Image Processing Reference

In-Depth Information

Fig. 5.7
The principle of correlation, illustrated with a 3

×

3kernelona6

×

6image

}

SetPixel ( output ,

x,

y,

temp );

}

}

When applying correlation, the values in the output can be above 255. If this is

the case, then we normalize the kernel coefficients so that the maximum output of

the correlation operation is 255. The normalization factor is found as the sum of

the kernel coefficients. That is
x
y
h(x,y)
. For the left-most kernel in Fig.
5.6

the normalization factor becomes 1

+

1

+

1

+

1

+

1

+

1

+

1

+

1

+

1

=

9, and the

resulting kernel coefficients are 1
/
9 as opposed to 1.