Speak softly in an unintelligible language and carry a big illustration, as my granddaddy used to say.
H's-1.png, is a single font with a single set of instructions being rasterized 3 different ways, aliased, greyscale and Cleartype (CT), in VTT.
H's-2.png, the same, but I commented out the IUP instruction that smooths out the untouched points.
H's-3.png the left is CT with the x hints turned on, while the right is CT again, but has the x hints commented out entirely.
What’s the difference you might ask, between CT with and without x instructions. . .