Image Acquisitionand Proces

Image Analysis 203
in the array would represent the edge pairs in the following order: AB, AD, AF, CD,
CF, EF, therefore the array element values would be as shown in Figure 7.58.
FIGURE 7.58 ROI intensity plot edge coordinates.
7.7.5 RAKING AN IMAGE FOR FEATURES
7.7.5.1 Parallel Raking
Just as a garden rake has several tines that create parallel lines in the dirt, an image
rake is a series of parallel line ROIs, deÞned by their start and end points, and the
relative distance between each line (Figure 7.59 and Figure 7.60).
Raking an image can be very useful when trying to Þnd a feature in an image.
Consider the example in Figure 7.59. If the part were shifted vertically, a single
horizontal line ROI may fail to locate the hole in the pin, whereas using a rake can
determine where the hole is, and its dimensions. IMAQ Rake is conÞgured using the
inputs in Table 7.6. The IMAQ Rake function returns an array of clusters, where
each array element corresponds to a rake line. The clusters contain an array of
clusters, each specifying the edge coordinates found along the rake line.
FIGURE 7.59 Parallel raking example.
FIGURE 7.60 Parallel raking example — wiring diagram.