Industrial Automation



Product serialization, data compliance, and label accuracy have been on everyone's lips these days. With manufacturers under obligation to meet new federal regulations for traceability initiatives in industries from aerospace and defense (DoD IUID) to medical device (FDA UDI), Microscan has been busy keeping up with the demand for barcode verification and label inspection training and solutions.  

If your company is concerned with product data integrity, whether in an effort to meet industry requirements, to avoid negative customer response, or to improve the efficiency of internal operations, your number-one insurance policy against bad data is to incorporate a verification and inspection technology. When it comes to ensuring accurate and quality barcodes, it is especially important to understand the difference between barcode reading and verification so you know what your goals are and that you are using the correct product to meet these goals.  

What is the difference between barcode reading and verification?

Barcode reading recognizes a barcode symbology (the type of barcode; i.e., UPC, QR Code, Code 128, etc.), analyzes the content of the code (extracts encoded data), and transmits the data to a computer or other external equipment. Reading a code is not the same as verifying that a barcode is accurate and high-quality - although some people buy readers for the purpose of performing barcode health checks, assuming, " If it reads, then I have a good code." This is false! The fact that a barcode reader is able to extract data from a code gives no indication of the code's print quality over time or across different barcode reading equipment. For instance, one person may use a barcode reader with advanced decode algorithms that is able to reliably extract data from a damaged code. However, this same code may not be readable to another vendor using different equipment.

Verification systems
measure the quality of a 1D barcode or 2D symbol by comparing what the verifier sees to the physical characteristics of an ideal, high-quality code. This comparison is made using agreed-upon barcode quality parameters (regarding a code's expected shape, skew, contrast, element size, and more). These parameters are regulated by barcode quality standards organizations (like ISO), and are intended to make sure that the barcode will be able to be read on the first attempt every time, regardless of what reader is used. A good verification system will ensure long-term readability and also alert you of the specific defects in your code so that you can make adjustments to whatever operation (code creation, printing, marking, or handling) that may be causing code quality issues.  

What are the things you need to verify about your barcode?  

The three important things to check when verifying barcodes are:  
1. Print quality  
2. Decodability  
3. Structure  


Print quality is all about the physical characteristics of a given code as compared to the physical characteristics of a theoretically perfect code.  

Questions that are addressed by print quality verification are:  

- Can the barcode reader tell what kind of symbology it is? (For example, a UPC.)  
- Does the code have the proper characteristics for its symbology type? (A UPC must have 30 bars and 28 spaces.)  
- Does the code have clearly-distinguishable characteristics? (Determined by measuring contrast, reflectance against a surface, quiet zone surrounding the code, etc.)  

Print quality issues occur when smudges, blemishes, or inconsistencies in printing prevent data acquisition devices (barcode readers or cameras) from extracting the encoded data. These issues can occur for a number of reasons. Low ink pressure can cause low contrast between the code and the surface, and bleeding issues can cause code elements to overprint or smear, causing no-reads. Movement of products during printing and variations in product speed can also cause a warped code, as can heat, water, or other environmental elements that may damage a code's physical appearance.

Note that barcodes are made up of black and white elements (lines for 1D linear barcodes like UPC and cells for 2D matrix symbols like Data Matrix). Both white spaces and black elements are equally important to reading the code. When reading a barcode, the barcode reader must be able to distinguish these elements and interpret their arrangement and thicknesses correctly.  

For example, with linear codes, there are 4 different possible line thicknesses that a barcode reader must be able to interpret. The skinniest line (what is known as the barcode's " X-dimension") will be referred to as " 1," the medium-sized line as " 2," the next largest line as " 3," and the thickest line as " 4." These thicknesses all indicate encoded data values that the barcode reader can extract. Although the barcode that you create on your computer might display the perfect thicknesses for these lines, bleeding issues caused by inconsistent ink during printing can make the lines bigger or spaces narrower, making it impossible for a barcode reader to properly interpret which line thicknesses it sees, resulting in a no-read.  


Once we are able to establish barcode print quality, we now need to know if a barcode will be able to be decoded properly. Looking at the image below, we can see that it is a Data Matrix symbol. The barcode reader can identify this symbol as a Data Matrix, and is able to distinguish its light and dark elements. If the light or dark elements of this symbol are too large or small, however, our barcode reader may be unable to extract its data properly.  

Problems with decodability can happen for a number of reasons. Modulation occurs when the dark elements of the symbol do not have a consistent value. This issue, like low contrast, is often due to inconsistent distribution of ink for printed codes or uneven abrasion for direct part marks. Issues with modulation may cause the barcode reader to " lose count" of the elements in a symbol, or interpret elements in the wrong sequence, making it impossible to decode the symbol accurately.  

Damage to the patterns of barcode elements, such as fixed pattern damage, can significantly undermine readability as well. In 2D symbols like the above Data Matrix, fixed pattern damage refers to missing elements in the symbol's " finder pattern" (the outermost rows and columns of the symbol), which includes the " L-pattern" (the solid left and bottom rows of symbol elements) and " clock pattern" (the elements on the symbol edges opposite the " L"). These patterns allow the barcode reader to interpret the barcode orientation and appropriately distinguish the number of element rows and columns for decoding. Obstruction of these symbol patterns by scratches, stains, debris, or other material can cause fixed pattern damage and render the barcode unreadable.  

For more information on these and other issues with barcode decodability, read our whitepaper outlining The Most Common Causes of Unreadable Barcodes.  

Back to our painting metaphor"¦ Just like a barcode reader or verifier uses physical elements of a code to extract encoded data (for instance, extracting a manufacturer ID number to tell us " Who is the manufacturer of this product?"), physical elements of the painting below can tell us who painted it. Compared to the parameters of style used by the artist, we can tell that it's a Picasso. Some of the criteria that help us to " decode" the painter include the color palette used, the structure of the painting, shapes and angles, brush strokes, the subject matter, and even a signature in the corner.


Verifying the structure of a barcode tells use whether the encoded data is formatted correctly (with the correct data elements, in the right order). For instance, you may have a quality barcode (it can be read by any barcode reader to extract data), but now we want to see if the data encoded within the code is GS1 compliant. Does the code have the correct Application Identifiers (AI), the correct amount of characters in the GTIN, the proper order of AI segments according to GS1 data formatting standards?

Speaking metaphorically, if our code were a painting, we would want to know, " is it valid?" Like a barcode verifier compares extracted data from a code against the required format outlined by barcode experts (like GS1), we can validate the integrity of our painting against expert opinion about what qualifies as an acceptable " Picasso" painting.

Just like a painting, the criteria that determine barcode print quality, decodability, and structure require highly detailed analysis. In more advanced forgeries, a painting may appear to the human eye to be authentic but, upon much closer examination, is found to be forged. That is exactly why automated barcode verification by specialized verification technology is so important. Verifiers use precision image processing and special algorithms built into their software to verify visual and encoded elements of a barcode, which would be extremely time-consuming for a human operator to reproduce by doing physical measurements of a barcode. With speed and accuracy, a verifier is able to catch discrepancies in code quality, decodability, and structure that may not be noticeable to the human eye.  

Do you need to verify your barcodes for quality and accuracy? Contact a Microscan Verification Expert and let us know how we can help you keep your codes up to code.  

For more great resources on verification, check out our latest educational whitepapers: Three-Step Verification for Lean Product Labeling

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