Estimation of the surface concentration of adhered particles by color imaging

The surface concentration of adhered particles on flat or approximately flat surfaces can be estimated, non-destructively, by color imaging. Images in which the color is specified by the common RGB (red, green, blue) coordinates can be used when there is a sharp contrast between the color of the powder particles and that of the host surface. In the absence of sharp contrast, identification of the powder covered area is much easier after the color has been transformed into HST (hue, saturation, intensity) coordinates. The actual determination is done by creating a curve depicting the relationship between surface concentration and the fraction of covered area. It is practically linear at low concentration and becomes increasingly concave upward as the concentration increases, a result of particle aggregation and multi-layered coverage.