controlling color in displays: a discussion on quality jean-baptiste thomas
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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, [email protected]. 09/06/2010. 2. I. Color management. V D65 ( λ ). Acquisition. Reproduction. - PowerPoint PPT PresentationTRANSCRIPT
Controlling Color in Displays:A discussion on Quality
Jean-Baptiste Thomas
Centre de Recherche et de Restauration des musées de France CNRS UMR 171
Jean-Baptiste THOMAS, [email protected] 09/06/2010
1
VD65(λ)
Acquisition Reproduction
Technology,Modeland
Quality
Direct view
Transfer via a network, storage, compression, etc.
I. Color management
Jean-Baptiste THOMAS, [email protected]
2
09/06/2010
I. Color management
Jean-Baptiste THOMAS, [email protected]
Ds
fc
D s fc
VD65(λ)
COLORPCS
CIEXYZCIELAB
…
RGBRGB
3
Color management
09/06/2010
I. Color management
Jean-Baptiste THOMAS, [email protected]
Ds
fc
D s fc
VD65(λ)
COLORPCS
CIEXYZCIELAB
…
RGBRGB
4
Color management
09/06/2010
Technology
Gamut mappingModel
II. Displays
Jean-Baptiste THOMAS, [email protected]
5
Quality
09/06/2010
II. Displays
Jean-Baptiste THOMAS, [email protected]
6
Colorimetric characterization
RGB CIELAB
Forward modelCIEXYZ = F(RGB)CIELAB = F(RGB)
Inverse modelRGB = F-1(CIELAB)
09/06/2010
II. Displays
Jean-Baptiste THOMAS, [email protected]
7
Quality estimation
CIELAB1DISPLAY
MODEL
MEASURE
RGB
DISPLAY WHITE
XYZ1
CIELAB2
METRIC
XYZ2
09/06/2010
III. Quality
Jean-Baptiste THOMAS, [email protected]
8
Quality estimation
• Metricso CIELAB color space
• Quality criterion (colorimetry)o Just noticeable difference: Kang (97), Mahy et al (94)
• Quality criterion (Color imaging)o Rules of thumb: Hardeberg (99), Abrardo et al (96)o Perceptability acceptance for pictorial images: Stokes et al
(92), Catrysse et al (99), Gibson and Fairchild (00)
09/06/2010
III. Quality
Jean-Baptiste THOMAS, [email protected]
9
Need
• Professionalo THE COLOR RENDERING HAS TO BE PERFECTLY ACCURATE
• Consumero AESTHETIC AND INTENDED MEANING HAVE TO BE PRESERVED
09/06/2010
III. Quality
Jean-Baptiste THOMAS, [email protected]
10
Need
Want to ask for more funding ?
I am a good worker,
Give me more money!
CONSUMER: AESTHETIC AND INTENDED MEANING HAVE TO BE PRESERVED
09/06/2010
III. Quality
Jean-Baptiste THOMAS, [email protected]
11
Need
Get more work!
I am a good worker,
Give me more money!
CONSUMER: AESTHETIC AND INTENDED MEANING HAVE TO BE PRESERVED
09/06/2010
III. Quality
Jean-Baptiste THOMAS, [email protected]
12
Need
PROFESSIONAL: THE COLOR RENDERING HAS TO BE PERFECTLY ACCURATE
Color rendering of multi-spectral imagesof art paintings under different illuminants
(Image: C2RMF)
09/06/2010
III. Quality
Jean-Baptiste THOMAS, [email protected]
13
Set of thresholds
• Compilation of previous works adapted to the need• Nothing more than a rule of thumb
09/06/2010
III. Quality
Jean-Baptiste THOMAS, [email protected]
14
Models classification
PLVC Bala PLCC* Polyharmonic splines
GOGO
54 (XYZ) measures
1 to 3 visual tasks times
1 to 3 pictures
54 (Y) measures3 (XYZ)
216 (XYZ) measures
4 to 54 (Y) measures3 (XYZ)
Technology dependent
Technology dependent
Technology dependent
Technology independent
CRT
Professional or Consumer
Consumer Professional or Consumer
Professional Consumer
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
09/06/2010
III. Quality
Jean-Baptiste THOMAS, [email protected]
15
Global quality of a system ?
Technology: spatial, temporal
Gamut mappingInverse model
09/06/2010
Jean-Baptiste THOMAS, [email protected]
16
MODEL-1 CIELAB
RGB1
DISPLAY WHITE
XYZ1
METRIC
XYZ2RGB2
Evaluation of the model inversion
Global quality of a system ?
09/06/2010
MODEL
III. Quality
Jean-Baptiste THOMAS, [email protected]
17
MODEL-1 CIELAB
DISPLAY MEASURERGB1
DISPLAY WHITE
XYZ1
METRIC
XYZ2RGB2
Evaluation of the inverse model
Global quality of a system ?
09/06/2010
III. Quality
Jean-Baptiste THOMAS, [email protected]
18
MODEL-1CIELAB1
DISPLAYMEASURE
RGB
DISPLAY WHITE
XYZ1
CIELAB2
METRIC
XYZ2
Perceptual evaluation of the inverse model
Global quality of a system ?
09/06/2010
III. Quality
III. Quality
Jean-Baptiste THOMAS, [email protected]
19
Spatial difference in lightness and chroma
Global quality of a system ?
09/06/2010
III. Quality
Jean-Baptiste THOMAS, [email protected]
20
A illumination D65 illumination
Colors out of gamut
Global quality of a system ?
Gamut mapping
09/06/2010
III. Quality
Jean-Baptiste THOMAS, [email protected]
21
Global quality of a system ?
Technology: spatial, temporal
Gamut mappingInverse model
09/06/2010
III. Quality
Jean-Baptiste THOMAS, [email protected]
22
Global quality of a system ?
NO INFORMATION ON ACTUAL QUALITY
09/06/2010
IV. This is almost the end
Jean-Baptiste THOMAS, [email protected]
23
So what?
• Required accuracy depends on the needo No opposition with constraints
• Model quality ≠ Color reproduction qualityo Depending on purpose
• Spatial issueo Colorimetry and color management are point wise
• Psycho-physical evaluation is difficult and expensive
09/06/2010
IV. This is almost the end
Jean-Baptiste THOMAS, [email protected]
24
The worst thing
IT IS IMAGE DEPENDENT
09/06/2010
IV. This is the end, beautiful friend
Jean-Baptiste THOMAS, [email protected]
25
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
09/06/2010