't ring.
(I wouldn't be at all surprised if there's a feature to override this

Rick Shepherd

----- Original Message -----
From: "Olivier Gerard" <ogerard at>
To: "Seqfan Mailing List" <seqfan at>
Sent: Tuesday, November 05, 2002 7:27 PM
Subject: Re: making gifs automatically

> Le 05, N. J. A. Sloane écrivait:
> >
> > some one suggested replacing email addresses on my sequence database
> > by gifs with email address visible in the gif (to avoid robots
> > that harvest email addresses from the web)
> >
> > Does anyone know how to automatically take a short sentence, say
> >
> >       Jack Smith (js at
> >
> > and produce a gif which displays those words?
> >
> > Neil
> For similar tricks, I often use the gd/freetype libraries which are
> in various computer languages and operating systems.
> There are perl libraries available
> to interface with it (the server hosting the OEIS has mod_perl
> if I remember well).  In their standard version they produce PNG
> images (free equivalent of GIF).  They can be used in CGIs

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