A colorimeter is a tristimulus color measurement tool that provides an objective evaluation of color characteristics based on light passing through the primary filters of red, green, and blue. It simulates how the human eye percieves color.
How it works?
Using an internal light source, a colorimeter shines light down onto the surface of the sample. As the light reflects back up to the device, it passes through three filters: red, green and blue. These filters distill tri-stimulus (RGB) values that match how our eyes see color.
Colorimeters can be used to test the surface color of objects. They’re also used to specify color. Designers can carry them around to capture inspiration colors for use in their designs. However, colorimeters are limited in their capabilities. Since they are blind to metamerism (a common phenomenon that occurs when two colors appear to match under one lighting condition but not when the light changes), they aren’t ideal for all production applications, especially formulation.
A spectrophotometer is a more complex color measuring instrument that factors in light intensity as a function of the color. It performs full-spectrum color measurement, as opposed to a colorimeter’s tristimulus procedure, and generates color data that’s beyond observation by the human eye.
How it works?
A spectrophotometer works almost same way, except for one main difference – the filters. Instead of using three filters to determine the RGB values, spectrophotometers typically have 31 filters to measure the full color spectrum of visible wavelength range. These filters measure light in each of 31 different wavelengths to determine the color of the sample.
Spectrophotometers come in many shapes and sizes, from small handheld devices to large benchtop, to in-line devices used during manufacturing production. Since they can evaluate how color will be under different light sources, spectrophotometers are ideal for identifying metamerism.
Spectrophotometers can measure just about anything, including liquids, plastics, paper, metal and fabrics. There are three primary types 45º/0º instruments present light at a fixed angle to the sample, and can exclude gloss to most closely replicate how the human eye sees color. They are commonly used for measuring color on smooth or matte surfaces.
A spherical instrument presents diffused light and can measure both excluding gloss (SCE) and including gloss (SCI). They are commonly used for measuring color that has been applied to textured surfaces such as textiles, carpets and plastics, as well as shiny or mirror-like surfaces, including metallic inks, printing over foil, and other highly glossy surfaces.A multi-angle spectrophotometer presents light at a single angle but measures at multiple angles – It is essentially used for color measurement of metallic and pearlescents pigment such as nail polish and automotive coatings.
Colorimeter Vs Spectrophotometer
|An instrument for psychophysical analysis which provides measurements that correlate with human eye-brain perception. Colorimetric data directly read and provide tristimulus values such as XYZ, L, a, b, etc.||An instrument for physical analysis which provides wavelength by wavelength spectral analysis of reflecting and/or transmitting properties of objects without interpretation by human. It can indirectly calculate psychophysical information.|
|It consists of sensor and data processor.||It consists of sensor plus data processor or computer with application software|
|It has a set illuminant and observer combination usually D65/10°||It has many available illuminant/observer combinations which can be used for calculating tristimulus data and metamerism index.|
|Extract tristimulus (RGB) values that match the colors seen by our eyes and convert to LAB||It isolates narrow band of wavelengths using prism/grating/interference filter.|
|It is more simple instrument.||It is more complex compare to colorimeter.|
|It works well for routine comparisons of similar colors and for adjustment of small color differences under constant conditions.||It works well for color formulation, measurement of metamerism and variable illuminant/observer conditions.|
|Examples of colorimeter instruments: HunterLab D25 series, ColorTrend HT||Examples of Spectrophotometer instruments: HunterLab ColorFlexes, COlorQuests, LabScans, MiniScans, SpectraProbes, UltraScans|