Accuracy of srgb colour reproduction through a camera and a lcd imaging display
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Accuracy of sRGB colour reproduction through a camera and a LCD imaging display. Kyung Hoon, OH* Sophie , Triantaphillidou [email protected] 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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Accuracy of sRGB colour reproduction through a camera and a LCD imaging display

Kyung Hoon, OH*

Sophie, Triantaphillidou

[email protected]

Imaging Technology Research Group,

University of Westminster

http://www.wmin.ac.uk/mad/page-1626


Contents

  • Overview of the Projects (Introduction)

  • Experiments (Equipments, Procedure)

  • Conclusion


Introduction


Introduction


Introduction

Characterization

Characterization 1

I.C.S: Independent Colour space

I.C.S

Characterization

Characterization2

.

.

.

.

.

.

.

.

.

.

.

.

Characterization

Characterizationn


Introduction

Reference (2)


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


Introduction

1.Reference display

2. Reference observer

3. Viewing condition

.

.

.

sRGB

Encoding Transformation


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


sRGB Inverse Encoding transformation

Introduction

Step 2:


Introduction

1.Reference display

2. Reference observer

3. Viewing condition

.

.

.

sRGB

Encoding Transformation


Introduction

?

1.Reference display

2. Reference observer

3. Viewing condition

.

.

.

sRGB

Encoding Transformation


Question

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


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


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


Experimental procedure

  • 1. The accuracy of SRGB encoding transformation

Inverse encoding Transformation

encoding Transformation

Calculated

XYZ

Measured

XYZ

sRGB

ΔE


Experimental Result

1. The accuracy of sRGB encoding transformation

C.C.C: Macbeth ColorChecker chart


Experimental Result

1. The accuracy of sRGB encoding transformation

Macbeth ColorChecker chart

Kodak Q-60


Experimental procedure

  • 2. The accuracy of SRGB colours of a digital camera

Inverse encoding Transformation

Calculated

XYZ

Measured

XYZ

Camera

sRGB

ΔE


Setup for Image Capture

  • 2. The accuracy of SRGB colours of a digital camera


Experimental Result

2. The accuracy of sRGB colours of a digital camera

C.C.C: Macbeth ColorChecker chart


Experimental procedure

  • 3. The accuracy of SRGB colours characterization in LCD

Inverse encoding Transformation

Measured

XYZ

Calculated

XYZ

LCD

RGB

ΔE


Setup for Image Capture

  • 3. The accuracy of SRGB colours characterization in LCD

h/5

h/5

h=Image height


Experimental Result

3. The accuracy of sRGB displayed colours


Experimental Result

3. The accuracy of sRGB displayed colours


Experimental procedure

  • 4. The accuracy of SRGB colours through whole system

    (Camera-LCD).

Measured

XYZ

Measured

XYZ

Camera

LCD

sRGB

ΔE


Experimental Result

4. The accuracy of sRGB whole system

C.C.C: Macbeth ColorChecker chart


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.


Furtherwork

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


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.


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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