Fabric Pilling Objective Evaluation Based On Wavelet Analysis

The objective grading of fabric pilling based on wavelet analysis is investigated theoretically and experimentally in this thesis.Feasibility of wavelet analysis theory used for fabric pilling image processing is probed into theoretically and positive conclusion is made. Using wavelet analysis for fabric pilling images processing can inspect periodic structures in the image (the fabric weave/knit pattern) as well as nonperiodic structures in the image (the pills).Based on the theoretical analysis a new method of frequency domain analysis by the wavelet analysis to objectively measure pilling intensity in sample images is proposed. Wavelet Analysis Model of Fabric Pilling Image is established, a preliminary evaluation of the method based on analysis of two series of standard pilling evaluation test images is done, a developmental method for selecting an optimal analysis wavelet and complementary analysis scale for a given pilling classification case is presented. The research results show that Wavelet Analysis Model of Fabric Pilling Image is feasible, that the ability of the model to discriminate between levels of pilling intensity depends on the wavelet analysis scale being closely matched to the fabric interyarn pitch. Compared with previous image analysis techniques described in the sources, the method has the superiority that it requires only a single-step analysis to produce a quantitative measure of pilling intensity.Wavelet Analysis Model of Fabric Pilling Image is further evaluated, and its sensitivity to horizontal and/or vertical translations and variations in the brightness of the image, and rotation and dilation of the image being analyzed are investigated. The results indicate that the Mode is receptive to small horizontal and/or vertical translations and to normal variations in the brightness of the image under analysis, and is sensitive to rotation and dilation of the image. These results suggest that as long as precautions are taken to ensure that samples are imaged under consistent conditions of weave/knit pattern alignment (rotation) and apparent interyarn pitch (dilation), the Model will yield repeatable results.The Pillgrade system was used to objectively characterize the pilling propensity of a range of knitted fabric samples, and the results are compared with those obtained from conventional subjective pilling assessments. The comparative study between instrumental and subjective grading leads to some new conclusions, that is, pilling tendency of smooth or simple structure fabrics is lower than that of rough or complex structure fabrics; thin fabrics' pilling propensity is less seriously than thick fabrics.