Three Methods for Color Measurement
Color measurement is mainly divided into light source color measurement and object color measurement. The object color measurement is divided into fluorescent object measurement and non-fluorescent object measurement.
In the actual production and daily life, non-fluorescent objects color measurement is the most commonly used. It is mainly divided into two kinds visual method and instrument method. And instrument method can be separated into optoelectronic integration method and spectrophotometry.
1. Visual Method
Visual method is a traditional color measurement method. It is a completely subjective evaluation method, but also the most simple way. Although the most reliable way for color evaluation is the human eyes, it is simple and flexible, but due to the observer’s experience, psychological and physiological factors, which makes the method varies too much. And color can not be quantitatively described, thus visual method has limited on accuracy and reliability.
2.Optoelectronic Integration Method
Photoelectric integration method is the most commonly used method in instrument color measurement in the 1960s. It is not measured for a certain wavelength of the color stimulus value, but in the entire measurement of the wavelength range, measured by the integral measurement of the three stimulus values X, Y, Z, and then calculate the sample color coordinates and other parameters. With these three photodetectors receiving light stimulation, the three stimulus values X, Y, and Z of the sample can be measured with one integral. The filter needs to meet the Luther condition to accurately match the photodetector.
Photoelectric integral instrument can not accurately measure the three-way stimulus value and color coordinates, but can accurately measure the color difference between the two colors, which is also known as the color difference meter. Foreign colorimeter from the 60s of last century began mass production, and China from the early 80s of last century began to develop such equipment, and now the technical is mature. Our colorimeter CS-200 is very good for measurement.
Spectrophotometry is also called spectrophotometer, which is through the sample reflection (transmission) of the light energy and under the same conditions the standard reflection (transmission) of the light energy to be obtained at each wavelength of the spectral reflectance, and then use CIE standard observer and standard light source to calculate according to the formula, to obtain stimulus values X, Y, Z, and then calculate the color coordinates x. y, CIELAB chromaticity value and other parameters.
Spectrophotometer by detecting the spectral components of the sample to determine its color value, not only can get X, Y, Z absolute value and color difference △E, can also get the object spectral reflectance value, and color spectral reflectance curve. So it is widely used in color matching and color analysis, the use of such instruments can achieve high accuracy, calibrate the photoelectric integral color measurement equipment, establish color standards, etc. The first spectrophotometer in China is CS-600 which is researched and produced by CHNSpec. We are the leader of Chinese color measuring instruments.