Cheng Li Supervisor : Prof. M. Ronnier Luo

1. Colour and Imaging Group Department of Colour Science Evaluation of Visual Colour Fidelity Cheng Li Supervisor : Prof. M. Ronnier Luo

2. Aim • A reliable experimental method for evaluating the colour rendering property between test and reference illuminants • Focus on ‘colour fidelity’

3. Light Sources

4. 15 Test Samples

5. Viewing Cabinets • 9 observers and each repeated twice

6. Experimental Procedure Task: To scale the visual colour difference of test samples viewed under one of the test simulators and then under thereference lamp • Steps: • Observers were first asked to adapt to the test source for 15 seconds and remember the colour of a randomly selected sample; • Observers were adapted under the reference lamp for another 15 seconds; • After re-adaptation under the reference source, the test sample was shown again, and the observers were asked to estimate the colour difference between the colour seen under the reference lamp and that memorised colour by using the grey scale method • Note:If observers could not memorise the colour previously seen under the test simulator, they were allowed to see the test sample again, but 15 seconds adaptation time under both test source and reference lamp had to be applied.

7. Results

8. Effect of colour difference equations CV values for different colour difference calculation methods for each simulator

9. Results CV values for different colour difference calculation methods for all simulators

10. r=0.8641 r=0.9203 Results: Less scatter for CAM02-UCS than current CRI

11. CRI-CAM02UCS CRI-CAM02UCS Colour differences of 14 reflective samples are calculated in the CAM02-UCS uniform colour space The CRI-CAM02UCS is re-scaled to keep consistence with the original CIE CRI

12. CRI-CAM02UCS

13. Colour and Imaging Group Department of Colour Science Thank you