CAM16 and Hellwig–Fairchild calculator
Compare what standard CAM16 and the 2022 Hellwig–Fairchild proposal predict for the same XYZ stimulus and viewing conditions. The calculation runs in your browser.
Results
Appearance correlates
Reference result for the example inputs.
| Correlate | CAM16 | 2022 proposal |
|---|---|---|
Lightness J | 59.1305 | 59.1305 |
Brightness Q | 232.561 | 79.1392 |
Chroma C | 49.8664 | 34.4892 |
Colorfulness M | 51.8353 | 45.5003 |
Saturation s | 47.2111 | 57.494 |
Hue angle h | 45.64 | 45.64 |
Shaded rows are redefined by the proposal. The columns use different scales, so their raw magnitudes are not a color difference and are not directly rankable.
Hue is shown only when the opponent response is large enough to distinguish a direction from floating-point cancellation.
Model implementation 1.2.1
What the models report
Both models describe appearance with lightness J, brightness Q, chroma C, colorfulness M, saturation s, and hue angle h. The proposal preserves J and h while changing the definitions and scales of the other four correlates.
The table reports appearance correlates rather than display RGB or a color-difference score. Comparing the columns shows how the formulations differ; it does not determine which one better predicts observers.
Why viewing conditions matter
The same XYZ can appear different as the adopted white, background, surround, or adapting luminance changes. Enter the conditions for the intended observation; they remain visible and editable beside the result.
Why compare the formulations
The 2022 proposal revisits linked brightness, chroma, colorfulness, and saturation relations in CAM16. Across the observer datasets reported in the paper, the proposal has higher coefficients of determination for brightness and chroma and a lower one for colorfulness. See the equation study for the equations and fit results.