HandHeld Entertainment Quick Check PC600 - Manual (Page 39)

A ≥ 70%
B
≥ 60%
C
≥ 50%
D
≥ 40%
F < 40%
Defects are voids (light areas) found in the bars or spots (dark areas) found in
the spaces and quiet zones of the code. According to the ISO/IEC print quality
guideline, each element is individually evaluated for its reflectance non-
uniformity. Element reflectance non-uniformity is the difference between the
highest reflectance value and the lowest reflectance value found within a given
element. Many elements will have zero non-uniformity. Defects are measured
as the maximum Element Reflectance Non-uniformity (ERNmax) divided by
Symbol Contrast. Defects is a graded parameter.
Defects = ERNmax/SC
A
≤ 15%
B
≤ 20%
C
≤ ≤ 25%
D
≤ 30%
F > 30%
Decodability, which can also be referred to as ANSI Peak Decodability, is a
graded parameter. Different decodability calculation methods are needed for
each type of symbology being tested, but the concept is basically the same for all
symbologies. Decodability tests for consistency in element widths throughout the
bar code and compares the readability against a reference decode algorithm.
Decodability measures the amount of “safe” margin left for the reading process
after any errors in the printing of the bar code. The higher the percent, the higher
the grade and thus the larger the margin for the scanning system.
For instance, in Code 39 there are two element widths, either wide or narrow.
Decodability looks for wide elements to be the same widths and likewise all
narrow elements should be the same widths. It also looks for sufficient difference
in the measured or perceived wide and narrow elements. This is controlled by
the wide to narrow ratio, and ISO/IEC terms this as Reference Threshold.
Decodability measures this printing accuracy and compares it to how a scanner
would be able to read the bar code against a reference decode algorithm. The
result is the available margin for the reading process.
Decode is simply whether the bar and space pattern matches a valid symbology
based on the decode algorithm. If a symbology is not enabled in Quick Check
®
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