disable image caching?

[bvogt]

using gd to dynamically build a bar graph. dynamic filename for the image, based on the ID on the db records for the data.

here's the problem: as a user adds data to the chart, they get a chance to "proof" the resulting image. They can adjust the image if there are any problems, which results in a new png file with the same filename.

To display the new png, however, one must force refresh.

I've tried all the typical HTML headers for cacheing, but these seem to all relate to HTML content and not img content.

Any workarounds?

Thanks!

[rehfeld]

send some no cache http headers

look at header()

[bvogt]

currently have:
<?
header("Expires: Mon, 26 Jul 1997 05:00:00 GMT");
header("Last-Modified: " . gmdate("D, d M Y H:i:s") . " GMT");
header("Cache-Control: no-store, no-cache, must-revalidate");
header("Cache-Control: post-check=0, pre-check=0", false);
header("Pragma: no-cache");
?>

This only works for HTML content, though -- image cacheing seems to be an entirely different issue.