ANSI/ISO Barcode Print Quality Grade

 

There are nine attributes (or parameters) that are evaluated through a single scan path, which are derived from a scan reflectance profile. Five of these attributes are subject to pass/fail criteria (A or F). Each of the remaining four attributes are graded (A, B,C,D,F). The overall grade for the scan reflectance profile (or single scan path) is the lowest grade for any of the nine attributes. The formal verification of a UPC symbol requires ten scan reflectance profiles spaced along the symbol. The overall symbol grade is obtained by averaging the grades of the individual scan reflectance profiles.

The overall symbol grade is obtained by averaging the grades of the individual scan reflectance. For example, if the ten individual profile grades were C, D, B, B, A, C, B, B, A, C; the symbol grade would be B. To be minimally acceptable, a UPC symbol must have a grade of C or higher. Below is an example of a 10 scan read.

Ansi.ISO.ten

In general, symbols with higher quality grades can be expected to scan more easily and quickly than lower quality symbols of the same magnification. Larger magnification, the absence of truncation, and high print quality, contribute to fast, effortless scanning. Symbols that fail verification may scan easily under ideal conditions, but badly or not at all in other environments. High productivity is synonymous with high symbol grades. Lower grade levels, although satisfactory, may cause failure to meet productivity goals in less than optimum environments.

Verification Scan Report

A scan report is the diagnostic output from a barcode verifier.  Scan Reports may be formatted differently, however they all must contain some key information:

scan.report

 

Difference between Scanning and Verifying a barcode

Being able to ‘scan’ a barcode with one scanner doesn’t mean the barcode is capable of being scanned by all barcode scanners and imagers.  Since a barcode will most likely be scanned a different of times within a supply chain it is imperative for the barcode to be read using different equipment.

The only way to ensure a barcode will be able to utilized by a variety of scanning equipment is to utilize the ANSI/ISO Barcode Print Quality Analysis.  The ANSI/ISO analysis evaluates symbols based upon the same mechanics that scanners use to read them.  This standard was introduced in the 1980’s and has become the common assessment used to grade the print quality of a barcode symbol.

Primary difference between a barcode scanner and verifier is that a verifier performs the ANSI/ISO Barcode Print Quality Analysis and confirms the barcode is formatted in accordance with specific barcode standards.

GS1 Certified Verification Equipment

GS1 Certified Verification Equipment has gone through a rigid certification process by the GS1 US.  This process includes a comprehensive review of all GS1 barcodes and relevant print quality standards.  Certified equipment has demonstrated it is traceable to the NIST Standard Calibration Standards.  This important for companies which need traceability and consistent testing results.

 

VIEW GS1 BARCODE VERIFICATION EQUIPMENT

 

ANSI/ISO Barcode Print Quality Parameters

There are nine attributes (or parameters) that are evaluated through a single scan path, which are derived from a scan reflectance profile. Five of these attributes are subject to pass/fail criteria (A or F). Each of the remaining four attributes are graded (A, B,C,D,F). The overall grade for the scan reflectance profile (or single scan path) is the lowest grade for any of the nine attributes. The formal verification of a UPC symbol requires ten scan reflectance profiles spaced along the symbol. The overall symbol grade is obtained by averaging the grades of the individual scan reflectance profiles.

Edge Determination

When the verifier is unable to find an appropriate number of bars and spaces, it reports an edge determination failure. The verifier must find 59 elements (30 bars and 29 spaces) for a version A.

There are several reasons why a symbol may appear to have too many or too few elements. Excessive bar growth (ink spread) may cause the smaller spaces to become so narrow that the verifier can no longer see them. In this case, the verifier would report fewer than 59 elements (for a Version A symbol). A different reason for failure is when one of the narrow bars is so weakly printed that the verifier cannot see it, resulting in 57.

Minimum Reflectance

The darkest bar must have a reflectance less than half of the background. This attribute is judged on a pass/fail basis. A failing grade for minimum reflectance will most often indicate that the bars should be printed darker or in a color that appears darker under red light.

Symbol Contrast

The blackest possible bars printed on the whitest possible surface would have a 100% contrast. Practical printing of the UPC symbol on commercial materials results in less than 100% contrast. When the contrast becomes too low, scanners may have difficulty distinguishing the bars from the spaces; thus, higher contrast is desirable. Symbol contrast is graded A through F.

A low contrast grade indicates that either the bars are too light (not enough ink or ink not dark enough), the background is too dark, or both. Because the measurements are made with red light, it can be informative to visually inspect the symbol through a red transparency. When viewed in this fashion, the bars should appear to be much darker than the spaces. Generally speaking, the background (spaces) should be white or one of the warm colors (red, orange, yellow) and the bars should be black, brown, blue or green.

Minimum Edge Contrast

The attribute of minimum edge contrast is graded on a pass/fail basis. This parameter measures the smallest value for edge contrast in a scan reflectance profile between a bar and space.

Modulation

Scanners and verifiers perceive the narrow spaces to be less white than the wide spaces. Similarly, but to a lesser extent, the narrow bars in a symbol look less black than the wide bars. This diminished intensity of narrow elements as compared to that of wide elements is called modulation.

The most probable reason for a low modulation grade is ink spread, which reduces the width and intensity of the single module spaces within the symbol.

Defects

Printing defects are of two types, voids and spots. Voids are light areas within the bars. Spots are dark areas in the spaces. Defects are undesirable because the scanner may become confused and think that a defect is an additional bar or space within the symbol. Symbols which yield profiles with poor defect grades can be examined with a good quality magnifier. The defects will be clearly visible. Usually, defects are voids that can be reduced or eliminated by increasing the amount of ink (or equivalent). Less often, excessive pigment or dirt may be deposited in the spaces, with resultant spots or inclusions.

Quiet Zone

UPC symbol design mandates a quiet zone, or area of uniform light contrast, adjacent to the outer edges of the left and right hand guard bars. Printing in the quiet zone, using overwrap in a manner that affects the restricted area, and placing the symbol near the edge of a package, are common causes for failure to meet quiet zone specifications.

Decode

Dimensional errors in printing a UPC symbol can make it difficult or impossible to scan. A verifier applies specific rules to the sequence of bars and spaces to decode them into a series of digits and guard bars. When the verifier is able to decode a symbol including its guard patterns, and when the check digit is consistent with the other 11 digits, the decode attribute passes with a grade of A; otherwise, the grade is F.

If all scan reflectance profiles for a symbol receive passing grades, but fail decode, the symbol is probably incorrectly encoded. It is reasonable to suspect that all or many of the symbols which were created by the same equipment in a similar time frame may also be defective. When only one out of several profiles fails to decode, the cause is usually a localized blemish in the symbol that can be spotted with a magnifier.

Decodability

Decodability is a graded attribute that measures how near the scan reflectance profile is to approaching decode failure. Symbols which are printed to a high degree of dimensional accuracy will exhibit high decodability grades.

One common reason for low decodability grades is ragged, uneven bar edges. Another reason for low decodability is excessive bar growth (ink spread), which also tends to adversely affect modulation and edge determination. The creation of barcodes using an improperly designed graphics based software system is a likely cause of low decodability.

  • UPC (GTIN-12)

  • ISBN/Books

  • Medical/UDI

  • Supply Chain

  • Assets/Inventory

  • Coupon

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UPC (GTIN-12)

There are a variety of different types of barcodes. However, the UPC (Universal Product Number) symbol is the most recognized barcode in the United States, since it appears on almost every retail product. The UPC symbol is the barcode representation of the GTIN-12 which consists of twelve numeric characters that uniquely identify a company’s individual product. The GTIN-12 number is part of the family of GS1 global data structures that employ 14 digits and can be encoded into various types of data carriers.

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ISBN/Books

A requirement for selling a book through booksellers, wholesalers, and distributors is the assignment of unique ISBN numbers for each title and for each book to be marked with a Bookland EAN barcode.

The Bookland symbol allows for encodation of ISBNs (the numbers publishers use to identify their products). Since an ISBN is unique to one particular title (or product), the corresponding Bookland EAN symbol is a title-specific marking which is unique for that title. For example, if a title is available in hard cover, soft cover and as an e-book, three unique ISBN Bookland EAN bar codes are required.

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Medical/UDI

The FDA UDI Mandate is part of a comprehensive healthcare traceability initiative to improve patient safety.  The Unique Device Identifier (UDI) requirement is rooted in holding each member of the supply chain responsible for ensuring each medical device is marked with a UDI barcode with data maintained on the FDA’s GUDID universal database.

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Supply Chain

Logistic barcodes such as the GS1-128 Shipping Label are used to track movement of a shipment within a supply chain.  Since suppliers are making shipments to a variety of trading partners it is essential to integrate the relevant standards and current technology.  The use of EDI and 2D barcodes which can encode much more data has transformed many supply chains.

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Assets/Inventory

The first step in designing an asset tracking system is to determine whether you are working with assets or inventory.  Assets are any items a company uses internally such as tools, equipment, furniture etc.  Inventory are items which are sold, distributed or used by a company.  The distinction between Assets and Inventory is essential in regards to how the items will be marked, scanned and stored.

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Coupon

The successful integration of GS1 DataBar Coupons has dramatically improved many promotions.  The interhent features including; value codes and automatic expiration date checking for retailers, has enabled more efficient redemption, much better security and better metrics to measure the performance of a campaign.

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Bar Code Graphics

Bar Code Graphics