OCV Tool Parameters

OCV Tool parameters include controls for Defect Detection, Filtering, and Settings.

 

 

Defect Detection

Click the Defect Detection area of the OCV Tool parameters to display controls for Tolerance and Units (Percentage of total symbol size, or an absolute value in Pixels). You can also determine whether the tool bases defects on Total Residue Area or Largest Blob, or set it to Check Minimum Contrast, which rejects any symbol whose contrast falls below 50% of the trained symbol’s contrast.

 

 

Filtering

Click the Filtering area of the OCV Tool parameters to display controls for Minimum Symbol Size and Residue Cleanup.

 

Minimum Symbol Size allows you to set the minimum number of pixels required for a blob to constitute a symbol.

 

Residue Cleanup allows you to set the number of pixels to remove around the perimeter of each blob of residue. Increase this value if the size of symbols varies by a large amount.

 

 

Settings

Click the Settings area of the OCV Tool parameters to display controls for Polarity, Single Symbol, and AutoFind the Symbols.

 

The OCV Tool can usually detect polarity on its own, but when it can’t, set Polarity directly to Light on Dark or Dark on Light.

 

Enable Single Symbol if you want all features within the template ROI to be trained as one symbol.

 

Enable AutoFind the Symbols to search automatically for trained symbols. Disable AutoFind to save processing time if you are already using a Locate Tool.

 

 

Training the OCV Tool

The OCV Tool is trained in the same way as the Locate Tool.

 

 

 

You can then verify the quality of individual characters in the inspection area.

 

Hint: Click on individual letters to show their detailed results as in the example below, which shows an analysis of a symbol’s size and total residue area.

 

 

Note: When using the OCV Tool, you may see two additional boxes within the boundary ROI and outside the template ROI, as in the example above. This is normal and does not affect OCV Tool performance.

 

 

OCV Outputs

 

 

 

OCV Tool Advanced Parameters

 

The OCV string is found by first locating two characters in the string. Typically it is the first and last character. This parameter allows you to set which characters to use as locators.

 

AutoFind: Distance Tolerance: The string can have similar characters next to each other. This can cause the locate function to choose the wrong characters. By specifying the tolerance, the algorithm determines which character is correct by comparing the trained distance between the characters and the current distance. If the difference is less than the tolerance, that pair will be used for location.

 

AutoFind Pin 1 Index: Default is 0 for the first character.

 

AutoFind Pin 2 Index: Default is 999 for the last character.

 

Individual Symbol Search X and Individual Symbol Search Y: Once the general string is found, each character is located before comparison is performed. The following parameters set how far the algorithm will search for each character compared to its trained location. If the character spacing or vertical location vary widely, these parameters can be used to increase the search area. The larger the search area, the longer the tool takes to run. The default for Individual Symbol Search X and Individual Symbol Search Y is 3 pixels.