Until recently, there were primarily two methods utilized in quality control and research facilities, to provide objective color analysis of objects. In a colorimeter like the PhotoVolt 577A pictured in Fig 1, light is reflected off of the objects surface, and then passed through red, green, and blue glass filters (Tristimulus) , the amount of light passing through each filter then being measured and compared to a human simulation color model.
Fig.1 Photovolt 577A
Tristimulus Colorimeter
Some of the earliest color studies in coffee were done with a colorimeter, and the first standards for the coffee industry were actually developed with this method. They are recommended primarily for quality control applications, leaving research applications to be fulfilled by more complex technologies like the spectrophotometer. For evaluation of roasted coffee, they require about the same amount of sample preparation, and give results as meaningful and accurate as a spectrophotometer, in about the same amount of time, the difference being the way in which the results are gathered.
Fig.2 AGTRON SPECTROPHOTOMETER
The spectrophotometer, like this Agtron Unit, provides illumination, in this case in the NIR Range of the color spectrum, and then passes the reflectance to a grating, which then breaks the reflectance in to the spectrum.It measures the amount of light at each wavelength, which is then fit to a color model.
Fig. 3 COLORTRACK LASER REFLECTOMETER
The ColorTrack Analyzer Fig. 3 isn't classified as a spectrophotometer or colorimeter. Instead, it is a true reflectometer. Although a spectrophotometer is also a reflectometer, the distinction is that ColorTrack Technology does not operate in conjunction with a human simulation color model. It provides information on lightness and darkness in a relative color scale.
Because it uses laser (light amplification by stimulated emission of radiation) as the light source, and a patented algorithm technology, it is able to scan a moving sample, and provide reflection data based on 10, 000 readings per second.
