PRO Inspect
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6.1 Search
The purpose of Search is to locate and measure the quality of one or more previously trained features in an image.
The search operation measures the extent to which a feature in an image matches a previously trained model of that feature.
A feature is any specific pattern in an image. In most cases, you train a representative model from one image and use it to search for similar patterns in that image or in other similar images.
Search locates features by finding the area of the image to which the model is most similar.
Figure 6-1 shows a model and an image, and the areas of the image that are most similar to the model. An image and model similar to those shown in Figure
1 might be used to search for a single instance of a feature such as a fiducial mark on a printed circuit board.
Fig. 6-2 Search candidates
Model
Search Score
Search finds the location of a pattern in a search image based on a model image of that pattern. In addition to returning the location of the pattern in the search image, Search also indicates how closely the pattern in the search image matches the pattern in the model image by returning a score. The score indicates how close a match exists between the trained image and the image whose location was returned. Scores range from 0.0, indicating no similarity between the model and the feature, to 1.0, indicating a perfect match.
Origin point
Synthetic models
The location of the pattern is reported for a special point called “origin” . The origin is normally an arbitrary point of the pattern chosen at train time.
In alternative to models trained from actual images synthetic models are generated by assuming a certain shape of the pattern to be located such as a circle or an annulus. Synthetic models eliminate the need of manual training and provide the additional advantage of having a non arbitrary origin point. For example the origin of a circle is established in the center.
PRO Inspect
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Search tools supported by ProInspect
ProInspect supports the following types of Search tools:
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Search rect
(standard):
Standard search tool with rectangular model area and rectangular search area.
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Search circle
Search tool with circular model area and rectangular search area.
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Search annulus
Search tool with annular model area and rectangular
Search rect synth.
search area.
Search tool with rectangular synthetic model and rectangular search area.
Search circle synth.
Search tool with circular synthetic model and rectangular search area.
Search Settings
Programmable origin option
When this option is enabled, the model origin can be set graphically at train time. Otherwise the origin is set to the middle point of the model region.
Note: the model origin is an arbitrary point of the model region. The result of the search is the position of this special point in the run time image.
Pattern match limits
Accept -
Shape Index
Contrast
The acceptance level for the search score. Results with scores below this limit are not accepted.
A tolerance for the contrast of the pattern found relative to the model. Results with a contrast change higher than this tolerance are not accepted.
Search range
X, Y
Search range
The X, Y, in pixels, defines the area around the nominal position of the template in which the system performs the search.
Tolerances
X, Y
Tolerances
Skip results on edges
The tolerances for the search result. The tool fails if the position is found outside these tolerances.
An option to avoid considering results that are found along the edges of the search areas as these results are often unreliable.
PRO Inspect
Number of results
The maximum number of results to search and report..
Search results
Score
Contrast
X, Y
Match quality index. A value from 0 to 1 indicating the level of conformity between the model and the pattern found.
A measure of the relative contrast of the pattern relative to the model. 1.0 indicates a contrast equal to the trained pattern. Higher or lower values indicate higher or lower contrast.
Position of the pattern found.
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