The problem with selfies
Light, angle and distance change how skin looks. A warm bulb hides redness, a window exaggerates texture, and a phone held ten centimetres closer makes every spot bigger.
A number that moves with the light tells you nothing about your skin. So before Saecra measures anything, it makes the photos comparable: same distance, same angle, same kind of light.
The pipeline
Every daily photo goes through the same six steps, entirely on your phone. Here they are on a single photo.
Capture
5-frame burst, guided distance, angle and light.
Quality check
Rejects blur, bad exposure, color cast and head tilt.
Align
478 face landmarks map every photo onto the same face.
Measure
Blemishes, fine lines, dark spots, inside the skin map only.
Consensus
Keeps only what most frames agree on.
Compare
Against your history, with a margin of change.
Fig. 1b Six steps, all on your phone
The margin of change
Every measurement wobbles a little, even when nothing changed. We measure that wobble on repeat photos of the same face, and we only call a change real if it is bigger than the margin.
MDC95 = 1.96 × √2 × SEM
MDC95 is the smallest change we can tell apart from noise with 95% confidence. SEM is how much a measurement wobbles on repeat photos of the same face.
Real change
Fig. 2 Illustrative margin. Real margins are published per measurement in the stability report.
Across skin tones
A measurement isn't ready until it works across all ten. We report results for every group, including where we fall short.
Fig. 3 Monk Skin Tone scale, 10 groups
On your phone
- Where it runs
- On your iPhone, on-device
- Photos uploaded
- 0
- Network calls while measuring
- 0
- What we store
- Nothing. Your history lives on your phone.
- What you can export
- Everything, any time
What we will publish
For each measurement: how much it moves on repeat photos, how it performs on every skin tone group, and what it still gets wrong. Good or bad, it goes on this page.
Stability report
In progress.
Get one email when the first report is published.
Every number in Saecra has to earn its place.