Extraction of subpixel insect wing features in images

Wing vein, junction of veins and wing edges are the fundamental image features for wings 3D reconstruction to obtain insect deformations motion parameters. To determine precise position of the wing features in images, gray properties of wing features were analyzed first. For wing vein features, the gray extreme direction was determined by Hessian matrix. The gray variable was fitted by conic curve along the direction of the gray extreme, so the subpixel location of the vein center was obtained by searching the extremum of the curve. For wing edges, image gray gradient was calculated, and then subpixel step edge of wings was determined by searching the gradient extremum along the gradient change direction. Angle constraint in neighbor was used to determine junctions of wing veins based on the change continuity of vein direction. All wing features were determined at subpixel locations. The experimental results show that the extracting method about wing features is effective.