Reflection:

Reflection is making a mirror image of an object around any axis. To understand the mechanism of reflection, let us assume the transformation matrix

Reflection about y-axis

Reflection about x-axis                               Reflection about x-axis and y-axis

Reflection about y = x-axis

Figure: Reflection about x-y Axes

If a and/or d are negative, reflection by means of an axis or plane occurs.

Let b = c = 0, d = 1 and a = - 1

then

∴  Reflection through y axis results. Likewise if a = 1 and d = - 1, then reflection through

x axis results. If a and d = - 1, after that reflection through origin results.

In reflection, only the diagonal terms are influenced.