Putting Code In Graphics

[bajanboost]

I have noticed that some people are able to make graphics that are dynamic, as in they contain code and when you save them, they become a static image.

Any idea?

Some Examples:
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http://www.danasoft.com/vipersig.jpg

<a href=http://profile.xfire.com/virology><img src=http://miniprofile.xfire.com/bg/bg/type/0/virology.png width=440 height=111></a>

[Robert Wellock]

Server-Side Generation via PHP scripts - it does the text before generating the PNG.

[FromU2ME]

You can create the image by coding in PHP, Perl, ASP, C etc. if you have an appropriate image creating program, such as GD (http://www.boutell.com/gd/).