DECISION FOR GLOSS OF OBJECT SURFACE

PURPOSE:To enable decision on the gloss quantitatively in a wide coarse range while making the decision match closer with the visual gloss about objects of the same color, by setting the wavelength and the incident angle so that the dispersion satisfies a specified formula in the height distribution of the surface profile to be measured to detect the intensities of direct reflection and the intensities of total reflection of two luminous fluxes projected. CONSTITUTION:For example, the wavelengths lambda1 and lambda2 and incident angles theta1 and theta2 are set so that the dispersion sigma satisfiers the relationship of the formula in the height distribution of the surface profile of an object to be measured such as stainless steel plate and two luminous fluxes with the wavelengths lambda1 and lambda2 are projected to the surface of the object being measured at the incident angles theta1 and theta2 to detect the intensities I1 and I2 of direct reflection and the intensities S1 and S2 of total reflec tion thereof respectively. Then, representative points of individual visual glosses are plotted on 2-d planes (I1/S1, I2/S2) beforehand and connected together smoothly to determine the curve l. Based on the straight line (m) perpendicular to the curve l, the gloss of the desired object being measured is disciminated. Thus, the gloss can be quantitatively decided on in a wide coarse range thereby permitting the measure ment and management of the surface quality online.