On the AM screen print, the printed image was cloudy compared to the actual document. This is not the turbidity of the ink itself, but the turbidity felt by the moment the white paper around the ink image is reflected in the human eye. It can be seen from Fig. 6 that when dot gain occurs, compared with AM screening, FM screening increases the amount of dot gain, so it is difficult for the naked eye to feel white on the paper, and the turbidity of the color is reduced. . According to this phenomenon, the color of the ink image looks bright.

In addition, Staccato has worked on various colors of dots to reduce the overlap, thereby reducing the color turbidity caused by the reflected light from the paper white and the overlap of the ink. At the same time, the ink film is thin and the midtones are increased. Color saturation plays a role.

VII. FM screening and consumption reduction

It does not have a screen for AM screening. One of the biggest features of FM screening is the reduction in ink consumption. As mentioned earlier, AM screens are different in the size of the dots. The ink is in a viscous flow. The thickness (ink volume) of the ink film is different in the positions of large dots and small dots. Therefore, the amount of ink applied is not uniform, and the ink supply amount has to be adjusted during the printing process (toggle the ink key). On the other hand, FM screening is due to its finest ideas. There is a certain limit to the amount of ink applied. The ink film is also thin and uniform. It can be printed by supplying a minimum amount of ink, thus saving the ink consumption.

According to the printing test of Creo's official printing press, 18-34% ink-saving reports have been reported. Considering the dot gains, comparing FM overlay and AM screening as an equivalent reproduction, the image area (inked area) on the compensated plate is compared, resulting in an area difference of 10%. In fact, measuring the ink consumption on the printing press of a printing company also yielded an average saving of 15-17%.

Anyway, the printing aspect also shows a non-negligible effect from the perspective of saving ink consumption. However, this is in terms of gradation images such as photographing and equal density. If it is text or only the print low side of the field, FM and AM screening are exactly the same. Moreover, even if there are tonal images, there will be differences in the reduction effect due to the depth of the tone.

Eight. Conclusion

In the current printing world where large technological innovations are not expected, as a strategy for the differentiation of printed products, with the popularization and popularization of CTPs, it is absolutely true that the effects of FM screening should be re-evaluated. However, it is still at an early stage and there are still many issues to be solved.

The current prepress works and printing workflows are mainly based on the process of AM screening. Among them, the addition of screening to FM screening will bring many problems to be solved in color reproduction and other aspects. When these issues are solved, FM screening becomes a complete workflow. This is not only to improve FM screening software, but more importantly, to improve ink, paper, plate, fountain solution, blanket, and printing. All aspects of the machine, in the face of these problems that need to be resolved, are expected to be coordinated by the relevant manufacturers.