Spatial frequency

Spatial frequency is a way of measuring how often something (usually patterns or shapes) shows up over a certain area. To understand this better, let's use an example. Suppose you have a wall with patterned wallpaper. The wallpaper has circles on it, and they repeat all over the wall. The spatial frequency would be the number of circles that you can see in one metre of wall. The more circles in one metre, the higher the spatial frequency.