What are the Differences Between Barcode Quality Software and Barcode Verification?

Standard-Barcode Grading vs Barcode Grading Large

Barcode verification is the process of grading the quality of codes to globally accepted ISO standards using a device called a barcode verifier. Because the verification process is so regulated, users can rely on consistent results from device to device. An increasing number of industries require compliance to ISO or industry application guidelines that can only be met with ISO-compliant barcode verifiers like DataMan 8072V and DataMan 475V with ISO-compliant lighting. However, not all applications are able to use ISO-compliant verification due to mounting restrictions or barcode placement.

Many producers of barcode readers often provide simple code quality feedback using barcode quality software. Companies will base their grading methodology on the ISO standards for barcode grading giving an overall grade but often only picking and choosing some quality parameters to grade.

Results can vary from company to company because each uses their own proprietary algorithms to generate results. This can create discrepancies from line to line and company to company leaving room for doubt. The software certainly aids against time and resources being wasted printing damaged codes that are discovered too late. Barcode quality software can be ideal for users trying to control their process internally. Issues with the method only arise when codes are intended to be utilized by outside organizations. This is because reading algorithms for every reader are different; essentially what can be read by one scanner can not always be read by other scanners. It can become very difficult to gauge readability and ultimately prevent problems with chargebacks etc., using only barcode quality software.

For producers using barcode quality software or validation whose codes are still sometimes unreadable down the line, a verifier can provide additional protection and reassurance. To be considered a verifier, ISO requirements must be met thus standardizing verifiers from brand to brand. Example requirements listed in ISO 15426-1 and ISO 15426-2 are to, checks all quality parameters, uses a specific lighting set-up, and requires regular calibration.

Until now, these have been the only two options for barcode quality control, contract compliant verification or barcode quality software. Unfortunately, sometimes it is simply not possible to use a verifier for an application. It could be that there are space constraints imposed by some automated machinery where the distance and angle between a reader and a code are inconsistent with the standard verifier setup. These environments demand an alternative approach to producing consistent, well-defined, and broadly understood results similar to those produced by a verifier. Cognex offers a middle road approach called, Standards-based grading.

screenshot of verification software detailing grade parameters

Grade Reporting Format

  • The formal grade is written in a single line starting with the overall grade value followed by the aperture size, light wavelength, and lighting angle used.
  • The verification grade is shown as a letter grade. The letter grade is based off a calculated numerical value that works similar to a GPA, a 4.0 is an “A”, 3.5 -2.5 is a “B” and 2.5-1.5 is a “C”. 
  • Using a different aperture size or lighting angle can give drastically different results.
WHAT IS STANDARDS-BASED GRADING?

Standards-Based Grading (SBG) is a software feature key that can be preloaded or activated on select DataMan fixed-mount barcode readers to grade the quality of 1D and 2D codes while codes are being read. SBG uses the same verification grading algorithms, calibration process, and software user interface as DataMan verifiers but does not include the fixed angle lighting required in the International Organization for Standardization (ISO) guidelines. SBG is ideal to use when existing barcode quality software, such as process control metrics (PCM), is not reliable enough, and ISO compliance is not required or possible.

SBG 411

  • Next best thing to verification for real time code quality assurance
  • Offers lighting and working distance flexibility 
  • Includes advanced grading algorithms and calibration 
  • Auto-generates code quality reports

STANDARDS-BASED GRADING VS BARCODE VERIFICATION

Standardization that makes verification results from verifier to verifier more consistent. However, it can also put limitations on the type and placement of barcodes that can be verified. Standards-Based Grading is a way to get the reliability of ISO-compliant verification without the limitations.

Standards-Based Grading, or SBG, is a feature key add-on that can be activated for qualifying DataMan fixed-mount readers. SBG uses the same verification algorithms and software user interface as the rest of our verifier product line, with one key difference: lighting. Both ISO 15426-1 and ISO 15426-2, the standards that define verification manufacturing, have lighting angle requirements that also define an allowable working distance and presentation angle. By removing the lighting attachment component, users can create a custom lighting set up, often with off the shelf lights, that works for their specific application needs. Another benefit is that a liquid lens can be used, expanding the field of view and depth of focus capabilities and in addition to adding personalized lighting for your application.

Removing the lighting attachment does take away the ability to claim ISO compliant verification and is shown by a slight alteration in the grade report format. To avoid confusion, parameters that are not conforming, such as lighting and aperture, are not reported. Setting up the lighting as closely as practically possible to a standard verifier setup, will increase correlation between compliant verification results and SBG results.

A key component to stable verification results is ensuring that the unit is calibrated, and the software is using the appropriate standard reference decode algorithms for the symbology type. This is a crucial way that verification differs from basic code quality software. However, since Standards-Based Grading is essentially the same dependable verification software Cognex is known for, these two vital features are included, making the results correlate closely to true verification. Additionally, users will also have access to the same detailed diagnostic information and reporting features.

STANDARD REFERENCE DECODE ALGORITHM

  • The decode algorithm listed in the ISO standard for each symbology type.
  • The most simplistic decode algorithm for that symbology.
  • Most barcode readers brands develop their own powerful decode algorithms that can handle damaged or defected codes.
  • Verifying is a way to help guarantee that all readers, even without sophisticated algorithms, can decode the code.
  • Traditional verifiers will test for Decode first and upon failure does not continue with the verification process.
  • Cognex verifiers will provide quality parameter grading even if a code fails for decode giving users an idea of where to start to improve code quality.

STANDARDS-BASED GRADING VS BARCODE GRADING SOFTWAREgraph comparing the features of SBG and verification readers

With SBG, the reader can be calibrated to unify the cameras measurement of reflectivity levels and all ISO quality parameters are reported.

Unlike SBG, most barcode grading software such as Process Control Metrics (PCM) do not have a calibration process, follow the ISO grading algorithm requirements, or report every quality parameter. While barcode quality monitoring software results can provide a good idea of code quality, the results can also vary significantly between setups and hardware used.

Barcode grading software does give users an easy setup as it is usually a feature that is turned on to an existing reader. There are no specific lighting requirements and minimal mounting restrictions. Another benefit is cost, as most barcode reading companies include a form of barcode quality monitor software free of charge.


ISO COMPLIANT VERIFICATION REQUIREMENTS AT A GLANCE

For 15426-2 2D Matrix Codes the verifier must

  • Accommodate Reflectance Calibration based on two points (Rmax and Rmin)
  • Collect reflectance measurements 20X past the quiet zones
  • Establish a reference grayscale image and binarized image as described in ISO-15415
  • Decode these images according to the reference decode algorithm spelled out in the bar code specification
  • Report individual values for each of the grades spelled out in ISO-15415
  • Determine and report an overall symbol grade
  • Report the decoded data
  • Must be able to conform to a conformance test using industry standard test card(s) (Rmin & Rmax +/- 5%) (Decodability +/- ,08) (Defect +/- ,08) as well as other manufacturer test symbol values on the test card.

For ISO 15426-1 a compliant verifier must

  • Be able to be calibrated with two calibration points (Rb & Rs)
  • Collect reflectance measurements across multiple scans
  • Create an SRP
  • Analyze the SRP
  • Report Individual SRP scan grades 
  • Determine an overall symbol grade based on averages of the individual SRP grades and include aperture and wavelength in the overall grade
  • Report Data
  • Report all symbol characters (Function One, Code 128 encoding structure, etc.)
  • Must be able to conform to a conformance test using industry standard test card(s) (Rmin & Rmax +/- 5%) (Decodability +/- ,08) (Defect +/- ,08) as well as other manufacturer test symbol values on the test card.
WHICH OPTION IS RIGHT FOR MY APPLICATION?

Codes that will be used in an industry with an application standard will most likely list if ISO compliant verification is required. If no application standard is attached to the codes being produced, consider what form vendors and customers are using and how results will be compared. If may be worth the extra upfront expense to ensure codes are graded in a standardized process to eliminate accuracy debates down the road.

For some applications speed and space restraints will make using an ISO compliant verifier impossible. So, the only option is to turn to a Standards-Based Grading or Barcode Quality Software solution. Keep in mind the best barcode quality solution for may not be just one of these three options, instead it could be using a combination of all three.

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