A little project of mine

[GAMEchief]

What I've got to pull the pixel data thus far:

var c = document.createElement('canvas');
var ctx = c.getContext("2d");
var image = new Image();
image.src = "../../../dress-up/avatar/vend/10006349_tot_month.png";
ctx.drawImage(image, 0, 0, image.width, image.height);
var data = ctx.getImageData(0,0,image.width,image.height);

For example, executing it from the marketplace item listings page.

If you do image = document.getElementById ,
you get security errors because gaia doesnt like cross-origin data so you have to pull the url like I have done and set the src for it trk.

wat

User scripts don't have cross-origin security. Cut out your silly dev bologna part. Or export the security issues to a function within the user script. If needed, I can just do something like __LG__.get("id-here") that would just return the element with that ID. Should give you cross-script access to the element, I'd think.
But I imagine you could do all this on your own. Just make __LG__.botobject.functionThatCircumventsSecurity and call it whenever your external program needs it.

Also if you can read pixel color values and need help interpreting them, I can probably help contribute with that. I love programmatic image manipulation.