MARKET 1 Lecture Notes - Lecture 15: Alkyd, Scanning Electron Microscope, Data Comparison
Document Summary
Determination of colour varies with observer, with illumination conditions, etc. Colour needs to be an objective parameter (quantitative). Colour is a mixture of three monochromatic radiations (red/green/blue). There is a 3d classification for colours: hue: colour group, saturation: chroma, lightness: value. In order to be quantitative, there is a need for reflectance measurements. Reflectance can be diffuse or specular (gloss effect). Specular is when the angle at which the light hits the specimen, is exactly the angle at which light is reflected off the specimen. Illumination conditions become then important in order to obtain reliable and reproducible data, and in order to suppress the gloss effect so as to access the colour. There are different ways (geometries) to look at the sample: the light could come at an angle of 45 and exiting the sample at 90 (this can be called 0 ). This is a typical geometry for a microscope.
