ARCMINUTE VISUAL ACUITY MATHEMATICS
Pixel Density, Visual Acuity & Retina Threshold Mechanics
The human visual system's spatial resolution limit is defined by the angular resolution of foveal cone photoreceptors, typically benchmarked at 1 arcminute (1/60th of a degree, or 0.01667°) for 20/20 Snellen acuity. When a monitor's pixel pitch is smaller than the spatial angle subtended by 1 arcminute at a given viewing distance, individual pixels resolve as a continuous, organic image — a threshold popularized as a 'Retina Display'.
MATHEMATICAL DERIVATION
PPI = √(Width² + Height²) / Diagonal_Inches
Retina Distance (cm) = 3438 / PPI
Where 3438 represents the radian multiplier derived from (180 × 60) / π arcminutes.