User`s manual

iNspect Express User’s Manual405-00026-00
55Rev 1600; 12 July 2010
Advanced Properties – Threshold Tab
2D Barcode Threshold Properties
• Method – select the method for separating the barcode from the background. Threshold is dis-
abled after orientation and code type are selected or detected. Fixed uses a single number (Val-
ue). This method works best when lighting is uniform or does not change. Adaptive Global
calculates one threshold value for the whole Region, based on the intensities at the left and
right sides of the Region. This method works best when the lighting changes gradually and
evenly across the Region. Adaptive Local uses divisions or blocks within the Region to calcu-
late several threshold values. This method works best when lighting is uneven.
• Value – A specific threshold number, used to divide light and dark, for separating the barcode
from the background. Used for Fixed threshold.
• Calculation – the adaptive threshold (global or local) can be based on the mean (average) in-
tensity, or on the histogram of intensities.
• Horizontal/Vertical Blocks – set the number of divisions used in the Local Adaptive threshold.
The barcode Region is divided into this number of horizontal and vertical pieces (blocks). A
threshold value is calculated for each block. A high number increases the accuracy, but also
increases the execution time.