Rockwell Automation 5370-OCR2 PAK - Manual (Page 84)

Appendix B
Compensating for Lighting Variations
B–5
Method 2 – Brightness Compensation with Maximum Speed
Method 2 provides compensation for an overall increase or decrease in
brightness with minimum impact to inspection speed. Method 2 can also
compensate for uneven horizontal lighting across the character string, such as
printing on round bottles. This method requires a window to be placed in an
area of the image that will always be white. As in Method 1, Method 2
requires two Image Tools to preprocess the image for the OCR Tool.
•
The first Image Tool produces a background reference image.
•
The second Image Tool subtracts the background reference image from
the original camera image to produce a compensated image for the OCR
Tool.
To setup Image Tools for brightness compensation with maximum speed:
1. Add tools to the toolset as shown below. Note the S1, S2, and Dst
settings.
2. Use the P&P AOI 1 to position the AOI 1 window in an area of the
image that will always be white (as shown below). The size of AOI 1 is
not important.
3. Set Tool 1 Shape to Quad.