Figure 1

A typical scale-space image and the finger print map. A typical scale-space image with increasing σ (on the bottom) and the contours of the zero-crossing points of the second derivatives of the scale-space image (on the top) (adopted from [16]). The vertical dotted lines show the inflection points of the scale-space image at the lowest σ(=σ₀) and the horizontal arrowed lines, intervals at a σ(=σ _k ) between two neighboring inflection points, along with the corresponding points marked by “x” on the scale-space image at σ(=σ _k ).