How to use offset printing for image copying

1) Continually adjusting the film During the process of copying, the density transmission is difficult to control, and the image copy quality is difficult to guarantee.

2) Since the principle of lithography of offset printing plates is very different from the principle of silver sensitization, the printing plates that are printed out have only two states of ink and non-inking. The result of printing only has two levels, colored and non-colored, and cannot be like silver. The salt sensitization material can change the gradation by changing the density of silver particles.

3) Even if a continuous-tone plate can be developed, the offset press cannot control the density of the image through accurate ink layer thickness, thereby completing the image-level reproduction. Therefore, the continuous tone image of the original document must be invaded into its own independent dots. The density value of each dot is the same.

4) The difference in color and depth of tone, the dot area is not the same. Dark shadows, large dots, printing only need to provide the same thickness of the ink layer, the amount of ink is not, copy the product color is dark; bright tone, small dot, although the ink thickness and dark tone of each dot is the same However, due to the small dot area and the low amount of ink, the color of the copied product is light, and thus the color changes in shades of light.

: Printing China