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Accuracy of sRGB colour reproduction through a camera and a LCD imaging display

Accuracy of sRGB colour reproduction through a camera and a LCD imaging display. Kyung Hoon, OH* Sophie , Triantaphillidou *H.oh2@wmin.ac.uk. I maging T echnology R esearch G roup, University of Westminster http://www.wmin.ac.uk/mad/page-1626. Contents.

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Accuracy of sRGB colour reproduction through a camera and a LCD imaging display

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  1. Accuracy of sRGB colour reproduction through a camera and a LCD imaging display Kyung Hoon, OH* Sophie, Triantaphillidou *H.oh2@wmin.ac.uk Imaging Technology Research Group, University of Westminster http://www.wmin.ac.uk/mad/page-1626

  2. Contents • Overview of the Projects (Introduction) • Experiments (Equipments, Procedure) • Conclusion

  3. Introduction

  4. Introduction

  5. Introduction Characterization Characterization 1 I.C.S: Independent Colour space I.C.S Characterization Characterization2 . . . . . . . . . . . . Characterization Characterizationn

  6. Introduction Reference (2)

  7. Introduction I.C.S Characterization Characterization • Characterization methods • 1. Custom Profile: Polynominal regression methods, GOG model etc • 2. Generic Profile: Profile supplied manufacture • 3. Prcoess profile: sRGB model, SWOP

  8. Introduction 1.Reference display 2. Reference observer 3. Viewing condition . . . sRGB Encoding Transformation

  9. sRGB Inverse Encoding transformation Introduction Step 1: BDC is a black digital count and a white digital count is WDC (8-bits/channel) if R’sRGBG’sRGBB’sRGB≤0.04045 or if R’sRGBG’sRGBB’sRGB 〉0.04045

  10. sRGB Inverse Encoding transformation Introduction Step 2:

  11. Introduction 1.Reference display 2. Reference observer 3. Viewing condition . . . sRGB Encoding Transformation

  12. Introduction ? 1.Reference display 2. Reference observer 3. Viewing condition . . . sRGB Encoding Transformation

  13. Question Is there correct colour reproduction via sRGB encoding transformation in a camera and a LCD imaging display ?

  14. Introduction • The accuracy of SRGB encoding transformation • The accuracy of sRGB colours of a digital camera • The accuracy of sRGB LCD displayed colours • The accuracy of sRGB whole system

  15. Equipment Used • Two Test targets : a Macbeth ColorChecker chart & Kodak Q-60 • Camera: a full-frame (36×24mm) Cannon-1Ds with a 28-135mm zoom lens • LCD : A 21 inch EIZO CG210 LCD • Measuring instruments: X-Rite spectrophotometer for Kodak Q-60 Color-Eye 7000A spectrophotometer for C.C.C Minolta CS-200 colorimeter for LCD C.C.C: Macbeth ColorChecker chart

  16. Experimental procedure • 1. The accuracy of SRGB encoding transformation Inverse encoding Transformation encoding Transformation Calculated XYZ Measured XYZ sRGB ΔE

  17. Experimental Result 1. The accuracy of sRGB encoding transformation C.C.C: Macbeth ColorChecker chart

  18. Experimental Result 1. The accuracy of sRGB encoding transformation Macbeth ColorChecker chart Kodak Q-60

  19. Experimental procedure • 2. The accuracy of SRGB colours of a digital camera Inverse encoding Transformation Calculated XYZ Measured XYZ Camera sRGB ΔE

  20. Setup for Image Capture • 2. The accuracy of SRGB colours of a digital camera

  21. Experimental Result 2. The accuracy of sRGB colours of a digital camera C.C.C: Macbeth ColorChecker chart

  22. Experimental procedure • 3. The accuracy of SRGB colours characterization in LCD Inverse encoding Transformation Measured XYZ Calculated XYZ LCD RGB ΔE

  23. Setup for Image Capture • 3. The accuracy of SRGB colours characterization in LCD h/5 h/5 h=Image height

  24. Experimental Result 3. The accuracy of sRGB displayed colours

  25. Experimental Result 3. The accuracy of sRGB displayed colours

  26. Experimental procedure • 4. The accuracy of SRGB colours through whole system (Camera-LCD). Measured XYZ Measured XYZ Camera LCD sRGB ΔE

  27. Experimental Result 4. The accuracy of sRGB whole system C.C.C: Macbeth ColorChecker chart

  28. Conclusion • 1. In sRGB encoding transformation, the out of gamut colours are clipped. • 2. The digital camera reproduces sRGB colour incorrectly. • 3. The LCD shows good sRGB accuracy. • 4. The sRGB colours via a camera and a LCD are quite inaccurate, because of the inaccuracte performance of a digital camera.

  29. Furtherwork • The digital camera’s characterization and further calibration of the digital image files.

  30. References 1. EN:61966-2-1.Multimedia systems and equipment-colour measurment and management-part 2-1: colour management-Defalut RGB colour space- sRGB. European standard : IEC, 2000. ISBN 0 580 36416 X. 2. Sharma, Abhay. Introduction. Understanding color management. Clifton Park, NY : Thomson/Delmar Learning, 2004, 1, pp. 1-48. 3. Pointer, M R, Attridge, G G and Jacobson, R E. Practical camera characterization for colour measurement. The Imaging science Journal. 2001, Vol. 43, pp. 63-80. 4. Cannon.EOS-1Ds Digital Instruction Manual. Tokyo : Cannon, 2002. 5. [Online] EIZO. http://www.eizo.com/products/graphics/cg210-n/spec.asp.

  31. References 6. [Online] gretagmacbeth. http://www.gretagmacbeth.com/index/products/products_colorcheckers/products_cc-overview/products_colorchecker.htm. 7. [Online] Kodak. http://www.kodak.com/global/en/professional/products/films/catalog/kodakProfessionalQ60Targets.jhtml?id=0.2.22.14.13.24.3&lc=en. 8. Orava, J and Jaaskelainen, T. Color Errors of Digital camera. Color reseearch and application. Jun 2004, Vol. 29, 3, pp. 217-221. 9. Kang, Henry R. RGB color space . Computational color technology. Bellingham : SPIE Press, 2006, 6, pp. 77-101.

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