What does this paragraph mean?
Detail in images require higher frequency basis functions.  The frequency in this case is measuring fluctuations in intensity as a distance is traversed.  With a lot of detail, a lot of fluctuations, thus higher frequency.
Tamp down the higher frequency and you lose detail, i.e. the image blurs.
The dampening is measured (described) best on a log scale.
Consider this answer Honey Mustard.