Image analysis of standard pilling photographs using wavelet reconstruction

A new approach to pilling evaluation based on the wavelet reconstruction scheme using undecimated discrete wavelet transform (UDWT), which is shift-invariant and redundant, was investigated. A method of digital image analysis to attenuate the repetitive patterns of fabric surface and enhance the pills is presented. A preliminary evaluation of the proposed method was conducted to SM50 European standard pilling images. The results show that reconstructed resolution level, wavelet bases and subimage used for reconstruction can affect the segmentation of pills and thus pilling grading. The area ratio of pills to total image was effective as a pilling rating factor. The results suggest that the proposed method in this paper is applicable to the practical evaluation of pilling.