Two things are the same structure when they compress better together than apart.
A model-free similarity measure. It extracts no features and is told nothing about what to look for — it asks only whether a compressor finds shared structure across two objects. Identical inputs read ~0; objects with nothing in common read ~1. The number means nothing in isolation, so this tool computes two reference anchors alongside yours and shows you where your pair lands between them.
AImage Adrop, paste, or click to choose
BImage Bdrop, paste, or click to choose
normalize to
—NCD ( A , B )
where your pair sits
Computed live from your two images: A vs itself fixes the zero end, A vs random noise fixes the far end. Your A↔B distance is placed between them, so the reading is scaled to these specific images, not an abstract 0–1.