It's possible to have such filters with Firefox as well if you use {filter:url(#svgFilter)} (see https://developer.mozilla.org/en-US/docs/CSS/filter). But I have to admit it's not as simple as webkit does.

An example: http://jsbin.com/ekekug/2 (only Firefox, and I didn't reproduce OP's tilt-shift effect)

Also, I'm wondering if it's not better to use Canvas for performance reasons.