Does anyone know how to code web browser plug-ins?
or point me to some info about programming plug ins

Ive looked everywhere and cant find what im looking for. I dont want an applet. What i need to do is when a user opens an html page, the plugin should parse all images and change the image if necessary. Then display the image to the user.

Is this possible?
Is this done with a plug in or something else?

Thanks

Hagai