Editing Unsharp masking (section)

== Implementation ==

In the example below, the image is convolved with the following sharpening filter:

'''Sharpen filter'''
<math display="block">
\begin{bmatrix}
\ \ 0 & -1 & \ \ 0 \\
-1 & \ \ 5 & -1 \\
\ \ 0 & -1 & \ \ 0
\end{bmatrix}
</math>

This matrix is obtained using the equation shown above under [[#Digital unsharp masking]], using a uniform kernel with 5 pixels for the "blurred" image, and 5 for the "amount" multiplier:

<math display="block">
\begin{bmatrix}
0 & 0 & 0 \\
0 & 1 & 0 \\
0 & 0 & 0
\end{bmatrix}
+
\left(
\begin{bmatrix}
0 & 0 & 0 \\
0 & 1 & 0 \\
0 & 0 & 0
\end{bmatrix}
-
\begin{bmatrix}
0 & 1 & 0 \\
1 & 1 & 1 \\
0 & 1 & 0
\end{bmatrix}
/5
\right) 5
=
\begin{bmatrix}
\ \ 0 & -1 & \ \ 0 \\
-1 & \ \ 5 & -1 \\
\ \ 0 & -1 & \ \ 0
\end{bmatrix}
</math>

The sharpening effect can be controlled by varying the multiplier. The value of 5 was chosen here to yield a kernel with integer values, but this is not a requirement for the operation.

<gallery widths="400px" heights="263px" perrow="2">
File:SharpenCarExample.png
File:SharpenCarExample2.png
</gallery>

The second image has been sharpened twice as much as the first.