- If you want the timeout value to be "forever" then you can specify a
0 as the timeout value (or leave the parameter blank). To regenerate
the image you will have to remove the image files from the cache. This
removal could for example be handled by a nightly cron-job
- If you use images where you have enabled the anti-aliasing you
should strongly consider using caching since anti-aliasing is quite
time consuming compared to standard line drawings.