pigmented colorants: dependence on media and time - Cornell ...

More documents

Recommendations

Info

the normal for every point is calculated, via averaging the results from two cross products. The vectors are made from the current point’s three-space coordinates (x, y, height) to the four immediately surrounding points. Each pixel undergoes the same rendering pipeline. First, K S mix 191 is calculated as a weighted average of the pigments using their respective concentrations in the mixture from Equation A.16. Reflectance and transmittance of the layer is then calculated: b = R = K S 1+ K S K S +2 1 + bcoth(bSd) where d represents the thickness of one layer of paint (7.3) (7.4) T = bR csch(bSd) (7.5) Compositing multiple layers together (as well as the gesso ground) is done via Equation A.25. If no pigments are present at a given pixel, the reflectance is solely the three-coat gesso. XY Z integrating functions are used to transform the eight wavelength reflectance values for display. Since K-M theory only gives us diffuse reflectance, the lighting computation is completed using Blinn-Phong specular highlights: X = X (n · l)+E ¯x (n · h) k Y = Y (n · l)+E ¯y (n · h) k Z = Z (n · l)+E ¯z (n · h) k (7.6)
where n is the normal at the current point l is the vector from the current point to the light (l + e) h = is the half-vector, which avoids calculating the reflection vector 2 e is the vector from the current point to the camera E is the spectral distribution of the illuminant {¯x, ¯y, ¯z} are the observer matching functions k is the specular exponent which controls the shininess of the material Note that the Blinn-Phong shading model’s use of an exponentiated cosine is an ad hoc approximation to specular highlights. A physically accurate model of specular behavior would require a full temporally-varying BRDF for every sample. The XY Z color is transformed into linear RGB values for display using the transformation matrix M from Equation 3.6. These values are then converted to nonlinear sRGB before outputting to the display: ⎧ ⎪⎨ 12.92Rl ,Rl≤ .0031308 Rs = ⎪⎩ 1.055R 1/2.4 l − 0.055 , otherwise ⎧ ⎪⎨ 12.92Gl ,Gl≤ .0031308 Gs = ⎪⎩ 1.055G 1/2.4 l − 0.055 , otherwise ⎧ ⎪⎨ 12.92Bl ,Bl≤ .0031308 Bs = ⎪⎩ 1.055B 1/2.4 l − 0.055 , otherwise where {R, G, B} l are the linear RGB values 192 (7.7) The implementation runs interactively on a 3.4GHz Pentium IV machine with a NVIDIA GeForce 6800 GT graphics card. The cost of the rendering is greatly
Page 1 and 2:
PIGMENTED COLORANTS: DEPENDENCE ON
Page 3 and 4:
ABSTRACT We present a physically ba
Page 5 and 6:
Acknowledgements This work would no
Page 7 and 8:
Table of Contents 1 Introduction 1
Page 9 and 10:
List of Tables 2.1 Average pigment
Page 11 and 12:
3.15 Photoreceptor absorption .....
Page 13 and 14:
B.15 Variation of spectral reflecta
Page 15 and 16:
corrode the surfaces of materials.
Page 17 and 18:
Figure 1.1: Detail of the Azor-Sado
Page 19 and 20:
However, since mural artwork is typ
Page 21 and 22:
at a very high quality (albeit limi
Page 23 and 24:
heterogeneous sum of very different
Page 25 and 26:
which linseed oil derives (the most
Page 27 and 28:
oration of a rigidly painted layer
Page 29 and 30:
ing will hit the ground and reflect
Page 31 and 32:
tion of paint tubes in 1841 and the
Page 33 and 34:
Figure 2.8: Natural pigments of ant
Page 35 and 36:
ecome more common recently. The Ame
Page 37 and 38:
A V = O(r2 ) O(r3 ) = 1 O(r) 24 (2.
Page 39 and 40:
Table 2.2: Pigment specific gravity
Page 41 and 42:
provide the underlying color to a p
Page 43 and 44:
though the speed of light in air is
Page 45 and 46:
In general, when light travels from
Page 47 and 48:
materials while lit from behind. Li
Page 49 and 50:
Table 2.4: Index of refraction η f
Page 51 and 52:
to completely congeal. Hence, these
Page 53 and 54:
ond together to form proteins. Exam
Page 55 and 56:
to its original state by any means.
Page 57 and 58:
While it has been used since the 19
Page 59 and 60:
organic binder found in more conven
Page 61 and 62:
3.1.1 Visible Light Spectrum Light
Page 63 and 64:
Figure 3.2: Hue, brightness and sat
Page 65 and 66:
measures how much light is reflecte
Page 67 and 68:
Figure 3.6: Additive color mixing o
Page 69 and 70:
Figure 3.9: The physical amount of
Page 71 and 72:
The vascular tunic lies on the wall
Page 73 and 74:
Figure 3.11: Cross section of the r
Page 75 and 76:
Not all areas have the same sensiti
Page 77 and 78:
identify and distinguish between va
Page 79 and 80:
that range between zero and full in
Page 81 and 82:
spectrum. This insures that the res
Page 83 and 84:
Figure 3.19: Graphical representati
Page 85 and 86:
X x = (X + Y + Z) Y y = (X + Y + Z)
Page 87 and 88:
color into the appropriate RGB colo
Page 89 and 90:
components in the image (the smalle
Page 91 and 92:
haviors of subtractive mixing and i
Page 93 and 94:
of perceptually equal sizes. Unfort
Page 95 and 96:
enabling one to transform between t
Page 97 and 98:
andwidth as converted signals are s
Page 99 and 100:
Figure 3.28: Retinal ganglion recep
Page 101 and 102:
example shown in Figure 3.28. Under
Page 103 and 104:
Figure 3.31: The work of Josef Albe
Page 105 and 106:
sensations for each trial and picke
Page 107 and 108:
Chapter 4 Previous Work There is no
Page 109 and 110:
different location. Subsurface scat
Page 111 and 112:
describes the scattering and absorp
Page 113 and 114:
only accounts for a small percentag
Page 115 and 116:
σ ′ t = σa + σ ′ s and α
Page 117 and 118:
104 Figure 4.4: A model of an alaba
Page 119 and 120:
effects or are too computationally
Page 121 and 122:
108 Figure 4.6: Results using Kubel
Page 123 and 124:
specifying pigments works adequatel
Page 125 and 126:
color representation, it is not fea
Page 127 and 128:
time. A metallic surface patina is
Page 129 and 130:
the system consisted of wetness and
Page 131 and 132:
or darkening enables the museum per
Page 133 and 134:
in front of a displayed work. Felle
Page 135 and 136:
light exposure. This effect is espe
Page 137 and 138:
over time. Perceptually, these hues
Page 139 and 140:
The rate of change of the concentra
Page 141 and 142:
over white grounds) suffer the grea
Page 143 and 144:
protects the deeper remaining color
Page 145 and 146:
light source. This method is used w
Page 147 and 148:
chemical smog and have been identif
Page 149 and 150:
Chapter 5 Preparation & Measurement
Page 151 and 152:
tending transparent pigments used i
Page 153 and 154: 140 Figure 5.1: Spectral reflectanc
Page 155 and 156: the requirements of the work at han
Page 157 and 158: 144 Figure 5.2: Left: Magnified vie
Page 159 and 160: Table 5.2: Relevant data regarding
Page 161 and 162: historically one of the best grades
Page 163 and 164: created far too strong of a binder,
Page 165 and 166: too brittle and cracking. While wor
Page 167 and 168: 154 Figure 5.4: Reflectance values
Page 169 and 170: 5.1.5 Painting After the layers of
Page 171 and 172: The gray card reflected 18% of the
Page 173 and 174: 160 Figure 5.8: The optical setup f
Page 175 and 176: Note that harmonics reflect at the
Page 177 and 178: Note that the calibration factors f
Page 179 and 180: Chapter 6 Experimental Results 6.1
Page 181 and 182: 168 Figure 6.1: Lapis Lazuli in dif
Page 183 and 184: (such as CIE standards C, D50, orD6
Page 185 and 186: 172 Table 6.2: Perceptual differenc
Page 187 and 188: 174 Figure 6.3: Munsell plots of La
Page 189 and 190: and j has a saturation of red rsat,
Page 191 and 192: 178 Figure 6.4: Variation of spectr
Page 193 and 194: visible spectrum are increasing at
Page 195 and 196: 182 Figure 6.5: Munsell plots of La
Page 197 and 198: trying to match color ca from the p
Page 199 and 200: as it ages. This is in direct contr
Page 201 and 202: teractive viewer. In our applicatio
Page 203: 190 Figure 7.1: Our simulated canva
Page 207 and 208: In summary, our implementation prov
Page 209 and 210: Chapter 8 Conclusion We have studie
Page 211 and 212: inks are beginning to find their wa
Page 213 and 214: Appendix A Derivation of K-M theory
Page 215 and 216: ∆i − =(K + S) idx 202 ∆j −
Page 217 and 218: Equation A.8 is now: Rearranging yi
Page 219 and 220: and if the paint is infinitely thic
Page 221 and 222: One concatenates the layers into a
Page 223 and 224: 210 Figure B.1: Cold Glauconite in
Page 225 and 226: Table B.1: Color conversions from t
Page 227 and 228: 214 Figure B.4: Munsell plots of Co
Page 229 and 230: 216 Figure B.5: Burnt Sienna in dif
Page 233 and 234: 220 Figure B.8: Munsell plots of La
Page 235 and 236: 222 Figure B.9: Red Ochre Tint in d
Page 239 and 240: 226 Figure B.12: Munsell plots of C
Page 241 and 242: 228 Figure B.13: Variation of spect
Page 243 and 244: 230 Figure B.15: Variation of spect
Page 245 and 246: Table B.13: Color conversions of Bu
Page 247 and 248: 234 Figure B.18: Munsell plots of C
Page 249 and 250: 236 Figure B.20: Munsell plots of R
Page 251 and 252: References [Alb71] Josef Albers. In
Page 253 and 254: 240 [GLL + 04] Michael Goesele, Hen
Page 255 and 256:
242 [KM31] Paul Kubelka and Franz M
Page 257 and 258:
[Rat72] Floyd Ratliff. Contour and
show all

pigmented colorants: dependence on media and time - Cornell ...

Create successful ePaper yourself

Delete template?

Save as template?