Colour measurement devices are necessary for accurate colour communication. Visual evaluation of colour is subjective, affected by our memory and highly depends on the viewing conditions. Therefore, depending on the application, either spectrophotometers or colourimeters are used to accurately and objectively capture and communicate colour. Even though both spectrophotometers and colourimeters are used to measure colour, they work in very different ways and are used for different applications. Choosing the right colour measurement device depends on your application and price range, which requires a good understanding of both technologies.
A spectrophotometer measures the intensity of light over the entire spectrum by breaking up the spectrum of light into many small increments. This allows for an accurate measurement of the wavelength-by-wavelength properties of an object. The measurement contains colour information beyond that observable by the human eye.
Spectrophotometers are highly accurate and versatile but more complex than colourimeters. They allow for identifying metamerism by predicting colour appearance under differing illuminations. These instruments are generally, due to their complexity, more costly than colourimeters.
A tristimulus colourimeter on the other hand, tries to simulate the human eye. It uses three filtered sensors (RGB) to approximate the light-sensitive cones of the eye, responsible for colour vision. Because it only uses three filtered sensors, it acquires less information about the colour than a spectrophotometer.
Colourimeters have a lower price and are more compact. They work well for comparing similar colours under constant conditions and are often used for monitor calibration. However, colourimeters are not suitable for complex color analysis as they are not capable of identifying metamerism.