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Blink-Free Group Photo Probability Calculator — result sheet
Estimate the chance that every person has eyes open in one group photo and the number of shots needed for a chosen success probability.
Inputs used
Results
Visual chart
Breakdown
Calculation steps
Returned data table
Formula and methodology
Formula: Approximate one-person open-eye probability = 1 − blink rate × (closed-eye duration + exposure time) ÷ 60,000. One-frame all-open probability = one-person probability^people. Required shots = ceiling(log(1 − target success) ÷ log(1 − one-frame probability)); expected shots = 1 ÷ one-frame probability.
This is an educational independence model for planning a photo sequence. It treats each person's blink state as independent and uses a visible blink window; real timing, attention, shutter behavior, motion, and image review can produce different results.
This result follows the calculator's declared inputs, precision, validation boundaries, and model limits.
Input contract
- People in the photo — people; minimum 1; maximum 1000
- Blink rate per person — blinks/minute; minimum 1.0E-6; maximum 120
- Average closed-eye duration — milliseconds; minimum 0.001; maximum 5000
- Photo exposure time — milliseconds; minimum 0; maximum 5000
- Target chance of at least one good photo — %; minimum 1.0E-6; maximum 99.999999
Worked example
| Input | Value |
|---|---|
| People in the photo | 10 |
| Blink rate per person | 10 |
| Average closed-eye duration | 250 |
| Photo exposure time | 10 |
| Target chance of at least one good photo | 95 |
Under the independent model, one frame has about a 64.1% all-eyes-open chance and about 3 shots are needed for a 95% chance of at least one such frame.
Assumptions and limits
- Blink rate is an average per person and is entered in blinks per minute.
- Closed-eye duration and exposure time are treated as a combined window in which a blink can spoil a frame.
- The one-person blink-window fraction is small enough to remain below 100 percent.
- People blink independently and have the same rate and duration in this simplified model.
- Each shot is treated as an independent opportunity with the same one-frame success probability.
- The target percentage means at least one all-eyes-open frame in the requested series.
- Lighting, attention, camera focus, motion blur, expression, and shutter synchronization are not modeled.
- The result is a planning estimate and not a guarantee that a usable photograph exists.
- Measured or repeated local experience can be used to replace the default behavioral inputs.
- The page does not assess eyesight, eye disease, or any medical condition.
Calculator note
Source and methodology
Use the official WorldCalculate methodology policy for the source, formula, precision, and boundary standards behind this calculator.
Planning estimate, not financial, medical, legal, or professional advice. © WorldCalculate — reuse with attribution. Built and curated by Hassan ALRowaie.
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