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Using the app

Calibrating your setup

Calibration is how ScreenGuardian learns what good distance and posture look like for you, so its feedback fits your body and your desk instead of a generic average. It is deliberately low-friction: no tape measure, and nothing to type in.

Calibration sets two different references, and they are not the same thing:

  • Your screen distance, measured where you actually sit. The app then compares that to a comfortable ergonomic range and tells you if you are sitting closer than is easy on your eyes.
  • Your target posture, the upright position you want to hold. Later, posture feedback is measured against this reference, so it should be your best comfortable posture, not a slouch you are trying to break.

That difference matters. Distance is measured from where you really are, then coached. Posture is a goal you set. If you calibrate posture while slumped, the slump becomes your baseline and the app will never nudge you out of it.

Why it never asks you to measure

Some tools ask for your exact eye-to-eye distance or your height. ScreenGuardian does not, on purpose: measuring yourself is fiddly and easy to get wrong, and a wrong number quietly throws off every reading afterward. Instead it estimates distance from what the camera can see, and calibration anchors that estimate to your real setup.

The steps

  1. Set your distance. Sit at the distance you normally work, eyes open, looking at the screen. After the short capture the app tells you your distance and whether it is in the comfortable range, so you can adjust your setup if you are sitting too close.
  2. Set your target posture. Sit up the way you want to hold yourself while working: shoulders over hips, head level, tall but relaxed enough to keep for a real work session, not a stiff pose. This becomes the reference the app compares against, so aim for good, sustainable posture rather than your everyday habit.
  3. Hold still for the short capture; a duration option lets you pick how long.

You can redo either step any time from settings.

If a good posture is hard to hold

If sitting upright feels like a strain to sustain, that is usually the setup, not you: a laptop screen below eye level pulls your head down, a chair too low rounds your shoulders, a desk too high lifts them. Adjust what you can, screen near eye level, feet flat, back supported, then calibrate posture from there. Calibrating around a setup that fights good posture just teaches the app to accept it.

Good, even lighting helps too. If your face is in deep shadow or strongly backlit, move a light or turn to face your main light source before calibrating.

When to recalibrate

Redo calibration if your setup changes in a way that moves your face relative to the camera: a new monitor or laptop, a different chair height, or moving the webcam. You do not need to recalibrate day to day; small shifts are handled automatically.

Common questions

Does calibration store a photo of me?

No. Camera frames are processed in memory and are never saved or uploaded. Calibration keeps a small set of reference values, not imagery. See your data and privacy.

My distance readings look off. What now?

Recalibrate in normal lighting, sitting at the distance you want to treat as your baseline. If it still looks wrong, send feedback from Help in the app so we can take a look.