Mix five example channels, or build your own source combination. Explore colour, tint and colour rendering.
Example spectra only — not Lightstec product measurements or calibrated driver settings.
Principles of mixing spectra
Every LED light is a sum of light sources. A mixer adds the individual spectral power distributions (SPD) of its channels to build one composite spectrum — and from that spectrum the viewer derives colour, tint and rendering.
1 · Linear channel mixing
Each channel has its own SPD, Ei(λ). Scaling a channel by its weight wi and summing gives the mixed spectrum: the higher a weight, the more that channel contributes to the total light.
2 · White point & colour temperature
Integrating the SPD against the CIE 1931 colour-matching functions gives the chromaticity (x, y). The correlated colour temperature (CCT) is the nearest black-body temperature on the Planckian locus; Duv is the signed distance from that locus — positive is green, negative is magenta.
3 · Colour rendering (CRI)
CRI scores how faithfully colours appear under a light. Eight standard pastel samples (R1–R8) are averaged into Ra; saturated red R9 is reported separately. Each score is the colour difference (ΔE) between the light and a perfect reference, scaled so 100 = no difference.
4 · Same CCT, different spectra
Two mixes can land on the same white point yet have very different SPDs — and therefore different CRI and tint. That is why a spectrum, not just a colour temperature, matters for visual quality.
Build a spectrum
Weights · 0–100
Colour temperature & rendering
Spectrum
Chromaticity
CRI R values · R1–R14
Read each score directly and compare the bar lengths. Ra averages R1–R8. Each mix is scored against its own CIE reference.
Keep a baseline, then change one channel
Save this mix as A. The dashed spectrum and blue colour-score markers will let you compare the effect of your next change.
No saved mix. Save a mix as A, then move a slider. Saved A stays fixed.
Keep the comparison
Calculations run in your browser. No sign-in required.
Good to know
How does Custom sources work?
Five-channel offers the fixed warm / cool / RGB example set. Custom sources lets you add or remove channels and adjust each weight directly — build any combination of the example spectra.
Can two mixes have the same colour temperature but different CRI?
Yes. CCT only tells you the white point. Two spectra that land on the same (x, y) can be built from completely different channels, and that changes how saturated colours are rendered — often dramatically for red (R9).
What does a positive or negative Duv mean?
Duv is the signed distance from the Planckian locus. Positive Duv sits above the locus — greener tint; negative Duv sits below — magenta tint. A value near 0 means the white is close to a black-body white at that CCT.
Why can the spectrum look unchanged when I raise every channel?
Because the SPD is scaled to its own peak. Raising every channel by the same factor scales the whole curve but keeps its shape — the relative power, white point and CRI stay the same.
Why do some mixes show “—” for CRI or colour temperature?
If all channels are off (or the total is too small), there is no meaningful spectrum to evaluate, so results are hidden rather than showing meaningless values.
Need a real spectrum for your project?
Tell us the model, CCT, output state and test conditions you need. Our team will help you match the light quality for your application.
Izvedite več strokovnih tečajev, ki vam jih pove manj ljudi, preden se zmotite.