Film datasheets
and resolution research

What the evidence supports

Calculation rules

Relative saturation change

100 * (S_film / S_reference - 1). Undefined when reference saturation is zero; unstable near zero. This is not the same as a percentage-point difference.

Aggregation

The mean of patch ratios is generally not the ratio of mean saturations. An unweighted average of six hue labels cannot reproduce an undocumented aggregate of chart patches. No aggregate is calculated from the retired profiles.

Hue direction

A hue error wraps at 360 degrees: 359 to 1 degrees is a 2-degree change, not 358. Fixed-axis saturation plots discard this dimension and cannot establish color accuracy.

Density

D = -log10(T). Density is logarithmic transmission, not an RGB channel value or a saturation multiplier.

Color-reference accuracy

The red, yellow, green, cyan, blue and magenta interface colors are category labels, not measured SpyderCHECKR swatches. A ratio-one baseline is a mathematical reference, not a calibrated physical target. HSL is not perceptually uniform. W3C color specification.

Use the correct target edition and patch IDs, documented reference values and illuminant, a color-managed scan pipeline, and matched comparison conditions. Evaluate lightness, chroma and hue, with a validated color-difference implementation such as CIEDE2000 where appropriate. A screen capture cannot establish a film's spectral response. Datacolor target guide / Colour implementations.