Tohle prej pomohlo. Resi to tam sice v JS, ale melo by se to dat pouzit i na PHP...
http://stackoverflow.com/questions/1077041/refresh -image-with-a-new-one-at-the-same-urlAs an alternative to...
newImage.src = "http://localhost/image.jpg?" + new Date().getTime();
...it seems that...
newImage.src = "http://localhost/image.jpg#" + new Date().getTime();
...is sufficient to fool the browser cache without bypassing any upstream caches, assuming you returned the correct Cache-Control headers. Although you can use...
Cache-Control: no-cache, must-revalidate
...you lose the benefits of the If-Modified-Since or If-None-Match headers, so something like...
Cache-Control: max-age=0, must-revalidate
...should prevent the browser from re-downloading the entire image if it hasn't actually changed. Tested and working on IE, Firefox, and Chrome. Annoyingly it fails on Safari unless you use...
Cache-Control: no-store
...although this still may be preferable to filling upstream caches with hundreds of identical images, particularly when they're running on your own server.
