Three Methods of Color Measurement

Color measurement is mainly divided into light source color measurement and object color measurement. Object color measurement can be divided into fluorescent object measurement and non fluorescent object measurement.

In practical production and daily life, the color measurement of non fluorescent objects is widely used. It is mainly divided into visual color measurement and instrument color measurement. Among them, instrumental color measurement includes photoelectric integration method and spectrophotometry.
1. Visual method
Visual method is a traditional color measurement method. It is a completely subjective evaluation method, but also a very simple method. It directly compares the printed matter with the standard sample manually to evaluate the color difference between the printed matter and the standard sample. At the same time, it also uses a magnifying glass to observe the shape and overprint condition of various color dots and qualitatively evaluate the adjustment value of the dots. Its essence is a visual photometric method. The principle is to use the law of additive mixing to add the unknown colors of each component together to describe the obtained unknown colors. Although the most reliable way for color evaluation is to use the human eye, and it is simple and flexible, due to the influence of the observer’s experience and psychological and physiological factors, the method has too many variable factors and cannot be described quantitatively, which affects the accuracy and reliability of the evaluation.

2. Photoelectric integration method
For a long time, density method has occupied a high position in color measurement. However, with the application of CIE1976L *, a *, b * becoming more and more popular and covering the whole workflow from prepress to printing, people are increasingly aware of the importance of chromaticity, and the rapid development of modern colorimetry has laid a foundation for the objective evaluation of color by photoelectric integrating instrument (i.e. precision colorimeter).
Photoelectric integration method is a common method used in instrument color measurement in 1960s. It is not to measure the color stimulus value of a certain wavelength, but to measure the tristimulus values X, Y, Z of the sample through integral measurement within the whole measuring wavelength range, and then calculate the chromaticity coordinates of the sample and other parameters. When such three photodetectors are used to receive light stimulus, the tristimulus values X, Y, Z of the sample can be measured with one integration. The filter must meet the Luther condition to accurately match the light detector.
The photoelectric integrating instrument can not accurately measure the tristimulus value and chromaticity coordinates of the excellent source, but can accurately measure the color difference of two color sources, so it is also called the color difference instrument. Foreign colorimeters began to be produced in large quantities in the 1960s, while China began to develop such instruments in the early 1980s. Now, LISUN had been used well with the portable colorimeter CD-320PRO.

3. Spectrophotometry
The spectrophotometer is also called spectrophotometer. It obtains the spectral reflectance of the sample at each wavelength by comparing the reflected (transmitted) light energy of the sample with the standard reflected (transmitted) light energy under the same conditions. Then, the standard observer and standard light source provided by CIE are used to calculate according to the following formula to obtain the tristimulus values X, Y, Z, and then X, Y, Z are used to calculate the chromaticity coordinate x, y according to CIEYxy, CIELAB and other formulas, CIELAB chromaticity parameter, etc.
The spectrophotometer determines the color parameters of the sample by detecting its spectral components. It can not only give the absolute values of X, Y, Z and the color difference value △ E, but also give the spectral reflectance value of the object and draw the spectral reflectance curve of the object color. Therefore, it is widely used in color matching and color analysis. With this kind of instrument, high accuracy color measurement can be achieved, photoelectric integral color measuring instruments can be calibrated, and chromaticity standards can be established. This kind of instrument was first developed in China by LISUN DSCD-920 spectrophotometer. Therefore, the spectrophotometer is the preferred instrument for color measurement.

LISUN lauched Portable Colorimeter/Chroma Meter is an innovation color measuring tool with powerful configuration to make color measurement easier and more professional; It support Bluetooth to connect with Android and ISO devices, Portable Colorimeter/Chroma Meter will take you into a new world of color management; It can be widely used to measure color value, color difference value and find similar color from color cards for printing industry, paint industry, textile industry, etc.

CD-320PRO Portable Colorimeter

Benchtop Spectrophotometer (Reflectance and Transmittance) DSCD-920 adopts 7 inches touch screen, full wavelength range, Android operate system. Illumination : reflectance D/8° and transmittance D/0°(UV included / UV excluded), high accuracy for color measurement, large storage memory, PC software, because of above advantages, it is used in laboratory for color analysis and communication

DSCD-920 Benchtop Spectrophotometer

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