Fourier transform

Sensitivity peaks around 5 Hz , at the mean luminance used here (50 cd m−2) and decreases at lower or higher temporal frequencies. These data are well fit (black curve) by a model with only two temporal channels, compared with the multiple channels that support spatial contrast sensitivity.

Spatial frequency sensitivity provides an indication of a person’s ability to perceive visual information across the full visual spectrum, from fine to broad scale, and is measured with repetitive patterns of black-and-white bars.

The visual system, in other words, is less sensitive to very low spatial frequencies than it is to intermediate ones. As a result, there is a range of spatial frequencies, toward the center of the horizontal axis, where humans are maximally sensitive .