Three ways to detect the color of printed images

There are three measurement methods for printing image colors, namely densitometer measurements, colorimeter measurements, and spectrophotometer measurements.

1. Densitometer Measurement Densitometers are the main instruments for color separation, plate making and printing. This measurement method has always been the most commonly used form of objective evaluation of quality in the printing industry. Densitometers are inexpensive and widely used. When the densitometer measures the color surface, only the relative amount of a certain color ink in the printing can be obtained. It cannot indicate the hue of the measured color. Densitometer measurements are not associated with a variety of color systems and therefore cannot be described in color language. The density meter has certain limitations in color measurement and evaluation. It is not a standard color measurement instrument.

2. Colorimeter Colorimeter is a visual response that is proportional to the color tristimulus values ​​X, Y, and Z, obtained by direct measurement of the surface of the measured color. After conversion, the X, Y, and Z values ​​of the measured color are also obtained. These values ​​can be converted to other color parameters of the color space. The colorimeter is a special density meter with three broadband filters. Due to the fact that the instrument itself and the principle are thick in certain errors, the absolute accuracy of the color measurement value is not good. However, due to its low price, it is still a widely used color measuring instrument.

3. Spectrophotometer (spectrometric spectrophotometer) A colorimetric spectrophotometer measures the reflectance of light on the surface of each wavelength of the visible spectrum. The light of the visible spectrum is irradiated with the color surface at a certain step distance (5 nm, 10 nm, 20 nm), and the reflectance is measured point by point. The spectrophotometric curve of the surface of the measured color can be obtained by plotting the reflectance value of each wavelength of light with each wavelength. Each spectrophotometric curve uniquely expresses a color. The measured value can also be converted to other color system values. Spectrophotometer is a flexible, ideal color measurement instrument. At present, color measuring instruments for color quality inspection of some printing machines equipped abroad are using spectrophotometers.