Oily shine
Specular highlight fraction (T-zone)
A proxy for surface oil and shine: the percentage of T-zone pixels that come out near-white and low in saturation.
Also searched as oily skin, shiny T-zone and greasy forehead.
How to read it
few T-zone pixels come out near-white: little shine in this photograph.
a moderate share of the T-zone comes out near-white.
a large share of the T-zone comes out near-white: visible shine in this photograph.
Also captures direct flash reflection.
Why every value has an error bar
Every value Canthion reports carries a 1σ uncertainty propagated from MediaPipe Face Mesh's published accuracy (3.96% of inter-ocular distance mean absolute error per landmark, Kartynnik 2019). On a typical photo with 300 px between the pupils, that is about 12 px of wander on every point. Small ratios and angles inherit it, so their intervals are wide. A number without an interval is a number pretending to be more precise than it is.
Common questions
What is oily shine?
A proxy for surface oil and shine: the percentage of T-zone pixels that come out near-white and low in saturation.
How is oily shine measured from a photo?
From the pixels of the photograph, not from landmarks: the region (T-zone) is converted to CIE L*a*b* and the value is read as a statistic of those pixels. Because it depends on lighting, it is reported relative to the rest of the same photograph and marked lighting-dependent.
How reliable is oily shine from a photograph?
Skin values depend on the light the photograph was taken in, so they are reported relative to the rest of the same photograph and never as an absolute. Also captures direct flash reflection.
Related measurements
The rest of the skin set, then the nearest measurements elsewhere on the face. Every one is computed on the same photograph, in the same run, with its own error bar.
Also: how bone-level measurements are taken from a photo · methodology · glossary · all 35 insight pages