Colorimetric characterization of (historic) coverings based on the

Colorimetric characterization of (historic) coverings based on the

5th International Congress on: “Science and technology for the Safeguard of Cultural Heritage in the
Mediterranean Basin”, 22nd– 25th November 2011, Istanbul, Turkey
Colorimetric characterization of
(historic) coverings based on the
hyperspectral method
PEDRO PROVIDÊNCIA (1), LUÍS FREIRE (1,3),
FRANCISCO BRARDO (2), LÍDIA CATARINO (1), JOSÉ AGUIAR (4), PAULO
FIADEIRO (2), FRANCISCO GIL (1)
(1) Faculty of Science and Technology, University of Coimbra (FCTUC), PORTUGAL,
[email protected]
(2) University of Beira Interior, Covilhã (UBI), PORTUGAL
(3) Nautic School of Infante D.Henrique, Paço d’Arcos, Lisbon (ENIDH), PORTUGAL
(4) Faculty of Architecture, Technical University of Lisbon (FAUTL), PORTUGAL
PTDC/AUR-URB/113635/2009 - FCOMP-01-0124-FEDER014163
View of Coimbra; oil on canvas; António Gonçalves Neves/1865
Coimbra, charm city; Artur Loureiro/1907; oil on canvas
‘Serrana’ Boats on Mondego;
António Victorino/c. 1940/1950
Tri-chromatic systems
• Metamerism
(where colour has a spectral
dependence of the illuminant)
and
spatial
• Impossible to obtain device independent colour
(where the spectral sensitivity of the device differ
from spectral sensitivity of the human eye)
Colorimetric reproduction is adjusted by visual
comparison with the original
Spectral systems
Image acquisition system with more
spectral bands
R(λ) = re(λ)
S(λ)
S(λ) represents the spectral power
distribution of the light source, re(λ) the
spectral reflectance of an object surface
point and R(λ) the radiance of the
reflected light from that surface point
(colour physical signal)
re(λ)
S(λ)
R(λ) = re(λ) S(λ)
Thank you