METHOD OF EVALUATING PRECOATED STEEL SHEET FOR BUILDING MATERIAL

摘要

PURPOSE:To know quantitatively a change in color or rusting of a precoated steel sheet for a building material by an image processing and to perform objective evaluation by a method wherein a color image represented by numeric values is subjected to geometric computation in the three-dimensional space of color and a sound part and a deteriorated part are processed to be discriminated on the basis of a threshold values set beforehand. CONSTITUTION:First, a color image of a precoated steel sheet for a building material is picked up. Then, this image is made to be represented by numeric values and inputted to a computer or an image processing device. An image slicing processing for removing parts unnecessary for analysis from this numerical image is executed. Thereafter the numerical image is expressed by analytical values showing deterioration and rusting, by geometric computation in the three-dimensional space of color. Based on these analytical values, it is determined and discriminated according to a threshold value set beforehand whether the part of the image is a sound part or a deteriorated part. Thereafter the area rate of the deteriorated part in the whole is computed and classified roughly and the degree of deterioration is computed.