This document summarizes a study evaluating various spectrophotometers for color management. It finds that newer instrument types and those receiving regular maintenance are more accurate. Instrument brand and age also impact results, with some brands performing better than others and older devices being less reliable. The study concludes that averaging multiple measurements improves accuracy and that technological advances may lead to light sources better suited for color measurement.

1. Working together toward greater efficiency
Practical Evaluation of
Spectrophotometers for Color
Management Purposes
Fons Put
VIGC - 26/05/2009

2. Introduction
• Flemish Innovationcenter for Graphic
Communication
Contents
• Introduction
• Color Measuring
• Spectrophotometers
• Conclusions
© VIGC - 7/09/2009 Practical Evaluation of Spectrophotometers for Color Management Purposes 2

3. Introduction
• Do we understand the printing proces?
Contents
• Introduction
• Color Measuring
• Spectrophotometers
• Conclusions
© VIGC - 7/09/2009 Practical Evaluation of Spectrophotometers for Color Management Purposes 3

4. Introduction
• Do we understand the printing proces ?
Contents
• Introduction
• Color Measuring
• Spectrophotometers
• Conclusions Original Reproductions
© VIGC - 7/09/2009 Practical Evaluation of Spectrophotometers for Color Management Purposes 4

5. Introduction
• Process control
• ISO standards (TC130)
• ISO 12647-2 (Print)
• ISO 12647-7 (Proof)
• ISO 3664 (Visual comparison Print-Proof)
• Measurement strips
• Print certification
• Proof validation
Contents
• Introduction
• Color Measuring
• Spectrophotometers
• Conclusions
© VIGC - 7/09/2009 Practical Evaluation of Spectrophotometers for Color Management Purposes 5

6. Introduction
• Process control
• Measurement Reports
• ISO 12647-2 (Print)
Contents
• Introduction
• Color Measuring
• Spectrophotometers
• Conclusions
© VIGC - 7/09/2009 Practical Evaluation of Spectrophotometers for Color Management Purposes 6

7. Color Measuring

8. Color Measuring
• What can be measured in the printing
process?
• The intensity of radiated light
• Unit: The CANDELA
• Derivatives: Density, CIELab, brightness,…
Contents
• Introduction
• Color Measuring
• Spectrophotometers
• Conclusions
© VIGC - 7/09/2009 Practical Evaluation of Spectrophotometers for Color Management Purposes 8

9. Color Measuring
• Color measuring devices
• Concept
Contents
• Introduction
• Color Measuring
• Spectrophotometers
• Conclusions
© VIGC - 7/09/2009 Practical Evaluation of Spectrophotometers for Color Management Purposes 9

10. Color Measuring
• Color measuring devices
• Distinctions: Light Source
Contents
• Introduction
• Color Measuring
• Spectrophotometers
• Conclusions
© VIGC - 7/09/2009 Practical Evaluation of Spectrophotometers for Color Management Purposes 10

11. Color Measuring
• Color measuring devices
• D50 light (theoretical)
Contents
• Introduction
• Color Measuring
• Spectrophotometers
• Conclusions
© VIGC - 7/09/2009 Practical Evaluation of Spectrophotometers for Color Management Purposes 11

12. Color Measuring
• Color measuring devices
• Gas Filled Tungsten (mostly used)
Contents
• Introduction
• Color Measuring
• Spectrophotometers
• Conclusions
© VIGC - 7/09/2009 Practical Evaluation of Spectrophotometers for Color Management Purposes 12

13. Color Measuring
• Color measuring devices
• White LED (recent)
Contents
• Introduction
• Color Measuring
• Spectrophotometers
• Conclusions
© VIGC - 7/09/2009 Practical Evaluation of Spectrophotometers for Color Management Purposes 13

14. Color Measuring
• Color measuring devices
• Other Distinctions: Scanning Interval
• Reflective measurements: 10nm interval
• Lightsource measurements: 5nm interval
Contents
• Introduction
• Color Measuring
• Spectrophotometers
• Conclusions
© VIGC - 7/09/2009 Practical Evaluation of Spectrophotometers for Color Management Purposes 14

15. Color Measuring
• Color measuring devices
• Scanning Interval: examples
• Reflective measurements: cyan procescolor
• Lightsource measurements: fluorescent light
Contents
• Introduction
• Color Measuring
• Spectrophotometers
• Conclusions
© VIGC - 7/09/2009 Practical Evaluation of Spectrophotometers for Color Management Purposes 15

16. Color Measuring
• Color measuring devices
• Other Distinctions: Bandwidth
• Minimum requirement 400/700 nm
• Best: 340/780 nm
Contents
• Introduction
• Color Measuring
• Spectrophotometers
• Conclusions
© VIGC - 7/09/2009 Practical Evaluation of Spectrophotometers for Color Management Purposes 16

17. Color Measuring
• Color measuring devices
• Other Distinctions: Geometry
• 45°/0° or O°/45° for reflective measurements
Contents
• Introduction
• Color Measuring
• Spectrophotometers
• Conclusions
© VIGC - 7/09/2009 Practical Evaluation of Spectrophotometers for Color Management Purposes 17

18. Color Measuring
• Elements of a color measurement
• Measurement Result
• Spectral power distribution
• CIELAB
• Density
• Tolerance (examples)
• 0.3 ΔE* CIELAB
• 0.15 ΔE CMC(2:1)
• Average DE*94 0.4
• Reliability
Contents
• Do circumstances allow reliable measurements?
• Introduction
• Color Measuring
• Spectrophotometers
• Conclusions
© VIGC - 7/09/2009 Practical Evaluation of Spectrophotometers for Color Management Purposes 18

19. Color Measuring
• Elements of a color measurement
• Reliability
• Example
Contents
• Introduction
• Color Measuring
• Spectrophotometers
• Conclusions
© VIGC - 7/09/2009 Practical Evaluation of Spectrophotometers for Color Management Purposes 19

20. Spectrophotometers

21. Spectrophotometers
• Starting point
• Practical Research
• Performance within the company, not in lab.
• Scope
• 6 different types
• Total of 20 measurement devices
• Test-setup
• Repeatability
• General Accuracy
• Detailed Accuracy
Contents
• Introduction
• Color Measuring
• Spectrophotometers
• Conclusions
© VIGC - 7/09/2009 Practical Evaluation of Spectrophotometers for Color Management Purposes 21

22. Spectrophotometers
• Repeatability
• Can the instrument repeat the measurement
with sufficient accuracy?
• Procedure
• 12 consecutive measurement of a white and blue
patch.
• Same spot (no disposition of the instrument)
• Calculation of the average CIELAB color of the 12
measurement
• Calculation of the average color difference ΔE*ab
Contents of the 12 measurement with the average color
• Introduction
• Color Measuring
• Spectrophotometers
• Conclusions
© VIGC - 7/09/2009 Practical Evaluation of Spectrophotometers for Color Management Purposes 22

23. Spectrophotometers
• Repeatability
• Results (white patch)
Contents
• Introduction
• Color Measuring
• Spectrophotometers
• Conclusions
© VIGC - 7/09/2009 Practical Evaluation of Spectrophotometers for Color Management Purposes 23

24. Spectrophotometers
• Repeatability
• Results (blue patch)
Contents
• Introduction
• Color Measuring
• Spectrophotometers
• Conclusions
© VIGC - 7/09/2009 Practical Evaluation of Spectrophotometers for Color Management Purposes 24

25. Spectrophotometers
• Accuracy (general)
• Can the instrument measure color
accurately?
• Procedure
• measurement of 13 different colors of a
Netprofiler color chart.
• Calculation of the average CIELAB color of the 13
measured colors
• Calculation of the color difference ΔE*ab of the 13
measurement with the reference of the Netprofiler
chart.
Contents
• Averaging of the 13 calculated ΔE*ab-values.
• Introduction
• Color Measuring
• Spectrophotometers
• Conclusions
© VIGC - 7/09/2009 Practical Evaluation of Spectrophotometers for Color Management Purposes 25

26. Spectrophotometers
• Accuracy
• Results
Contents
• Introduction
• Color Measuring
• Spectrophotometers
• Conclusions
© VIGC - 7/09/2009 Practical Evaluation of Spectrophotometers for Color Management Purposes 26

27. Spectrophotometers
• Accuracy (detail)
• Which colors can the instrument measure
accurately?
• Procedure
• measurement of 13 different colors of a
Netprofiler color chart.
• Calculation of the average CIELAB color of the 13
measured colors
• Calculation of the color difference ΔE*ab of the 13
measurement with the reference of the Netprofiler
chart.
Contents
• Introduction
• Color Measuring
• Spectrophotometers
• Conclusions
© VIGC - 7/09/2009 Practical Evaluation of Spectrophotometers for Color Management Purposes 27

28. Spectrophotometers
• Accuracy
• Results
• Average of all instruments
Contents
• Introduction
• Color Measuring
• Spectrophotometers
• Conclusions
© VIGC - 7/09/2009 Practical Evaluation of Spectrophotometers for Color Management Purposes 28

29. Spectrophotometers
• Accuracy
• Results
• According to Instrument type
Contents
• Introduction
• Color Measuring
• Spectrophotometers
• Conclusions
© VIGC - 7/09/2009 Practical Evaluation of Spectrophotometers for Color Management Purposes 29

30. Spectrophotometers
• Accuracy
• Results
• According to Instrument Brand
Contents
• Introduction
• Color Measuring
• Spectrophotometers
• Conclusions
© VIGC - 7/09/2009 Practical Evaluation of Spectrophotometers for Color Management Purposes 30

31. Spectrophotometers
• Accuracy
• Results
• According to Instrument age
Contents
• Introduction
• Color Measuring
• Spectrophotometers
• Conclusions
© VIGC - 7/09/2009 Practical Evaluation of Spectrophotometers for Color Management Purposes 31

32. Spectrophotometers
• Accuracy
• Results
• According to Instrument maintenance
Contents
• Introduction
• Color Measuring
• Spectrophotometers
• Conclusions
© VIGC - 7/09/2009 Practical Evaluation of Spectrophotometers for Color Management Purposes 32

33. Conclusions

34. Conclusions
• Technological evolution
• Search for more suitable light sources is ongoing
• Instrument Type
• Don’r rely on older instrument types for accurate
measurements
• Instrument Brand
• Different brands show different behaviour
• Instrument Maintenance
• Maintenance (white kalibration patch) is very
Contents important.
• Introduction
• Color Measuring • Averaging
• Spectrophotometers • Make use of sufficient averaged measurements to
• Conclusions judge color.
© VIGC - 7/09/2009 Practical Evaluation of Spectrophotometers for Color Management Purposes 34

35. Future Work
• Expansion toward measurement tables
in press rooms
• Example: color accuracy
Contents
• Introduction
• Color Measuring
• Spectrophotometers
• Conclusions
© VIGC - 7/09/2009 Practical Evaluation of Spectrophotometers for Color Management Purposes 35

36. Thanks :-)

37. Titel seminarie
Working together toward greater efficiency

38. Strategic partners VIGC