What is the difference between a one dimensional and a two dimensional signal?

If a signal depends on only one variable then we call it one dimensional, and if a signal depends on two variable we call it a two dimensional signal.

But when we represent an one dimensional signal, we use two axes(amplitude vs. time). In case of a two dimensional signal, we use two axes (for example, the x axis and the y axis in an image).

How can I understand the difference between a one and two dimensional signal?

• No, when you plot a two-dimensional signal, you use three axes: $x,y$, and amplitude. Feb 10 '14 at 22:18

In one dimensional signal $f(t)$, the amplitude $y=f(t)$ is the dependent variable (output), and there is only one independent variable $t$.
In two dimensional image $f(x,y)$, the two independent variables are $x$ and $y$, and the dependent variable $f$ is also called intensity. If you want to make it similar with amplitude vs time plot as you do with one dimensional signal, you can plot a intensity vs x vs y scattered dots with three axis as well.