Working PaperPDF Available

Natural color representation of Sentinel-2 data

x y
z
f
f
f?= arg min
f:
1
|S| X
a∈S
kf(S2(a)) XYZ(a)k2
2,
S
S2(a)
aXYZ(a)a
Full spectra
Sentinel-2 responses
CIE XYZ responses
MSI
CIE XYZ
f
f?T
(X, Y, Z) = T·S(a)S(a)
a
f?
ρ1, ρ2, . . . , ρmm
E65 a1, a2, . . . , am
ai=E65 ·ρia
ˆ
Bj(a) := 1
ksjkZ
0
sj(λ)a(λ)
j
a sjj
X(a) := 1
NZ
0
a(λ)x(λ)dλ,
Y(a) := 1
NZ
0
a(λ)y(λ)dλ,
Z(a) := 1
NZ
0
a(λ)z(λ)dλ,
N:= Z
0
E(λ)y(λ)dλ,
X Y Z
a a =E·ρiE ρi
m a1, a2, . . . , am
C·α=r13 m C
Cj,i =ˆ
Bj(ai)r ri=X(ai)
O(b2(m+b))
b m
p q T
w h O(whpq)
T
(B1, B2, B 3, B4) (X, Y, Z )
T=
0.362 0.323 0.609 0.357
0.094 0.082 0.659 0.166
0.892 0.129 0.033 0.012
.
B2B3B4T(B2, B3, B 4)
(X, Y, Z)
T=
0.268 0.362 0.371
0.240 0.587 0.174
1.463 0.427 0.043
.
= = =
T=
0.180 0.358 0.412
0.072 0.715 0.213
0.950 0.119 0.019
.
a
a(λ) = ρ(λ)E(λ)ρ
E
a:R0R0a=E·ρ
N f1, f2, . . . , fN:R0[0,1] ρ=
α1f1+. . . +αNfNα1, . . . , αNR
a j
ˆ
Bj(a) = 1
ksjkZ
0
sj(λ)a(λ)
=1
ksjkZ
0
sj(λ) N
X
i=1
αiE(λ)fi(λ)!
=
N
X
i=1
αi
1
ksjkZ
0
sj(λ)E(λ)fi(λ)
=
N
X
i=1
αiAi,j ,
N13 A Ai,j := ˆ
Bj(E·fi)
ˆ
BjA
a S(a)=(ˆ
B1(a),..., ˆ
B13(a)) = α = (α1, α2, . . . , αN)
a
(X, Y, Z)T=D·α=D·A1·S(a),
A
DRN×3Di,1:= X(fi)Di,2:= Y(fi)
Di,3:= Z(fi)X Y Z
A1
A N
N= 4
T=DA1
=
0.141 0.019 0.544 0.325
0.016 0.247 0.629 0.154
0.714 0.315 0.03 0.002
.
(R, G, B) = M·(X, Y, Z ),
M
(rsRGB, gsRGB , bsRGB) = (χ(R), χ(G), χ(B)),
χ:RR
χ(C) =
255 ·12.92 ·C, C 0.0031308;
255 ·(1.055 ·C1/2.40.055), .
a
(r0, g0, b0) = χ(M·T·S(a)),
χ
M
χ
2.2
L L := Lγ
a b
Sentinel-2 XYZ LAB
LABXYZ
sRGBlin
sRGB8bit
T
M
γ-adjust L
χ
c1:= (L?
1, a?
1, b?
1)
c2:= (L?
2, a?
2, b?
2)
E?
a,b(c1, c2) := q(L?
2L?
1)2+ (a?
2a?
1)2+ (b?
2b?
1)2.
2.3
E?
a,b(αc1, αc2) =
αE?
a,b(c1, c2)
DN
S2
DN sRGB8bit
DN S2 XYZ sRGB
lin sRGB8bit
DN S2 XYZ LABXYZ sRGBlin sRGB8bit
DN S2 XYZ sRGBlin sRGB8bit
DN S2 XYZ sRGB
lin
I
sRGB8bit
DN S2 XYZ sRGB
lin sRGB8bit
DN S2 XYZ LABXYZ sRGBlin sRGB8bit
DN S2 XYZ sRGBlin sRGB8bit
DN S2 XYZ sRGB
lin sRGB8bit
DN S2 XYZ LABXYZ sRGBlin sRGB8bit
DN S2 XYZ sRGBlin sRGB8bit
DN S2 XYZ sRGB
lin sRGB8bit
DN S2 XYZ LABXYZ sRGBlin sRGB8bit
DN S2 XYZ sRGBlin sRGB8bit
4
T
7.96113.00
19.5748.63
45.5012.20
35.05120.00
40.670.58
38.5427.08
45.5012.20
40.670.58
T
35.05◦ ◦
T
T
Article
Full-text available
Utilizarea indicilor spectrali de vegetatie (NDVI) din imaginile satelitare pentru delimitarea zonelor de managemente ale culturilor agricole anuale Raport de cercetare Student: Vintileanu Alin-Nicolae Abstract: Utilizarea Indicelui de Vegetație cu Diferență Normalizată (NDVI) obținut din imaginile satelitare poate îmbunătăți procesul de delimitare a zonelor de management (MZ) pentru culturile anuale, reflectându-se în beneficiile socio-economice și ale mediului înconjurător. Scopul acestui studiu este acela de a compara zone de management delimitate din punct de vedere al fertilității solului pe baza datelor obținute din culturile anuale folosind indicele NDVI obținut din imaginile satelitare. Stiudul este realizat în trei zone localizate în Câmpia Română, mai precis în Câmpia Bărăganului, România. Zonele de management au fost delimitate folosind algoritmul fuzzy c-means. În urma studiului, zonele de management bazate pe calculul NDVI-ului din imaginile satelitare corelat cu datele de productivitate, sugerează că NDVI-ul poate înlocui sau poate fi complementar pentru datele de productivitate în scopul delimitării zonelor de management pentru cunoașterea sistemelor necesare culturilor anuale. Cuvinte cheie: fuzzy c-means, imagini satelitare, indice de vegetație, zonă de management
Article
The new Sentinel-2 Multi Spectral Imager instrument has a set of bands with very similar spectral windows to the main bands of the Landsat Thematic Mapper family of instruments. While these should, in principle, give broadly comparable measurements, any differences are a function not only of the differences in the sensor responses, but also of the spectral characteristics of the target pixels. In order to test for and quantify differences between these sensors, a large set of coincident imagery was assembled for the Australian landscape. Comparisons were carried out in terms of surface reflectance, and also in terms of biophysical quantities estimated from the reflectances. Small but consistent differences were found, and suitable adjustment equations fitted to enable transformation of Sentinel-2A reflectance values to more closely match Landsat-7 or Landsat-8 values. This is useful if trying to take models and thresholds fitted from Landsat and use them with Sentinel-2. The fitted adjustment equations were also compared against those fitted globally for NASA's Harmonized Landsat-8 Sentinel-2 product, and found to be substantially different, raising the possibility that such adjustments need to be fitted on a regional basis.
Article
A pixel‐level fusion technique for RGB representation of multispectral images is proposed. The technique results in highly correlated RGB components, a fact which occurs in natural colour images and is strictly related to the colour perception attributes of the human eye. Accordingly, specific properties for the covariance matrix of the final RGB image are demanded. Mutual information is employed as an objective criterion for quality refinement. The method provides dimensionality reduction, while the resulting RGB colour image is perceptually of high quality. Comparisons with existing techniques are carried out using both subjective and objective measures.
Article
The principles that guided the founders of the CIE 1931 system for colorimetry are examined. The principles are applied to the Wright-Guild experimental determinations of the color mixture data to show in detail how and why each step in the development of the CIE 1931 system for colorimetry came about. These steps are examined in the light of 65 years advanced knowledge of colorimetry. The necessity for each of these principles in the modern world is examined critically to determine whether one might hold to the same principles if the system were being freshly formulated today. © 1997 John Wiley & Sons, Inc. Col Res Appl, 22, 11–23, 1997.
Article
The new international standards, which define a standard observer, three standard illuminants, standard conditions of illuminating and viewing opaque specimens, a standard for evaluating the brightness factor of opaque specimens, and a standard trichromatic system for the expression of colour measurements, are stated and their origin explained. In addition to the numerical tables which are appended to the resolutions setting up these standards, there are given a table specifying the trichromatic coordinates for the standard observer of all spectral colours at wave-length intervals of 1 mμ, tables to facilitate the calculation of the standard coordinates and the brightness factor of a material illuminated by any one of the three standard illuminants from spectrophotometric measurements on the material, and a table giving the coordinates of some stimuli of special importance on the N.P.L. system, the standard system, and another system which occurs in the resolutions. Some new colorimetric terms are proposed, partly to avoid misinterpretation and partly to meet new needs. The theory of colour transformations, and points which arise in the application of the system and in the calibration of instruments, are discussed.
The ASTER spectral 374 library version 2.0. Remote Sensing of Environment
  • A Baldridge
  • S Hook
  • C Grove
  • G Rivera
Baldridge, A., Hook, S., Grove, C., Rivera, G., 2009. The ASTER spectral 374 library version 2.0. Remote Sensing of Environment 113 (4), 711715.
Neuroscience: Exploring 376 the Brain
  • M F Bear
  • B W Connors
  • M A Paradiso
Bear, M. F., Connors, B. W., Paradiso, M. A., 2007. Neuroscience: Exploring 376 the Brain, 3rd Edition. Lippincott Williams & Wilkins.
Sentinel-2 adds colors to the 2017 super bloom in Califor390 nia
  • S Gascoin
Gascoin, S., 2017. Sentinel-2 adds colors to the 2017 super bloom in Califor390 nia. http://www.cesbio.ups-tlse.fr/multitemp/?p=10340 (accessed 15
Multimedia systems and equipment Colour measure393 ment and management Part 2-2: Colour management Extended RGB 394 colour space-scRGB
IEC 61966-2-2, 2003. Multimedia systems and equipment Colour measure393 ment and management Part 2-2: Colour management Extended RGB 394 colour space-scRGB. Tech. Rep. 61966-2-2:2003, International Electrotech395 nical Commission.
Preliminary Comparison of Sentinel-2 and 397
  • E Mandanici
  • G Bitelli
Mandanici, E., Bitelli, G., 2016. Preliminary Comparison of Sentinel-2 and 397
Digital Color Imaging Handbook
  • G Sharma
  • R Bala
Sharma, G., Bala, R., 2002. Digital Color Imaging Handbook. CRC Press, Inc., 401