Error Correction & Data Integrity

인쇄 품질과 오류 정정: ISO 15415 등급

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ISO/IEC 15415 print quality grading for 2D symbols. Modulation, fixed pattern damage, and minimum grade requirements.

  
  

    
  








  
  

    
    
      
      
  1. 
        Print Quality and Error Correction: ISO 15415 Grading
      
    2. 
      
      
  2. 
        The Grading System
      
    3. 
      
      
  3. 
        Quality Parameters
      
    4. 
      
      
  4. 
        Minimum Requirements by Industry
      
    5. 
      
      
  5. 
        Improving Print Quality
      
    6. 
      
      
  6. 
        Key Takeaways
      
    7. 
      
    

  









  
  

  
  

    
    

      

ISO/IEC 15415 defines a standardised quality grading system for 2D symbols including QR codes. Understanding these grades helps ensure your printed QR codes meet reliability requirements, especially in regulated industries.


The Grading System


ISO 15415 assigns a letter grade (A through F) or numeric grade (4.0 to 0.0) based on multiple quality parameters. Each parameter is graded individually, and the overall grade is the lowest individual grade.






Grade
Numeric
Quality






A
4.0
Excellent




B
3.0
Above average




C
2.0
Minimum acceptable




D
1.0
Below standard




F
0.0
Fail






Quality Parameters


Decode: Can the symbol be decoded? Binary pass/fail.


Symbol Contrast: The difference between the darkest and lightest modules. Minimum contrast of 20% is required for Grade C.


Modulation: Consistency of contrast across the symbol. Uneven printing, fading, or ink spread reduces modulation.


Fixed Pattern Damage: Integrity of finder patterns, timing patterns, and alignment patterns. These structural elements must be clearly defined.


Axial Non-Uniformity: Difference between horizontal and vertical module dimensions. Excessive stretching in one direction reduces this grade.


Grid Non-Uniformity: How well the module centres align with the expected grid positions. Distortion from printing on curved surfaces or printing misalignment reduces this grade.


Minimum Requirements by Industry






Industry
Minimum Grade
Standard






Healthcare (UDI)
C (2.0)
FDA 21 CFR




Automotive (AIAG)
B (3.0)
AIAG B-11




Aerospace
B (3.0)
ATA Spec 2000




Retail (GS1)
C (2.0)
GS1 General Spec






Improving Print Quality


    

  • Use high-resolution printing (300+ DPI for small codes)
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  • Ensure adequate contrast between dark and light modules
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  • Maintain the quiet zone (4 modules minimum)
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  • Avoid ink bleed by using appropriate paper and ink combinations
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  • Test with a verifier, not just a scanner (verifiers measure quality; scanners just decode)
    • 



Key Takeaways


    

  • ISO 15415 grades QR code print quality from A (4.0) to F (0.0)
    • 

  • The overall grade equals the lowest individual parameter grade
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  • Regulated industries require Grade B or C minimum
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  • Print quality directly affects error correction demands
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  • Use a verifier (not just a scanner) for quality assessment
    •