I'm trying to apply image effects (curled shadow, in this case) to a 600x428px 600KB JPEG, and after selecting the effect, the spinner comes up, but never completes. Looking at top (this is Confluence 4.3 running on Ubuntu 12.04), there is a flurry of activity for about one second, then that is it, the java process just sits there at 0% CPU utilisation.
I've been able to apply the same image effect to small images without problem, so I'm wondering if there's a maximum size of image that the effects can handle?