Iris Spectrodensitometer measures spectral wavelengths and gets density readings This instrument can provide readings that help to view all the light that the human eye can see, so there are many applications for human perception such as in ink printing, film processing, textile printing, and dyeing, plastic electronics, and other industries for color measurement and quality control; especially suitable for the measurement and quality control of optical density and dot enlargement in ink printing industries. This works by aiming at a light source designed at a photoelectric cell.