First:  Can we use over 100% CPU?
	The way top defines it, yes

Image filters, part 2:
	What exactly is an image?
		A bunch of numbers...
		RGB for each pixel
		An array of unsigned char

So to find a pixel, it's at 3x the index
	width and height

How to convert image coordinates to an index
	We should be able to make a square or something on it
	Maybe add an image border

Detecting things: 
	Let's make a flashlight effect

This is "embarrassingly parallel"

What's NOT?
	Quicksort parallel example

Primes:
	Higher numbers are harder
	Numbers are asymmetrically harder
		Some numbers are easy to eliminate (example:  All evens)
	Result reporting, and hotspots
		All threads may need all sets of results

Image filter example:
	"greenness" index
	Map/Reduce may be appropriate here

mutex trylock vs. lock
	If you had something else to do anyway
	Can keep a queue of per-thread results