Wavelength nm to Approx RGB
Approximate visible-wavelength display RGB using explicit piecewise artist heuristic and gamma/edge attenuation; no colorimetric spectral integration, actual monitor gamut equivalence or observer sensitivity curve.
Description
A visible-wavelength RGB approximation can use an artist’s piecewise heuristic.
A visible-wavelength RGB approximation can use an artist’s piecewise heuristic. Display colors cannot reproduce arbitrary monochromatic spectra.1
Enter wavelength 380–780 nm and positive gamma≤3. Use channel transitions at 440,490,510,580,645 nm and attenuation ramps 380–420/700–780 nm. Return RGB and attenuation; the middle region has attenuation 1 and endpoints 0.3.
When to use Wavelength nm to Approx RGB
Use Wavelength nm to Approx RGB when you need to evaluate the supplied records under the calculation and evidence rules below. No spectral colorimetric integration, sensitivity curve or actual monitor equivalence is supplied.
Prepare colors in the stated color space and scale. Use encoded RGB fractions, linear RGB, Lab, xy, byte values or ink percentages exactly as requested; supply caller tolerances and reference conditions.
How to use Wavelength nm to Approx RGB and understand its results
- Prepare colors in the stated color space and scale. Use encoded RGB fractions, linear RGB, Lab, xy, byte values or ink percentages exactly as requested; supply caller tolerances and reference conditions.
- Enter wavelengthNanometers, displayGammaHeuristic using the field table and calculation rules, then run the tool.
- Read approximateDisplayRgb, visibilityAttenuationFraction. The explanation below defines the units, signs, ordering and any flags or placeholder values.
- If the tool reports an input issue, correct the values and run it again. Apply the stated assumptions when interpreting a successfully returned result.
| Input field | Meaning | Value type; see rules below | Requirement |
|---|---|---|---|
| wavelengthNanometers | Wavelength nanometers | number | Required |
| displayGammaHeuristic | Display gamma heuristic | number | Required |
Enter wavelength 380–780 nm and positive gamma≤3. Use channel transitions at 440,490,510,580,645 nm and attenuation ramps 380–420/700–780 nm. Return RGB and attenuation; the middle region has attenuation 1 and endpoints 0.3.
output_i=(piecewiseChannel_i×edgeAttenuation)^gamma Units, indexing, boundary conditions and exceptional cases are defined in the calculation rules above.
| Output field | Meaning | Value type |
|---|---|---|
| approximateDisplayRgb | Approximate display rgb | list of number |
| visibilityAttenuationFraction | Visibility attenuation fraction | number |
{
"input": {
"wavelengthNanometers": 510,
"displayGammaHeuristic": 0.8
},
"output": {
"approximateDisplayRgb": [
0,
1,
0
],
"visibilityAttenuationFraction": 1
}
}Limitations and assumptions
No spectral colorimetric integration, sensitivity curve or actual monitor equivalence is supplied.
Numeric inputs, where present, must be finite. Follow the calculation-specific rules for overflow, underflow and exceptional cases. Missing required fields, extra fields, wrong value types and violations of the calculation rules are input errors.
Alternative or Complementary methods
Use Blackbody Kelvin to xy Chromaticity Approx: A bounded polynomial estimates Planckian-locus xy from blackbody temperature. A measured lamp need not follow that locus. For a complementary task, use CCT From xy Chromaticity Approx: McCamy approximate CCT uses an xy polynomial near a bounded domain. Not every chromaticity has a meaningful correlated temperature.
References
-
Wavelength nm to Approx RGB — tool.io
Similar or alternative tools
- Blackbody Kelvin to xy Chromaticity Approx
A bounded polynomial estimates Planckian-locus xy from blackbody temperature. A measured lamp need not follow that locus.
- CCT From xy Chromaticity Approx
McCamy approximate CCT uses an xy polynomial near a bounded domain. Not every chromaticity has a meaningful correlated temperature.