Li Yongqiang talks about color reproduction of offset printing

Offset color printing adopts the principle of color color subtractive method to perform color matching to complete color reproduction. In general, if the substrate is blank, there are eight colors that appear on the surface during the color reproduction process.

Figure 1-3: Eight Colors on Prints

1. White (W): It is the true color of the paper. After visible light is incident on the paper surface, it is approximately totally reflected and forms white. (Figure 1-3/a)

2. Yellow (Y): After visible light is incident on the yellow ink layer, the ink layer absorbs blue-violet light and reflects red light and green light, that is, R+G=Y makes the human eye see yellow (Fig. 1-3/b)

3. Magenta (M): After visible light is incident on the magenta ink layer, the ink layer absorbs green light and reflects blue-violet light, that is, B+R=M makes the human eye see the magenta (M). Figure 1-3/c )

4. Cyan (C): After visible light is incident on the cyan ink layer, the ink layer absorbs red light and reflects blue-violet light and green light. That is, B+G=C makes the human eye see cyan. Figure 1-3/d

5. Red (R): After visible light is incident on the yellow and magenta superimposed ink layers, the yellow and magenta ink layers absorb blue, violet, and green light respectively, reflecting only red light, making the human eye see the red image 1-3/e.

6. Green (G): After visible light is incident on the yellow and green superimposed layers, the yellow and blue ink layers respectively absorb blue-violet light and red light, reflecting only green light. Make the human eye see the green figure 1-3/f

7. Blue-violet (B): After visible light is incident on the magenta and cyan ink layers, the magenta and cyan ink layers absorb green and red light, respectively, reflecting blue-violet light, allowing the human eye to see blue-violet. Figure 1-3/g

8. Black (BK): After visible light is incident on the yellow, magenta, and cyan ink layers, it is approximately absorbed and the human eye sees black. Figure 1-3/h

Tip: Usually in color science, black is represented by the English letter K.

The above-mentioned eight colors of W, Y, M, C, R, G, B, and K are typical color subtracting processes, that is, the reflected light energy is continuously reduced as the ink stack color increases. Therefore, the colors appear darker and darker. For offset printer operators, it is essential to master the eight colors of prints. However, to make the print more colorful, this depends on the dot color.