faktel-core/io.github.cybersafetyid.faktel.core.quality/laplacianVariance

laplacianVariance

fun GrayImage.laplacianVariance(): Double

Focus measure: variance of the 4-neighbour Laplacian. Higher is sharper.

The value depends on resolution and content, so compare crops of a normalised size (Faktel resizes before scoring) and calibrate the threshold on your own devices.