Rockwell Automation 5370-OCR2 PAK - Manual (Page 59)

Chapter 5
Creating and Editing Fonts
5–24
If the OCR Tool fails to recognize a character:
When the system fails to recognize a printed character, it is because the
printed character differs substantially from the character used to teach the
character pattern. If this occurs, the following procedure should be followed:
1. Obtain a frozen image containing the character that is not recognized. If
the system is in run mode, exit run mode and enter setup mode.
2. Open the Toolset Edit panel and edit the OCR Tool.
3. Use the Threshold/Filter option to verify that the threshold is acceptable
for the image. If not, adjust the threshold so that the characters are well
separated from the background. If minor threshold adjustments are not
sufficient, it may be necessary to reduce the brightness variation of the
image.
4. Select the Character Size option, and verify that the character size is set
correctly for the characters. If not, adjust the character size (Refer to page
4–12 for a description of character size adjustment).
5. Select the Edit Font option and edit the character that is not recognized.
6. Use the Test option to determine whether the character correlates. If it
does not correlate at all, make sure that the character is not too close to
the edge of the OCR Tool’s processing window.
7. Place the character teach box around the printed character in the image.
Use the arrow buttons to finely adjust the position so that the character is
aligned as well as possible with the taught pattern.
8. Observe the areas where the printed character differs from the taught
pattern. Usually this will be around the edges of the character. By
placing more don’t-care pixels in this region, the system can be made
more tolerant of variations.
9. If the variation in the printed character is too great to accommodate by
adding additional don’t-care pixels to the taught character pattern, you
can make the system more tolerant of variations by decreasing the
correlation percentage of the taught character.