Image enhancement methods

SPATIAL DOMAIN METHODS:

The term spatial domain refers to the aggregate of pixels composing an image, and spatial domain methods are procedure that operates directly in this pixel

Image processing function in the spatial domain may be expressed as

  g(x,y) =T[f(x,y)]

Where f(x,y) is the input image and g(x,y) is the processed image, and T is an operator on f, defined over some neighborhood about(x,y) 

FREQUENCY DOMAIN METHODS:

The foundation of frequency domain technique is the convolution theorem .Let g(,y) be an image formed by the convolution of an image f(x,y)and a linear position, position invariant operator h(x,y) that is, g(x,y) = h(x,y) * f(x,y)

  Then from the convolution theorem, the following frequency domain relation holds:

  G( u,v) = H (u , v)F(u , v)

Where G,F &H are the Fourier transforms of g,h &h respectively.