Abstract
The Weathering Steel with its properties of rust is resistant to atmospheric corrosion.Because of a rust layer produced on the steel is compact and stable. The steel using without coating is very economical and superior from the viewpoint of saving materials and energy.However, the rust on Weathering Steel is influenced by the environment. Therefore it is necessary to inspect and examine the steel after construction. There is a evaluation of outward rust as the method. And the method is evaluating the rust from Level 1 to Level 5. But there are some points at issue of the method. It is that evaluation is changed by subjectivity of a person evaluating the steel.In the present study, it proposed the method of distinguishing the rust appearance evaluation that used the picture processing as a technique for solving the problem.
