CCT From xy Chromaticity Approx
Compute McCamy approximate CCT from physical xy inside explicit caller bounded polynomial n-domain; not a universal temperature for any chromaticity or standards-grade CCT/Duv validity certification.
Description
McCamy approximate CCT uses an xy polynomial near a bounded domain.
McCamy approximate CCT uses an xy polynomial near a bounded domain. Not every chromaticity has a meaningful correlated temperature.1
Enter physical xy with 0<x,y<1,x+y≤1 and positive absolute-n ceiling≤10. Reject the singular denominator, out-of-domain n or nonpositive result. Return approximate Kelvin.
When to use CCT From xy Chromaticity Approx
Use CCT From xy Chromaticity Approx when you need to evaluate the supplied records under the calculation and evidence rules below. No universal chromaticity thermometer, nearest-locus search or standards-grade CCT/Duv validity is established.
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 CCT From xy Chromaticity Approx 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 measuredXy, callerMaximumAbsoluteN using the field table and calculation rules, then run the tool.
- Read mccamyApproximateCctKelvin. 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 |
|---|---|---|---|
| measuredXy | Measured xy | list of number | Required |
| callerMaximumAbsoluteN | Caller maximum absolute n | number | Required |
Enter physical xy with 0<x,y<1,x+y≤1 and positive absolute-n ceiling≤10. Reject the singular denominator, out-of-domain n or nonpositive result. Return approximate Kelvin.
n=(x−0.332)/(y−0.1858); CCT=−449n³+3525n²−6823.3n+5520.33 Units, indexing, boundary conditions and exceptional cases are defined in the calculation rules above.
| Output field | Meaning | Value type |
|---|---|---|
| mccamyApproximateCctKelvin | Mccamy approximate cct kelvin | number |
{
"input": {
"measuredXy": [
0.332,
0.4
],
"callerMaximumAbsoluteN": 2
},
"output": {
"mccamyApproximateCctKelvin": 5520.33
}
}Limitations and assumptions
No universal chromaticity thermometer, nearest-locus search or standards-grade CCT/Duv validity is established.
Numeric inputs, where present, must be finite. Follow the calculation-specific rules for overflow, underflow and exceptional cases. Numeric lists are limited to 10,000 entries; string lists to 128 strings of at most 128 characters each. The rules above may impose smaller limits. 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 Planckian Track Duv Approximation: A local Planckian displacement projects measured chromaticity onto a normal at a chosen reference temperature. It is an approximation to Duv near that reference.
References
-
CCT From xy Chromaticity Approx — 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.
- Planckian Track Duv Approximation
A local Planckian displacement projects measured chromaticity onto a normal at a chosen reference temperature. It is an approximation to Duv near that reference.