Set GPS Location on picture through JavaScript

Is it possible to set the GPS location of a picture through JavaScript? While using Google I found a lot开发者_运维问答 of ways to display this information but non on how to set it.

You can read EXIF data to get the lat/lng of an image but you certainly can't write it using Javascript

If you're open to writing a Firefox extension, you would have additional privileges, and you could figure out how to manipulate images locally.