Colorimeter principle, standard, operation and color spaces

I. How to choose a colorimeter?

II. Colorimeter principle

What is colorimeter? Some people may be confused. Simply put, a colorimeter is a color measurement tool used to provide color measurement and color comparison so as to varify the color quality of samples. Color meters used in different industries have different color measuring principles. Here, we will introduce two most common measuring principles.

1. D/8° colorimeter principle

Lshtec portable colorimeter adopts d/8° integrating sphere principle. To put it simply, there is a measuring aperture (incident light) on an integrating sphere. The incident light illuminates the integrating sphere and the inside of the integrating sphere undergoes reflection and refraction to make the light source uniform. The receiving hole at an angle of 8° off center axis to receive the light and make calculation by the color difference formula. The integrating sphere is the key part of the colorimeter. The color measurement accuracy has a great relationship with the integrating sphere. If the quality of the integrating sphere is not good, it will affect the service life of the color meter, which will greatly increase the maintenance cost. Therefore, the use of a high-quality integrating sphere will extend the use time of the instrument. 

2. 45°/0 colorimeter principle

The handheld color difference meter adopt the 45°/0 principle which means (45°annular illumination, 0° viewing angle). Simply put, the light source irradiates from all directions at the same time and is found to illuminate the reflective sample at a 45° angle. Our handheld color meter use four light sources, which are placed on the same horizontal plane. After repeated reflections, the light emitted by the 4 light sources will evenly shine on the measured sample.

III. Colorimeter standard

Lshtec pocket colorimeters are in compliance with the relevant international CIE standards and GB standards. The specific standards are as follows:

GBT 3978-2008 Standard illuminants and geometric conditions, this national standard specifies the relative spectral power distribution of CIE standard lighting bodies A, D65 and other luminaires C. The angle and space condition of the Lshtec 86170 colorimeter meets the condition of 45°x: o°, that is, it receives reflected radiation from a certain orientation at an angle of 45°.

GBT 3979-2008 Methods for the measurement of object color. It stipulates the technical conditions of white standards and the measurement methods of objects. The colorimeter of Lshtec is a product developed by using relative color stimulus function.

GBT 7921-2008 Uniform color space and color difference formula. In this standard, the color difference calculation and color difference color difference formulas are explained. Lshtec has just referred to these color difference formulas for color difference calculation. In addition, the two color difference meters also meet the following standards

"GBT 11186.1-1989 Methods for measuring the colour of paint films-Part 1: Principles"

"GBT 11186.2-1989 Methods for measuring the colour of paint films-Part 2: Colour measurement"

"GBT 11186.3-1989 Methods for measuring the colour of paint films-Part 3: Calculation of colour difference"

"JJG 595-2002 Colorimeters and Color Difference Meters"

IV. How to use colorimeter and colorimeter advantages

1. How to use colorimeter?

1. Both Lshtec color difference meters need to be used with colorimeter App. Let's start a color measurement using them:

2. Use the browser to scan the QR code on the instrument to install the colorimeter APP, download and install it as prompted.

3. Turn on the Bluetooth and find the SN number same as the instrument.

4. Select to calibrate the meter or skip the calibration.

5. You can choose "Color Scan" or "Color Compare".

6. Press the button on the pocket colorimeter or press the measurement button on the colorimeter App.

7. Measured color will be displayed on the screen.

2. Colorimeter advantages

1. If you make color measurement, choose the color chart you need, three closest color codes will be matched. 

2. You can establish the personal color chart and save this color. 

3. Then you can make color comparison, measure the color of the sample and use the saved color as the standard color. Two colors will be compared.

4. Lshtec colorimeter also has QC testing function, a variety of color charts are installed in colorimeter App. 

5. Seven color spaces and six color difference formulas can meet the needs of different industries. 

6. The measuring aperture of the pocket colorimeter is 8mm, which means that the surface area of the test sample only needs to be larger than the measuring aperture of 8mm. 

7. The measurement time of the instrument is very short, only 1s. 

Our portable colorimeter is small in size, compared with ordinary desktop colorimeters. Moreover, the color difference meter quality is good and the colorimeter price is relatively low compared with the colorimeter of same performance. 

V. Color spaces

7 color spaces are mainly CIE Lab, Luv, LCh, Yxy, CMYK, s-RGB, Hex, so what does Lab mean? In fact, Lab simply means the color coordinate space of a color. Any color has a unique Lab (color coordinate space). It expresses color as three values: L* for the lightness from black (0) to white (100), a* from green (−) to red (+), and b* from blue (−) to yellow (+). CIELAB was designed so that the same amount of numerical change in these values corresponds to roughly the same amount of visually perceived change. (Quoted from Wikipedia). △E represents the total color difference, △L+ means brighter and △L- means darker. △a+ means reddish, △a- means greenish. △b+ means yellowish, △b- means bluish.

In LCh, "L" means brightness, "C" means saturation and "H" means hue. Brightness, saturation and hue are the three basic attributes of color. In the RGB color space. "R" is red, "G" is green and "B" is blue. This color space is more used in the printing industry.

In the Luv color space, "L" represents the brightness and "u" and "v" represent the Chroma RGB value and the Luv value can be converted by formulas. The "Y" value in the color space Yxy represents the Y value in the tristimulus color and xy represents the chromaticity characteristics of the color. The color space CMYK represents a printing color mode. The color space HEX is also called the hexadecimal color space, which refers to the hexadecimal representation of colors.