TWO DIMENSIONAL SIGNALS
Some 2D signals are $ \ \delta\left (\mathit{x}, \mathit{y}\right ) $,Rect$ \left (\mathit{x}, \mathit{y}\right ) $,Sinc$ \left (\mathit{x}, \mathit{y}\right ) $.One important property of 2D functions is that they are separable,when they are a product of two 1D signals.They are of the form :
$ \ \mathbf{f}\left (\mathit{x}, \mathit{y}\right )=\mathbf{g}\left (\mathit{x}\right ) $\mathbf{h}\left (\mathit{y}\right)