Departamento de Departamento de ÓÓptica, Facultad de Ciencias, ptica, Facultad de Ciencias, Universidad de Granada, 18071Universidad de Granada, 18071--Granada (SPAIN)Granada (SPAIN)
Colour Imaging Lab
www.ugr.es/local/colorimg
Research interests, 9th April 2010
Colour Imaging LabUniversidad de Granada
www.ugr.es/~colorimg
Javier Romero Eva M. Valero
Clara Plata
Javier
Hernández-Andrés
Permanent staff:
Ph.D. students
Raul Luzón
Juan Luis
Nieves
Juan Ojeda
Chromatic
frequencies - SMSF
Colour
discrimination
Chromatic contrast
sensitivity
Colour vision
Optics correlation
Education in optics
Colour Imaging LabUniversidad de Granada
www.ugr.es/~colorimg
Colour constancy
Color and spectral
characterization
Temporal changes
Artificial illuminants
Color invariants
Objects under
natural light
IlluminantsReflectances
Colour images
Multispectral
images
Identification and
reconstruction
3D objects Optimal sensors
Atmospheric optics
Imaging devices
Calibration
Noise estimation
Multispectral
imaging
Spectral estimation
algorithms
Colour and Spectral Imaging
Spectral information recovery from RGB responses
● Our approach: camera digital counts calculation (simulated
RGB data, with or without added color filters)
700
400
( ) ( ) ( )i ir S T Q
λλ λ λ
=
= ∑
+
● Multispectral image capture
problem
� 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.
Color constancy and illuminant estimation
0 5 10 15 20 250
1
2
3
4
5
6x 10
4
RGB error
GFC= 0.9771RMSE= 0.0274Color diff.= 1.5AE= 12.2
400 450 500 550 600 650 7000
0.05
0.1
0.15
0.2
0.25
0.3
0.35
Wavelength (nm)R
elat
ive
units
… and on surface relief.
Reflected light from objects depends on reflectance (albedo) and
illumination…
RGB cameras to recover normals, albedoand spectral information
Spectral image acquisition Photometric- stereo+
400 450 500 550 600 650 700
0.2
0.25
0.3
0.35
0.4
0.45
0.5
Wavelenght (nm) N
RGB cameras to recover normals, albedoand spectral information
•Image rendering
Natural illumination
380 400 450 500 550 600 650 700 750 780-0.4
-0.3
-0.2
-0.1
0
0.1
0.2
0.3
long de onda (nm )
V 1V 2V 3V 4V 5
daylight
Daylight and skylight spectra have complex and spiky spectral
profiles, with spatially and temporally variable absorption bands.
Low dimension
representation
models: PCA,
ICA, NNMF, …
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).
400 500 600 7000.000
0.005
0.010
0.015
0.020
0.025
0.030
spec
tral
rad
ianc
e (W
/m2 nm
str)
wavelength (nm)
Illuminant invariants
�Color-invariant descriptors:
Analysis of illuminant invariants in color imaging.
Colour Imaging LabUniversidad 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)
Colour Imaging LabUniversidad 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
Colour Imaging LabUniversidad 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
Colour Imaging LabUniversidad 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.
Colour Imaging LabUniversidad 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, ...)
Colour Imaging LabUniversidad 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
Yu Hu (China)
Summer internships 2009
Natalia Lybova(Rusia)
Sweet Khisa(Bangladesh)
Pierre-Alexandre Jay (France)
Yu Hu (China)With MULTISCAN
Talha Ahmed (Pakistan)
Master thesis students in Granada
January-June 2010
The EMJD VISOR (Erasmus Mundus Joint Doctorate in VISion, Optics and Robotics)
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HWHW
UGRUGR
UBUB
UJMUJM
GUCGUC
UJOUJO
� To foster the excellence in theoretical and applied research in the field computer vision, optics, colour
science and robotics.
The EMJD VISOR (Erasmus Mundus Joint Doctorate in VISion, Optics and Robotics)
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