Study On Objective Assessment System Of Fabric Pleat Grade

Pleat is formed by the iron or shrinking which is a curve with regular crests andtroughs, and it is widely used in clothing. The evaluation of fabric pleat is very important toassess the textile appearance and perfonnance. The traditional method of evaluation is subjective, which is observing the similarity of fabric sample and standard template by human vision. This kind of method is often influenced by subjective factorsand then leads to wrong results.So a study on objective evaluation for fabric pleat grade is very necessary.The photometric stereo technique is to calculate the surface shape from the same view point with different light sources to acquire more than 3 images. The method has been used in the evaluation of fabric crease grade which is similar to the fabric pleat. So the evaluation system based on photometric stereo technique is feasible.The objective assessment system of fabric grade includes image acquisition and image processing. The system of image acquisition is based on the principle of photometric stereo technique includea computer, a CCD camera and a set of light source devices. The whole processing system includes the obtaining of fabric data, image filtering, noise removal, the height of fabric surface recovery, fabric features calculation and the grade evaluation by Euclidean distance.The objective evaluation system of fabric pleat grade eliminates the subjective factors, so it can evaluate the grade of fabric pleat objectively, fast and accurately. The main contents are as follows:(1) An objective assessment system of fabric pleat grade has been developed, which integrates the image process and analysis program with the image-capturing device.(2) The photometric stereo technique has been described, such as the basic principles of photometric stereo, the solution of fabric surface normal vector and the height recovery of fabric surface shape. Then two kinds of height recovery methods, the integration algorithm and the differential one have been compared, and then the differential method has been modified which can improve the calculatingaccuracy of fabric surface height. (3) The height and sharpness were selected as the features of fabric pleat by calculating the correlation coefficients. Euclidean distance was used to evaluate the grade of fabric pleat which is simple, fast and accurate.(4) The Xystem three-dimensional scanner has been used to scan the fabric, and thenthe height and sharpness have been calculated which are the reference value of the results from photometric stereo algorithm.(5) The polyester-cotton blended fabric,cotton fabric, single rib knitted fabric and double ribs knitted fabric have been chosen to test the evaluation method. Then the evaluation results of these fabrics wereanalyzed. The results show that the correlation coefficient of subjective and objective is 90%. So this objective assessment system is effective especially for polyester-cotton blend fabric or cotton fabric.