Visual crease recovery of cloth was investigated by the use of a gray scale image of creases created by color dot images. Creases were created by applying a load of 5 kgf for 30 min to folded plain cloths of acetate, polyester, cotton, flax, wool and silk. The angular second moment, contrast, correlation and entropy extracted from the gray level co-occurrence matrix were measured as visual feature parameters. The fractal dimension was determined from the fractal analysis of the relief of the curved surface of the gray level image. From these image information parameters, a parameter ratio was obtained as the ratio of the image information parameter at the time of
t to the initial time of
t0 to simplify comparison among samples. Each parameter ratio tended to change more or less rapidly with the initial passing of time, followed by a moderate change with time, implying that each parameter ratio depends on time exponentially. Therefore, a visual crease recovery index was introduced to describe the visual relaxation behavior of crease recovery from the analogy of mechanical stress relaxation behavior. Using an equation of exponential function with this index, curves were achieved when graphs of the parameter ratio against time were plotted. The visual crease recovery was discussed in relation to the visual features, indicating that a visual crease recovery index was useful for characterizing the visual recovery of creased cloths.
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