Banner PresencePLUS P4 COLOR Series - Manual (Page 204)

Adaptive
Select Adaptive when there are lighting changes that cause the acquired image to change.
Adaptive thresholding is a technique that is used to adjust the threshold for the BLOB tool based upon lighting changes
and image content within the ROI. It performs best if used with bi-modal images, which have a clear contrast in the
ROI. Adaptive thresholding chooses the current threshold value by converging to a value based on the average value
of the pixels above and below the previous threshold value; it will not move the value of the threshold above or below
the upper or lower limits.
Low Limit: Enter a gray scale value in this field, and the tool will not allow the Adaptive threshold to go below this
value.
Upper Limit: Enter a gray scale value in this field, and the tool will not allow the Adaptive threshold to go above this
value.
Reject Level: The Reject Level field is for bright Blobs only, and is used to narrow the range of pixel intensities to
consider in an inspection. Leaving the defaults at 0 for low and 255 for high will result in the tool taking into
consideration all gray scale levels in the ROI from 0 (black) to 255 (white). Note that the Reject Level field is visible
only when Bright bead type is selected.
Fixed
Select Fixed when the lighting and image content will remain relatively constant for all inspections.
If you select Fixed , you can also specify Threshold and Reject Levels.
Threshold Level
The Threshold Level (e.g., 141) defines the white/black cutoff point. Once a threshold is chosen, any pixels brighter
than the threshold become pure white while those darker than the threshold become pure black.
Reject Level
The Reject Level field is for bright Blobs only, and is used to narrow the range of pixel intensities to consider in an
inspection. Leaving the defaults at 0 for low and 255 for high will result in the tool taking into consideration all gray
scale levels in the ROI from 0 (black) to 255 (white). Note that the Reject Level field is visible only when Bright bead
type is selected.
Banner Engineering Corp. Minneapolis, MN USA 204
2/2010 PresencePLUS Software Tools