PhysLight Explorer

Lightsaber data

Drop a spectrum on a real camera's measured R/G/B sensitivities. Same light, different sensors — that's metamerism.

Daylight WB

Raw response

Camera A

Camera B (compare)

Light source

Planck SPD · drag Kelvin

Colour temperature

5600 K

3200

5600

6500

10k

Canon EOS R5

WB linear RGB

1.00

0.83

0.68

1.000, 0.832, 0.684

Sony ILCE-7SM3

WB linear RGB

1.00

0.86

0.71

1.000, 0.855, 0.709

Human (CIE 1931)

What a standard observer would report as the colour of this SPD — cameras rarely match this exactly.

Macbeth ColorChecker under this light

24 patches · Ohta 1997

Spectral reflectance × illuminant × camera sensitivities. Compare cameras to the CIE reference row — that's metamerism on a chart you already know.

Camera A · EOS R5

Camera B · ILCE-7SM3

CIE 1931 reference (Display P3)

Export Nuke ColorMatrix

.nk

Least-squares 3×3 fit from Camera A RGB to a target, using the 24 ColorChecker patches under the current illuminant. Paste into Nuke's Node Graph (or a .nk file). Educational — not a lab camera profile.

Cam A → CIE XYZ

Cam A → Cam B

0.5914  0.0371  0.1577
0.2339  0.8134  -0.2338
0.0475  -0.3003  1.3613

Mean relative residual: 1.6% · EOS R5 → CIE XYZ (rel. Y) · 5600 K blackbody

Preview Nuke script

# PhysLight Explorer → Nuke ColorMatrix
# Educational fit from measured camera spectral sensitivities × ColorChecker reflectances.
# Not a production camera profile. Validate before use.
# Fit under 5600 K blackbody; daylight-WB camera RGB → CIE XYZ (rel. Y); ColorChecker Classic (Ohta 1997) 24 patches
ColorMatrix {
 matrix {
		{ 0.59141067 0.03706286 0.15765617 }
		{ 0.23390597 0.81338272 -0.23382498 }
		{ 0.04753048 -0.30033174 1.36129747 }
 }
 name PhysLight_Canon_EOS_R5_to_XYZ
 label "EOS R5 → CIE XYZ (rel. Y) · 5600 K blackbody"
}