Verification – Easy as A, B, C…

Verification Theory
Verification…
As Easy As A, B, C…
Many terms...
…easy explanation
• ANSI -- American National Standards Institute
• X3.182 -- ANSI’s Print Quality Standard
• CEN -- Committee for European Normalization
• 1635 -- CEN’s equivalent to ANSI X3.182
• ISO/IEC SC31 -- International Standards Organization /
International Electrotechnical Council Subcommittee 31 on
Automatic Identification and Data Collection
• WG3 -- SC31’s Work Group on Conformance
• ISO/IEC 15416 -- ISO equivalent to ANSI X3.182
• SRP -- Scan Reflectance Profile… the basis for all X3.182 /
1635 / 15416 test measurements
• QZ, ERN, SC, etc. -- Test parameters found in X3.182 /
1635 / 15416
Why Verify?
“Verification” versus “Validation”
●
●
Validation is checking to see if the bar code
symbol will decode and if the data in it exists in
the database
Verification is checking the overall print quality
against a set of standards or specifications
Why Verify?
●
●
●
●
Without verification, bar codes entering the automatic data
collection system run the risk of not scanning efficiently (or at
all) or may contain substitution data errors
Quality standards being adopted worldwide such as ISO 9000
demand traceability and accountability
Bar code applications include symbol and format specifications
as part of quality determination
A point to remember… scanners are not verifiers. Scanners are
designed to read… verifiers are a quality control instrument
What to Verify
• Parameters that can be measured visually,
without using equipment
• Parameters that should be measured using
verification equipment
– Traditional Quality Parameters
– ANSI / CEN / ISO Bar Code Print Quality
Parameters
Human Readable Characters
0
01234 56789
5
Are the characters the correct size?
Is the placement in relation
to the bar code correct?
Symbol Placement / Location
Application guidelines
and specifications have
been put together to
guide you through the
proper placement of your
symbol… for your
specific package type
and use
Symbol Placement / Location
For symbols placed
on containers used
for shipping as well
as being scanned at
the point of sale,
logistic symbol
placement guidelines
should be followed
Bleach-O
64 oz.
6
14141 00086
VCR Player/Recorder
Qty: 1
6
14141 00086
9
9
Symbol Height / Truncation
• In POS scanning applications
– scanners read EAN/UPC symbols as two halves and then
piece the halves together into a complete number
– shorter symbols decrease the opportunity to get a good scan
• Do not truncate (shorten height)
– truncate only when there is no room for the full symbol height
left half
0
12345 67890
5
0
right half
12345 67890
5
Equipment Based Verification
Methodologies
• Traditional Analysis Parameters
• ANSI X3.182 - CEN EN1635 - ISO/IEC 15416 Bar Code Print Quality
What are Traditional Quality
Parameters?
Traditional - based on linear measurements of
bar/space widths as seen by the human eye,
reflectance values of background versus bar color
when measured through a red filter and the correct
data encodation.
0
1 2 3 4 5
6 7 8 9 0
5
Decode / Encodation
=
1A2B3C
Does the bar code pattern represent
the proper series of characters?
Contrast high enough?
Print Contrast Signal PCS = Refl.light – Refl.dark / Refl.light (minimum 75%)
0
01234 56789
5
0
01234 56789
5
Red on white looks OK to us, but not to the scanner
0
01234 56789
5
0
01234 56789
5
Average Bar Deviation
Represents aim bar width
Represents amount of gain
or loss allowable
Quiet Zones / Light Margins
QZ / LM
Allow for the appropriate quiet zones
QZ / LM
0
12345 67890
5
Clear areas around the bar code necessary for the scanner to properly
recognize and read the bar code. They are free of wording, graphics,
closures, perforations or scores.
Wide to Narrow Ratio
3:1
Ratio
Width of the wide elements when compared
to the width of the narrow elements.
Check Character for UPC/EAN
1. 0+2+4+6+8+0=20
(20 X 3 = 60)
2. 1+3+5+7+9=25
0
12345 67890
5
3. 60+25=85
Check Character = the number added to the sum of 85 is
a multiple of 10. The check number = 5
Example is a UPC Modulo 10 Check Character Calculation
What are ANSI/CEN/ISO
Quality Parameters?
ANSI / CEN / ISO - Evaluation based on how the scanning or
reading equipment ‘sees’ the bar code. Quality parameters
are calculated using reflectance values from the bar code’s
Scan Reflectance Profile (SRP).
Spaces
100% Reflectance
Quiet Zone
0% Reflectance
Quiet Zone
Bars
Verifier Apertures & Wavelengths
re
u
t
r
pe
h
A
t
eng
l
e
v
Wa
Verifier Apertures…
Aperture Diameter Too Large
Aperture Diameter Too Small
Recommended Aperture Sizes
‘X’ Dimension Range
●
●
●
●
0.0040” ≤ X ≤ 0.0070”
0.1016mm ≤ X ≤ 0.1778mm
0.0070” < X ≤ 0.0130”
0.1778mm < X ≤ 0.3302mm
0.0130” < X ≤ 0.0250”
0.3302mm < X ≤ 0.6350mm
0.0250” < X
0.6350mm < X
Aperture Size
●
●
●
●
0.0030” (3 mil)
0.0762 mm
0.0050” (5 mil)
0.1270 mm
0.0100” (10 mil)
0.2540 mm
0.0200” (20 mil)
0.5080 mm
Note: 6 mil (0.1524 mm) aperture specified for UPC/EAN
ANSI / CEN / ISO
Pass/Fail Quality Parameters
A(4) or F(0)
Edge Determination
● Minimum Reflectance
● Edge Contrast Minimum
● Decode
● Quiet Zone
●
ANSI/CEN/ISO
Graded Quality Parameters
A(4), B(3), C(2), D(1) or F(0)
Symbol Contrast
Modulation
Defects
Decodability
ANSI/CEN/ISO
Scan (SRP) Parameters
6
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...9 parameters
for each scan path
9
Edge
EdgeDetermination
Determination Pass
Pass==AA
Minimum
MinimumReflectance
Reflectance3%
3%==AA
Symbol
70%
SymbolContrast
Contrast
70%==AA
Edge
47
EdgeContrast
Contrast
47%=
%=AA
Modulation
55%
Modulation
55%==CC
Defects
17%
Defects
17%==BB
Decode
Pass
Decode
Pass==AA
Decodability
60%
Decodability
60%==BB
Quiet
Pass
QuietZones
Zones
Pass==AA
ANSI/CEN/ISO
Scan (SRP) Grades
6
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9
Lowest parameter
grade for each scan path =
Scan or SRP Grade
Edge
EdgeDetermination
Determination Pass
Pass==AA
Minimum
MinimumReflectance
Reflectance3%
3%==AA
Symbol
70%
SymbolContrast
Contrast
70%==AA
Edge
47
EdgeContrast
Contrast
47%=
%=AA
Modulation
55%
Modulation
55%==CC
Defects
17%
Defects
17%==BB
Decode
Pass
Decode
Pass==AA
Decodability
60%
Decodability
60%==BB
Quiet
Pass
QuietZones
Zones
Pass==AA
Courtesy of Uniform Code Council, Copyright © 1998, All Rights Reserved
ANSI X3.182 – EN1635 – ISO/IEC15416
Grading
6
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9
10 scan paths
for each symbol
ANSI/CEN/ISO
Symbol Grades
6
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9
The average of ten SRP
grades equals the symbol
grade
Scan
ScanGrade
Grade11 BB==3.0
3.0
Scan
ScanGrade
Grade22 CC==2.0
2.0
Scan
ScanGrade
Grade33 CC==2.0
2.0
Scan
ScanGrade
Grade44 BB==3.0
3.0
Scan
ScanGrade
Grade55 BB==3.0
3.0
Scan
ScanGrade
Grade66 BB==3.0
3.0
Scan
ScanGrade
Grade77 CC==2.0
2.0
Scan
ScanGrade
Grade88 BB==3.0
3.0
Scan
ScanGrade
Grade99 AA==4.0
4.0
Scan
ScanGrade
Grade10
10 BB==3.0
3.0
------------------------------------------------------------Average
AverageGrade
Grade 2.8
2.8or
orBB
ANSI/CEN/ISO
Grading
●
Scan (SRP) Grade
●
The ANSI/CEN/ISO Scan
or SRP Grade is the
lowest grade achieved of
all the ANSI / CEN / ISO
Parameters in a single
Scan or SRP analysis
●
Overall Symbol Grade
●
●
The Overall Symbol
Grade is based on ten
(10) scans (SRPs) and
the average of their
resultant Scan or SRP
Grades
The ten (10) scans are
for vertical redundancy
as well as statistical
stability
Minimum Grades are based
on your Application
• Example: The minimum UCC/EAN Symbol
Grades are…
Symbol
Application or Use
Minimum Grade
EAN/UPC
UCC/EAN-128
ITF-14
All applications
All applications
“X” < 25 mil (0.6350 mm)
“X” > 25 mil (0.6350 mm)
1.5 GPA (C)
1.5 GPA (C)
1.5 GPA (C)
0.5 GPA (D)
ANSI/CEN/ISO Print Quality
Flow Chart
EDGE DETERMINATION
Global Threshold (GT) = Rmin + (SC/2)
PASS or FAIL
REFLECTANCE MINIMUM
EDGE CONTRAST MINIMUM
Rs min - Rb max (worst pair)
Rmin ≤ .5* Rmax = PASS
Rmin > .5* Rmax = FAIL
≥ 15% = PASS
SYMBOL
CONTRAST
SC = Rmax - Rmin
≥
≥
≥
≥
70% = A/4
55% = B/3
40% = C/2
20% = D/1
< 20% = F/0
< 15% = FAIL
MODULATION
EC min / SC
≥ .70
≥ .60
≥ .50
≥ .40
= A/4
= B/3
= C/2
= D/1
< .40 = F/0
ANSI/CEN/ISO Print Quality
Flow Chart
DEFECTS
ERNmax / SC
DECODABILITY
≤ .15 = A/4
≤ .20 = B/3
≤ .25 = C/2
≤ .30 = D/1
> .30 = F/0
≥ .62 = A/4
≥ .50 = B/3
≥ .37 = C/2
≥ .25 = D/1
< .25 = F/0
DECODE
PASS or FAIL
PROFILE NUMERIC GRADE
SYMBOL GRADE CONVERSION
4.0 = A
3.0 = B
2.0 = C
1.0 = D
0.0 = F
3.5 to 4.0
2.5 to 3.4
1.5 to 2.4
0.5 to 1.4
less than 0.5
Print Quality Check List
Quality Factors
Edge Determination (Global Threshold)
Reflectance Minimum
Edge Contrast Minimum
Symbol Contrast
Modulation
Defects
Decodability
Decode
Quiet Zones (Clear Margins)
Print Contrast Signal (PCS)
Wide/Narrow Ratio
Average Bar Deviation
Check Character Calculation
Symbol/Human Readable Match
Symbol Location relative to Label
Label Size
Symbol(s) Placement on Product
ANSI,
or Trad’l
A
A
A
A
A
A
A
A
A
T
T
T
T
T
T
T
T
Visual
X
X
X
X
Verifier
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Test Card for ANSI / CEN / ISO Verifiers
• Calibrated Conformance
Standard is used to “verify
the verifier”
• Traceable to NIST
• Important training tool for
personnel in the correct use
of verifiers
Courtesy of Uniform Code Council, Copyright © 1998, All Rights Reserved
…and in the end.
• Though as highly technical, even confusing, in
nature all of this is… ANSI / CEN / ISO based
verifiers do all the work for you!
• In the end… the results from your verifier, with
the proper technical support, will help you to
maintain proper quality levels when printing.