| **Brightness** | 30 – 230 (0–255 scale) | Under- and over-exposure |
| **Contrast** | Score ≥ 30 | Flat, low-detail images |
| **Pupil confidence** | ≥ 30% | Frame contains a detectable pupil |
| **Centre offset** | ≤ 25% of frame | Pupil not centered enough |
**Status indicators**
– 🔴 Red border + live feedback message — one or more criteria failing; hold still and adjust position
– 🟡 Amber — borderline; minor adjustment needed
– 🟢 Green border — all criteria met; photo is captured automatically
**”Not an Eye” rejection**
Even after automatic capture, a secondary AI check confirms the image contains an iris/pupil. If a non-eye image is detected (fingers, floor, clothing), a warning dialog appears with the option to retake.
**Tips for best results**
– Stabilize the device — even small hand movement drops sharpness below threshold.
– Ensure even lighting; avoid direct sunlight on one side.
– Position the iris in the center of the frame before getting close.
– Allow 2–3 seconds for the auto-exposure to settle after moving the camera.
