Image Acquisitionand Proces

132 Image Acquisition Processing with LabVIEW
FIGURE 5.63 IMAQ convolute function.
5.8.2 PREDEFINED FILTERS
The Vision Toolkit has four built in predeÞned Þlter types: Gaussian, gradient,
Laplacian and smoothing. You may discover that these types will cover most of the
general purpose Þltering that you will require. The IMAQ Vision online help contains
a full list of the predeÞned Þlters available and their kernel deÞnitions(Figure 5.64).
FIGURE 5.64 Online Help — predeÞned Þlters.
5.8.2.1 Gaussian
As an effective noise minimization technique, the Gaussian Þlter is often referred
to as a “shaped smoothing Þlter,” although the blurring achieved is much less
pronounced than the latter. A typical 3 ¥ 3 Gaussian Þlter is:
1 2 1
2 4 2
1 2 1