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Controlling Color in Displays: A discussion on Quality Jean-Baptiste Thomas

Controlling Color in Displays: A discussion on Quality Jean-Baptiste Thomas Centre de Recherche et de Restauration des musées de France CNRS UMR 171. 1. Jean-Baptiste THOMAS, jib.thomas@gmail.com. 09/06/2010. 2. I. Color management. V D65 ( λ ). Acquisition. Reproduction.

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Controlling Color in Displays: A discussion on Quality Jean-Baptiste Thomas

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  1. Controlling Color in Displays: A discussion on Quality Jean-Baptiste Thomas Centre de Recherche et de Restauration des musées de France CNRS UMR 171 1 Jean-Baptiste THOMAS, jib.thomas@gmail.com 09/06/2010

  2. 2 I. Color management VD65(λ) Acquisition Reproduction Transfer via a network, storage, compression, etc. Technology, Model and Quality Direct view Jean-Baptiste THOMAS, jib.thomas@gmail.com 09/06/2010

  3. Color management 3 I. Color management Ds fc VD65(λ) Ds fc COLOR PCS CIEXYZ CIELAB … RGB RGB Jean-Baptiste THOMAS, jib.thomas@gmail.com 09/06/2010

  4. Color management 4 I. Color management Ds fc VD65(λ) Ds fc COLOR PCS CIEXYZ CIELAB … RGB RGB Jean-Baptiste THOMAS, jib.thomas@gmail.com 09/06/2010

  5. Quality 5 II. Displays Jean-Baptiste THOMAS, jib.thomas@gmail.com 09/06/2010

  6. Colorimetric characterization 6 II. Displays • Forward model • CIEXYZ = F(RGB) • CIELAB = F(RGB) • Inverse model • RGB = F-1(CIELAB) RGB CIELAB Jean-Baptiste THOMAS, jib.thomas@gmail.com 09/06/2010

  7. Quality estimation DISPLAY WHITE DISPLAY MEASURE XYZ1 CIELAB1 RGB METRIC XYZ2 MODEL CIELAB2 7 II. Displays Jean-Baptiste THOMAS, jib.thomas@gmail.com 09/06/2010

  8. Quality estimation 8 III. Quality • Metrics • CIELAB colorspace • Quality criterion (colorimetry) • Just noticeable difference: Kang (97), Mahy et al (94) • Quality criterion (Color imaging) • Rules of thumb: Hardeberg (99), Abrardo et al (96) • Perceptabilityacceptance for pictorial images: Stokes et al (92), Catrysse et al (99), Gibson and Fairchild (00) Jean-Baptiste THOMAS, jib.thomas@gmail.com 09/06/2010

  9. Need 9 III. Quality • Professional • THE COLOR RENDERING HAS TO BE PERFECTLY ACCURATE • Consumer • AESTHETIC AND INTENDED MEANING HAVE TO BE PRESERVED Jean-Baptiste THOMAS, jib.thomas@gmail.com 09/06/2010

  10. Need 10 III. Quality I am a good worker, Give me moremoney! Want to ask for more funding ? • CONSUMER: AESTHETIC AND INTENDED MEANING HAVE TO BE PRESERVED Jean-Baptiste THOMAS, jib.thomas@gmail.com 09/06/2010

  11. Need 11 III. Quality I am a good worker, Give me moremoney! Get more work! • CONSUMER: AESTHETIC AND INTENDED MEANING HAVE TO BE PRESERVED Jean-Baptiste THOMAS, jib.thomas@gmail.com 09/06/2010

  12. Need D75 12 III. Quality Color rendering of multi-spectral images of art paintings under different illuminants (Image: C2RMF) • PROFESSIONAL: THE COLOR RENDERING HAS TO BE PERFECTLY ACCURATE Jean-Baptiste THOMAS, jib.thomas@gmail.com 09/06/2010

  13. Set of thresholds 13 III. Quality • Compilation of previousworksadapted to the need • Nothing more than a rule of thumb Jean-Baptiste THOMAS, jib.thomas@gmail.com 09/06/2010

  14. Models classification 14 III. Quality The efficiency of a model is dependent on several factors: the number of measurements, the nature of the data to measure, the computational cost, its accuracy, etc. It depends strongly on the display Jean-Baptiste THOMAS, jib.thomas@gmail.com 09/06/2010

  15. Global quality of a system ? 15 III. Quality Jean-Baptiste THOMAS, jib.thomas@gmail.com 09/06/2010

  16. Global quality of a system ? DISPLAY WHITE RGB1 XYZ1 METRIC XYZ2 RGB2 MODEL-1 CIELAB 16 III. Quality MODEL Evaluation of the model inversion Jean-Baptiste THOMAS, jib.thomas@gmail.com 09/06/2010

  17. Global quality of a system ? DISPLAY WHITE RGB1 DISPLAY MEASURE XYZ1 METRIC XYZ2 RGB2 MODEL-1 CIELAB 17 III. Quality Evaluation of the inverse model Jean-Baptiste THOMAS, jib.thomas@gmail.com 09/06/2010

  18. Global quality of a system ? DISPLAY WHITE XYZ1 CIELAB1 RGB MODEL-1 METRIC CIELAB2 XYZ2 MEASURE DISPLAY 18 III. Quality Perceptual evaluation of the inverse model Jean-Baptiste THOMAS, jib.thomas@gmail.com 09/06/2010

  19. Global quality of a system ? 19 III. Quality Spatial difference in lightness and chroma Jean-Baptiste THOMAS, jib.thomas@gmail.com 09/06/2010

  20. Global quality of a system ? 20 III. Quality A illumination D65 illumination Gamut mapping Colors out of gamut Jean-Baptiste THOMAS, jib.thomas@gmail.com 09/06/2010

  21. Global quality of a system ? 21 III. Quality Jean-Baptiste THOMAS, jib.thomas@gmail.com 09/06/2010

  22. Global quality of a system ? 22 III. Quality • NO INFORMATION ON ACTUAL QUALITY Jean-Baptiste THOMAS, jib.thomas@gmail.com 09/06/2010

  23. So what? 23 IV. This is almost the end • Requiredaccuracydepends on the need • No opposition withconstraints • Model quality ≠ Color reproduction quality • Depending on purpose • Spatial issue • Colorimetry and color management are point wise • Psycho-physicalevaluationisdifficult and expensive Jean-Baptiste THOMAS, jib.thomas@gmail.com 09/06/2010

  24. The worst thing 24 IV. This is almost the end IT IS IMAGE DEPENDENT Jean-Baptiste THOMAS, jib.thomas@gmail.com 09/06/2010

  25. 25 IV. This is the end, beautiful friend CHOOSE WHAT YOU WANT TO BE: • Be silly: Try to find a solution • Be pragmatic: Pretend it is OK like this • Be wise: Change research interest • Be lazy: Go to fish Jean-Baptiste THOMAS, jib.thomas@gmail.com 09/06/2010

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