Colorimetry is the science that describes colors in numbers, or provides a physical color match using a variety of measurement instruments. Colorimetry is used in chemistry, and in industries such as color printing, textile manufacturing, paint manufacturing and in the food industry. The world’s first ice-calorimeter, used in the winter of 1782-83, by Antoine Lavoisier and Pierre-Simon Laplace, to determine the heat evolved in various chemical changes; calculations which were based on Joseph Black’s prior discovery of latent heat. ... Color is an important part of the visual arts. ... Chemistry - the study of atoms, made of nuclei (conglomeration of center particles) and electrons (outer particles), and the structures they form. ...

Using a colorimeter

A colorimeter is the device used in colorimetry. To use this device, different solutions must be made, and a control (usually a mixture of distilled water and another solution) is first filled into a cuvette and placed inside a colorimeter to calibrate the machine. Only after the device has been calibrated can you use it to find the densities and/or concentrations of the other solutions. You do this by repeating the calibration, except with cuvettes filled with the other solutions. A colorimeter is a device used to measure the absorbance of a specific solution. ... Distillation is a means of separating liquids through differences in their boiling points. ... A cuvette is a kind of laboratory glassware, usually a small square tube, sealed at one end, made of plastic, glass, or optical grade quartz and designed to hold samples for spectroscopic experiments. ...

Instruments

A colorimeter takes 3 wideband readings along the visible spectrum to obtain a rough estimate of a color sample. For critical color matching a spectrophotometer that takes readings 31 times along the visible spectrum would be employed. A densitometer is sufficient to measure lightness and darkness. A spectroradiometer measures the colors of light sources. A colorimeter is a device used to measure the absorbance of a specific solution. ... In physics, spectrophotometry is the quantitative study of spectra. ... Densitometer is a device that measures the degree darkness in photographic or semitransparent material. ... Spectroradiometers, (aka - spectraradiometer) which operate almost like the visible region spectrophotometers are designed to measure the spectral power distributions of illuminants in order to evaluate and catagorize lighting for sales by the manufacturer or for the customers to confirm the lamp they decided to purchase is within their specifications. ...

Range of challenges in colorimetry

Colors that look the same seldom have the same spectral characteristics in any colorimetric system you employ, even assuming identical viewing conditions and identical observers with normal color vision.

The measurement devices - in depth

Initially, the size of the filter chosen for the colorimeter is extremely important, as the wavelength of light that is transmitted by the colorimeter has to be same as that absorbed by the substance. Color can be measured using a spectrophotometer, which takes measurements in the visible region (and a little more on both ends,) of a given color sample. The spectral reflectance curve is the most accurate data that can be provided regarding a color's characteristics. However, a spectral reflectance curve is a graph of 31 readings taken at 10 nanometer increments along the electromagnetic spectrum from 400 to 700 nanometers. The plot is often referred to as the DNA of the color. However, what practical application do 31 values have? This is why the values are mathematically reduced to 3 values via a calculation that integrates the "standard observer" and your chosen light source, ending up with 3 tristimulus values, which need to be converted yet again into coordinates in the desired color space. Image File history File links No higher resolution available. ... In physics, spectrophotometry is the quantitative study of spectra. ... Spectral reflectance curves are generated by spectrophotometers. ... Legend γ = Gamma rays HX = Hard X-rays SX = Soft X-Rays EUV = Extreme ultraviolet NUV = Near ultraviolet Visible light NIR = Near infrared MIR = Moderate infrared FIR = Far infrared Radio waves EHF = Extremely high frequency (Microwaves) SHF = Super high frequency (Microwaves) UHF = Ultra high frequency VHF = Very high frequency HF = High... The amounts of red, green, and blue needed to form any particular color are called the tristimulus values and are denoted X, Y, and Z, respectively. ...

Colorimetry utilizes the standard color science calculations provided by the International Lighting Standards Commission (CIE) in 1931. Colorimetry is not an exact science due to the limitations inherent in the system (metamerism being the most troublesome), the design of the measurement devices, the values used to estimate a given light source, etc. The International Commission on Illumination (usually known as the CIE for its French-language name Commission Internationale de lEclairage) is the international authority on light, illumination, colour, and colour spaces. ... Metamerism is a psychophysical phenomenon commonly defined as the situation when two samples match in color under one condition, but fail to match under another condition. ...

See also

• Metamerism (color)
• Spectrophotometry
• spectral power distributions