[TYPO3-english] Images are not cached by the browser ... gifbuilder issue ?

[Christoph Stadler]

hello,

i noticed that my site is slowed down by the images which always seem to 
download on each page hit.

i have some text generated by gifbuilder as an image, i tried using png 
and jpg it doesn't make a difference.

when i hit reload on a page i can see the gifbuilder graphic 
reloading/redrawing but the other image on the page (logo) doesn't 
reload/redraw.

how can i make sure all images are cached by the client browser ? I am 
not using Expired headers on the server since my hoster won't allow it.