Spatial frequency in digital imaging

In mathematics, physics, and engineering, spatial frequency is a characteristic of any structure that is periodic across position in space. The spatial frequency is a measure of how often sinusoidal components (as determined by the Fourier transform) of the structure repeat per unit of distance .

That is, you are most sensitive for an intermediate range of spatial frequencies (around 4-6 cycles/degree ), and less sensitive to spatial frequencies both lower and higher than this, much like the audiogram.

As frequency refers to the (inverse of the) periodicity with which the sound sine wave repeats, the spatial frequency refers to the (inverse of the) periodicity with which the image intensity values change . Image features that change in intensity over short image distances correspond to high spatial frequencies.

Low spatial frequencies (LSF), conveyed by fast magnocellular pathways, provide a coarse information about a visual stimulus (e.g., the global shape and structure of a scene), whereas high spatial frequencies (HSF), conveyed more slowly by the parvocellular pathways, provide finer information about the stimulus (e.g., …7 May 2014