You might need to be further away (or try squinting). Spatial frequency is often reported in cycles/degree. A cycle is one complete set of transitions (light->

You might need to be further away (or try squinting). Spatial frequency is often reported in cycles/degree. A cycle is one complete set of transitions (light->dark->light) and a degree is the angular distance (1/360th of a circle; about the size of your thumbnail at arm's length). These units are handy since they don't depend on the thing you're looking at or how far away it is. Human spatial frequency sensitivity peaks between 1-10 cycles/degree, depending on how old you are, to see Ol' Abe, you ought to be far enough away that your thumbnail covers at least five of the tiles.