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New possibility of objective evaluation of yarn appearance: part II

Moučková E., Jirásková P.

Autex Research Journal

2013

Vol. 13, no. 1

1--10

In this article, the possibility of new objective evaluation of yarn appearance in area employing selected spatial statistical functions is presented. The yarns wound on the boards were used for the experiment. Appearance of standard yarn boards from the standard CSN 80 0704 and real yarn boards with faultless and faulty yarns were converted into grayscale images. Fluctuation in degrees of grayness was evaluated between square fields in the image using statistical function called the area variation curve. In addition, the method was applied to the simulated yarn board appearance generated by the Uster Tester apparatus. Behavior of area variation curves in dependence on the result of visual evaluation of yarn board appearance was discussed. The generated appearances from the Uster Tester device were also evaluated by other statistical function called semivariogram. It was found out that the area variation curve is not a suitable tool for evaluation of yarn board appearance. The semivariogram seems to be a more suitable tool. The paper extends the knowledge on the issue of objective evaluation of yarn appearance and directly follows the author’s work [1].

New method for the evaluation of woven fabric unevenness

Jiraskova P., Moučková E.

Autex Research Journal

2010

Vol. 10, no. 2

49--54

Unevenness of woven fabric results from irregularity of the yarn used as well as from the process of its manufacture(weaving). A periodical and non-periodical yarn irregularity shows itself in the flat textile by known effects - themoiré effect, cloudiness, and stripiness. It is possible to predict the appearance of flat textiles from measured values of yarn mass irregularity and their characteristic functions (a spectrogram, a variance-length curve). The evaluation of surface unevenness of woven fabrics is done not directly but by judging their appearance, most often subjectively. For evaluation of flat textile appearance, it is also possible to use a so-called area-variation curve. The curve can be constructed on the basis of analysis of a woven fabric image either by a special program, created by J. Militky (Technical University of Liberec) in the programming environment Matlab, or by means of image analysis. By these methods it is possible to evaluate an image of real flat textile as well as a simulated image from an apparatus for yarn irregularity measurement. The woven fabric image is in grey scale. The variation coefficient of greyness degrees expresses the unevenness of flat textiles. In the experiment both real woven fabric images and simulated appearances of woven fabric, obtained by means of the apparatus Uster Tester IV, are evaluated by the methods mentioned above. The acquired area-variation curves are compared with each other and compared with visual evaluation of the woven fabric image. It was found that area-variation curves show only marked unevenness of woven fabric.