Main research interest at our Color Imaging Lab (April, 2010)

1. Colour Imaging Lab
www.ugr.es/local/colorimg
Departamento de Óptica, Facultad de Ciencias,
Universidad de Granada, 18071-Granada (SPAIN)
Research interests, 9th April 2010

2. Colour Imaging Lab
Universidad de Granada
www.ugr.es/~colorimg
Permanent staff:
Javier Romero Juan Luis Javier Eva M. Valero
Nieves Hernández-Andrés
Ph.D. students
Clara Plata Raul Luzón Juan Ojeda

3. Colour Imaging Lab
Universidad de Granada
www.ugr.es/~colorimg
Colour vision Colour images
Colour
discrimination Reflectances Illuminants Imaging devices
Chromatic Identification and Color and spectral Calibration
frequencies - SMSF reconstruction characterization
Chromatic contrast Multispectral Objects under Noise estimation
sensitivity images natural light
3D objects Optimal sensors
Colour constancy Artificial illuminants
Spectral estimation
Temporal changes
algorithms
Color invariants Multispectral
Optics correlation imaging
Atmospheric optics
Colour and Spectral Imaging
Education in optics

4. Spectral information recovery from RGB
responses
● Multispectral image capture
problem
+
● Our approach: camera digital counts calculation (simulated
RGB data, with or without added color filters)
700
ri =
λ
∑ S (λ )T (λ )Q (λ )
= 400
i

5. Color constancy and illuminant estimation
Recovering spectral information about objects and illuminants
simultaneously with an RGB camera.
Spectral-imaging learning-based algorithm that directly relates
camera sensor outputs and illuminant spectra. 6
4
x 10
5 GFC= 0.9771
RMSE= 0.0274
4 Color diff.= 1.5
AE= 12.2
3
2
1
0
0 5 10 15 20 25
RGB error
0.35
0.3
0.25
Relative units
0.2
0.15
0.1
0.05
0
400 450 500 550 600 650 700
Wavelength (nm)

6. RGB cameras to recover normals, albedo
and spectral information
Reflected light from objects depends on reflectance (albedo) and
illumination…
… and on surface relief.

7. RGB cameras to recover normals, albedo
and spectral information
Spectral image acquisition + Photometric- stereo
0.5
0.45
0.4
0.35
0.3
0.25
0.2
400 450 500 550
Wavelenght (nm)
600 650 700
N
•Image rendering

8. Natural illumination
Daylight and skylight spectra have complex and spiky spectral
profiles, with spatially and temporally variable absorption bands.
0.3
0.2
daylig
Low dimension 0.1
ht
representation 0
-0 . 1
models: PCA, -0 . 2
ICA, NNMF, … -0 . 3
V1
V2
V3
V4
V5
-0 . 4
380 400 450 50 0 5 50 600 650 700 7 50 78 0
lo n g d e on d a (n m )

9. Multispectral system for skylight illumination
Multispectral system: Skylight spectral information at each
pixel of the image
Skylight spectra: most basic feature in atmospheric optics: to
be used for estimating, for example, the Aerosol Optical Depth
(AOD), the Angström Alpha parameter (α) and the Cloud
Optical Depth (COD).
0.030
spectral radiance (W/m nmstr)
0.025
2
0.020
0.015
0.010
0.005
0.000
400 500 600 700
wavelength (nm)

10. Illuminant invariants
Color-invariant descriptors:
Analysis of illuminant invariants in color imaging.

11. Colour Imaging Lab
Universidad de Granada
www.ugr.es/~colorimg
Since 2001, we published...
International ISI journal papers: 31
• Journal of the Optical Society of America A
• Applied Optics
• Vision Research
• Color Research and Applications
• Journal of the Imaging Science and Technology
• American Journal of Physics
• Optical Review
• Displays
• J. Math. Imaging and Vision
• PNAS (Proceedings of the National Academy of Sciences)
Proceedings in International meetings: 34
I+D+I Proyects and contracts: 7
4 from the Spanish Ministry of Science and Innovation
1 from the Junta de Andalucía Excellence projects
2 from private companies (Robotiker-Tecnalia; Chromasens)

12. Colour Imaging Lab
Universidad de Granada
www.ugr.es/~colorimg
International Conferences
10th Congress of the International Colour Association (AIC’05)
419 papers (208 oral + 211 posters) and 538
participants, 36 sessions, 24 invited speakers
Colour vision and ageing, Applied colorimetry, Colour physics, Colour vision,
Colour vision with natural images, Colour education, Multispectral colour
science, Environmental colour design, Photoreceptors and colour vision
mechanisms, Colour appearance, Colour emotion, Camera and displays
characterization, Evaluation of image quality, Colour preference, Gamut
mapping, Computational colour constancy, Colour in architecture, Art and
colour, Colour in computer vision, Colour, culture and design, Colour
differences

13. Colour Imaging Lab
Universidad de Granada
www.ugr.es/~colorimg
Instruments:
Liquid Cristal Tunable Filters: VariSpec VIS from CRi (400-720 nm)
Narrow band filters and wide band filters
Monochrome cameras: Retiga SRV 1394 cooled.
RGB cameras: Retiga Q1300C
Retiga EXI Fast cooled
ProgRes C14 cooled

14. Colour Imaging Lab
Universidad de Granada
www.ugr.es/~colorimg
Instruments:
Scanner 3 D (del Centro de Instrumentación Científica)
Hyperspectral Imaging based on Volume Bragg Gratings
(PhotonEtc, 400-1000 nm, FOV: 15°x6°)
Color samples: Color Checker, Color Checker DC,
Munsell, NCS, muestras propias con textura y otros.

15. Colour Imaging Lab
Universidad de Granada
www.ugr.es/~colorimg
Instruments:
Spectroradiometers:
• SpectraScan PR650 Photoresearch (380-780 nm)
• LI-COR 1800 (300-1100 nm)
• GER-2600 from SpectraVista (350-2500 nm)
• AvaSpec 2048 SPU from Avantes (360-860 nm)
Other instruments (goniocolorimeters, spectrophotometers, ...)

16. Colour Imaging Lab
Universidad de Granada
www.ugr.es/~colorimg
...Teaching activities:
Primera ventana a la Ciencia “Lo que el ojo no ve” en la 4ª fase del
Parque de las Ciencias.
Desde Noviembre de 2008 a Agosto de 2009
Optics and Photonics News, May 2009

18. Summer internships 2009
Natalia Lybova Yu Hu (China)
(Rusia)
Sweet Khisa
(Bangladesh)

19. Master thesis students in Granada
January-June 2010
Yu Hu (China)
With MULTISCAN
Pierre-Alexandre Jay
(France)
Talha Ahmed (Pakistan)

20. The EMJD VISOR (Erasmus Mundus Joint Doctorate
in VISion, Optics and Robotics)
GUC
GUC
HW
HW UJO
UJO
UdG
UdG
UJM
UJM
UGR
UGR
UB
UB
To foster the excellence in theoretical and applied
research in the field computer vision, optics, colour
science and robotics.

21. The EMJD VISOR (Erasmus Mundus Joint Doctorate
in VISion, Optics and Robotics)