Colorimetry is a technique to describe and quantify the human perception of color by focusing on the physical aspects of color. A colorimeter measures the amount of color from a given medium. Various different applications of colorimeters exist today to quantify color, ranging from laboratories to the electronic industry.
Tristimulus colorimeters are often used in the application of digital imaging. The tristimulus colorimeter measures color from light sources such as lamps, monitors and screens. By taking multiple wideband spectral energy readings along the visible spectrum, this colorimeter can profile and calibrate specific output devices. The measured quantities can approximate tristimulus values, which are the three primary colors needed to match a test color.
A densitometer measures the density of light passing through a given frame. Density can be characterized as the level of darkness in film or print. When an image is printed, the ink pigments block light naturally when deposited by the printing process. Graphics industry professionals use densitometers to help control color in the various steps of the printing process.
Spectroradiometers quantify the spectral power distribution emitted from a given light source. In other words, the spectroradiometer measures the intensity of color. Characteristically similar to spectrophotometers, spectroradiometers are used to evaluate lighting for sales within manufacturing and for quality control purposes. Other applications include confirming a customer's light source specifications and calibrating liquid crystal displays for televisions and laptops.
A spectrophotometer is an analytical tool that measures the reflection and transmittance properties of a color sample. Using functions of light wavelengths, the spectrophotometer passes a beam of light through the sample to record both absorbance and transmittance. The instrument does not require human interpretation and is much more complex than a standard colorimeter. Common applications for the spectrophotometer include color formulation and industry research and development.
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