Dear,

The frequency of some image signal was traditionally given by a number of cycles-per-millimeter (or per other spatial unit). This is a historical unit of measurement that is related to the invention of photography and comparing lenses.

If an image has large values at high-frequency components then the data is changing rapidly on a short distance scale. e.g. a page of text

If the image has large low-frequency components then the large scale features of the picture are more important. e.g. a single fairly simple object which occupies most of the image.

Thus low frequency correspond to slow varying information ( continuous surface) high frequency correspond to quickly varying information ( eg. edges)

source: http://dsp.stackexchange.com/questions/14259/how-we-define-frequency-in-an-image

Hi! May be this link will be useful!

http://dsp.stackexchange.com/questions/6452/how-to-extract-high-freqency-and-low-frequency-component-using-bilateral-filter