Fig. 5From: Combining multi-scale composite windows with hierarchical smoothing strategy for fingerprint orientation field computationThe OF estimated by using the composite block where the inner block is 9 × 9 and the outer blocks vary from small sizes to large sizes: a the original fingerprint image, b the outer block in 9 × 9 scale, c the outer block in 15 × 15 scale, d the outer block in 23 × 23 scale, e the outer block in 31 × 31 scale, f the outer block in 37 × 37 scaleBack to article page