MEASUREMENT OF POROSITY AND THE CHOICE SELECTION OF THE THERESHOLD VALUE THROUGH THE IMAGE ANALYSIS

摘要

Pores are characterized as small air holes among the weave points in the fabric. Pore size is expressed by the indicator of porosity. Fabric porosity has a decisive influence on the properties and utilization of fabrics. Therefore it is necessary to be identified and measured in several ways. In this work one possibility of porosity measurement of the fabrics has been studied. Picture analysis NIS Elements consisting of Nikon microscope, CCD camera and related software were used for measurement. During porosity measurement the fabric surface was compared to that of pores. Scanned picture was divided into the surface of pores and that of a fabric. For division it was necessary to choose the correct threshold value of a scanned picture. The result of experimental measurements was the choice of the threshold value of a scanned binary picture, which will ensure a bigger objectivity and repetition of porosity measurements.