What is ISO/IEC 15416 and what does it measure?

What does ISO/IEC 15416 cover?

According to ISO’s public abstract, the standard specifies how to measure specific attributes of a barcode, how to evaluate them into an overall assessment of symbol quality, and what usually causes a poor grade, so users can correct it. It applies to symbologies with a reference decode algorithm that are read by linear scanning. The third edition, published in January 2025, replaced the 2016 edition.

According to GS1, the method grew out of 1980s work on the scan reflectance profile, was published as ANSI X3.182 in 1990 and then as EN 1635, and became ISO/IEC 15416 in 2000. GS1 states that the three are technically compatible.

What is a scan reflectance profile?

A verifier lights the barcode with light of a set wavelength and moves a small measuring spot, the aperture, along a line across the bars. At every point it records how much light comes back. Plotted against position, that record is the scan reflectance profile: high where the spaces are, low where the bars are. GS1 sums up the idea simply: an ISO/IEC verifier looks at the symbol the same way a scanner does.

Because one line can cross an unusually good or bad part of the code, the verifier grades several scan lines. The table follows the GS1 verification report for linear barcodes, with the causes GS1 lists for low results.

How are ISO/IEC 15416 grades expressed?

Every parameter on a profile gets a grade, and the profile takes the grade of its weakest parameter. GS1 describes the overall symbol grade as the average of the profile grades, written to one decimal place. According to GS1, an ISO/IEC verifier reports four passing grades, 4 to 1 in falling quality, and one failing grade, 0. The older ANSI method uses letters A to D for passing and F for failing, with the same thresholds; GS1’s DataMatrix guideline maps A to 4, B to 3, C to 2, D to 1 and F to 0, and GS1’s quick-reference table lists its usual minimum, 1.5, as grade C.

The grade depends on the materials as much as the printer. GS1 gives brown corrugated board as the worst case: its own reflectance is so low that even very dark ink cannot lift symbol contrast above grade 1. GS1 also sets a lower minimum, 0.5/20/660, for ITF-14 codes with a large X-dimension printed directly on corrugate.

What do aperture and wavelength mean in 1.5/06/660?

GS1 writes a minimum quality as g.g/aa/www: the minimum overall grade to one decimal place on the 4.0 scale, the effective measuring aperture in thousandths of an inch, and the wavelength of the light source in nanometres. So 1.5/06/660 means grade 1.5 or better, measured with a 6 mil aperture under 660 nm red light. GS1 specifies 660 nm, plus or minus 10 nm, for its barcodes.

The aperture has to suit the code’s narrowest bar. GS1 warns that too small an aperture exaggerates defects and too large an aperture smooths them out and lowers modulation, so a grade measured with the wrong aperture is misleading. That is why GS1’s tables set the aperture per application, alongside the grade.

Who uses ISO/IEC 15416?

• Printers and converters, to set up and control print runs.
• Brand owners, to show a barcode meets customer specifications before listing.
• GS1 member organisations, for verification services; GS1 South Africa states that it tests using ISO 15416 methods.
• Verifier makers; according to GS1, ISO/IEC 15426-1 sets the accuracy tests for linear verifiers, and GS1 offices supply calibrated test cards.

An in-line code reader answers a different question: does each code decode with the right content? See chapter 4 and our guide to barcode verification and grading.

What does an ISO/IEC 15416 grade not tell you?

GS1 lists the gaps itself. ISO verification does not measure dimensions, and most verifiers do not measure height. A verifier does not confirm that the human-readable digits match the barcode, or that the number is right unless linked to a database. A grade covers only the samples measured, and a perfect code can still be scratched, frozen or wetted later. GS1 verification reports therefore add checks such as X-dimension, height, quiet zones, human-readable text and company prefix to the ISO/IEC grade.