A two-stage binarizing algorithm for automatic 2D:4D finger ratio measurement of hands with non-separated fingers

2D:4D finger ratios are commonly measured manually. Previous automatic methods have relied on the fingers being spread apart for successful detection. This study proposes an improved automatic finger-ratio measurement approach that does not require the fingers to be spread apart. The approach comprises a two-stage binarizing algorithm. First, the hand is separated from the background. Second, the various fingers are separated such that a unique outline of the hand can be obtained and thus the 2D:4D finger ratio can be measured. The algorithm achieves accurate results of 66% on a test-suite of flatbed scans of two-hand images. Automatic validation of measurement quality is also discussed.