Fabric Pilling Hairiness Extraction From Depth Images Based on the Predicted Fabric Surface Plane

A new approach for extracting the hairiness from fabric based on the predicted fabric surface plane is presented in this paper to extract the hairiness from the depth image. The depth from focus (DFF) technique is utilized in this study to establish the depth image of the pilled fabrics by using a series of image layers captured under a microscope. A pilled fabric depth image provides information on the hairiness and the fabric surface, and the hairiness is located above the fabric surface. However, the depth value of the fabric surface covered with hairiness cannot be directly obtained. Therefore, for hairiness extraction, a predicted plane of the fabric surface is fitted by selecting several base points on the fabric surface. The target above the predicted plane will be considered as hairiness and will be extracted. The oversegmentation method based on the mean shift algorithm is used in the study to select the base points of the fabric surface. First, several seed points are marked along the Sobel edges; then, several oversegmented areas are formed after the growth of the seed points, which are called split pieces in this paper. The split pieces of the fabric surfaces are selected as the base points according to the depth value as well as the spatial direction of each split piece. Finally, the predicted plane of the fabric surface is established using these base points. The results of significance testing show that is it reasonable to assume that the fabric surface can be expressed as a plane. The results of the residual examination show that the predicted plane can correctly calculate the depth value (z) of the fabric surface at any plane position (x, y). The extracted hairiness images show that hairiness can be correctly and completely obtained through the predicted plane.