1.Tone reproducibility
 

Any image has light and shade changes, that is, changes in tone. The law of image tone change is different, so the content of the image is different, so the tone of the image is one of the main features of the image. When copying images, strive to accurately reproduce the tone of the original image, but because the tone of the original image often changes very rich (actually continuous change), and the actual printing cannot directly reproduce the image level of the continuous tone, and In the printing process, the actual ink, watermark material, printing method and other factors will affect the accuracy of image tone reproduction, so in practice, the tone of the image should be reproduced as much as possible.

  2.Color reproducibility

  he color of the image is also one of the most basic features of the image. In the image reproduction project, the reproduction of the image color is the most complicated. It is also affected by various aspects such as printing inks, printing materials, printing methods, and technological processes. However, it has more variable factors and is more difficult to control, but Its overall reproduction of the image is also required by the technique, so the actual reproduction should also reproduce the color of the image as much as possible.

  3.Appearance characteristics
 

The appearance characteristics of the printed image including moire, bars, graininess, water marks, ink spots, etc., will affect the uniformity of the image appearance. In the dot image, some moire patterns are normal, but when the angle of the mesh is deviated, a bad moire pattern will be produced. There are many factors that affect the graininess of the image. The smoothness of the paper and the thickness of the sand of the printing plate Both are related to the granularity of the image. From a technical point of view, in addition to moire and grain patterns, most other spots and fault patterns that cause unevenness can be eliminated.