> 1. If you really want to compute three Gaussian noise values per pixel,
> you should probably use the Ziggurat method for generating the random
> values; the ratio method is very slow. (That, and you should not
> do a divide per nextDouble()!)
> 2. There's absolutely no point in counting downwards in a loop that doesn't
> use its index; it doesn't buy any speed, and has not since sometime
> during the nineties. The compiler is able to do such transformations if
> it is a win.
"rgbnoise" is a straight port from gimp. We drop it for now if
consensus is that it is too slow.