Printing Screening Process Talk - FM Networking (1)

Fourth, FM screening

In the FM screening technology, all halftone micro dots have very small and the same size, each dot is as small as a single element of the recording device, and is the smallest point that a graphic recorder or printer can generate, but the image has a unit area. The average number (or frequency) varies depending on the copy tone value.

In addition, their spatial distribution is carefully assigned by an algorithm, and the points are distributed according to the statistical estimates of hue and the details of the neighboring parts of the image, without significant accumulation or accumulation of unwanted micro-points. In fact, the dot position is based on "calculated randomness."

FM screening has improved the traditional lithography process in two major ways. It uses smaller printing dots to create more detail in the image, increasing tonal range and contrast at higher ink densities. FM screening is also called "random screening" and is often called "FM screening." Although this concept was proposed many years ago, it was not until 1993 that lithographers could get their commercialized products.

1. FM screening features

(1) Advantages

1 The image looks smoother and shows more detail;

2 The image file size is 25% of the regular screening file;

3 will not appear screen moire;

4 faster on the printing press without adjustment;

5 easier to maintain the ink and water balance;

6 thicker ink coverage can get a higher dynamic range.

7 Short drying time;

8 More uniform ink distribution in thinner layers;

9 registration problems do not affect the color balance;

10 monetized spot colors and overtones of the original color version will not appear moiré;

â–  Eliminates tone jumps in midtones.

(2) Insufficient

1 has a grainy appearance, especially in the highlight part and the tone of about 25%;

2 The latitude of the entire production process is reduced, requiring more detailed process control and monitoring than the amplitude modulation and screening;

3 At present, it is difficult for the FM network image to be difficult to proof, difficult to copy, and difficult to print, which greatly hampers the combination of the film;

4 The degree of latitude for FM screening deviation is small, and many changes in film and development processing have no significant effect on the final result. Users will have to adopt new accuracy levels throughout the production process. RIP processing is noteworthy, although RIP accelerators and smaller image files have reduced their impact;

5 Because the effect of increasing the ink film thickness on the size of the FM network is not as significant as that of the amplitude modulation network, it is difficult to improve the quality of the image with poor color separation by adjusting the ink on the printing press.

6 The smallest micro-dot size is too small for many printers to reproduce correctly.

It is very simple. In the traditional AM screening method, the distance between the dots is the same and the dot size is different. The FM screening changes the distance between the center of the dot and the dot size according to the brightness and blackness of the input pixels.

Different FM network points, different network distances

Different FM network point size, the same network distance

Due to the reduction of the ink overprinting rate and the spread of the ink to other parts of the page (smaller gaps between the dots), the printing dots are rarely stained by the ink overprinting, and the non-printing area is relatively small, which has little effect on reducing the ink purity. As a result, the image has a clean, dynamic range and its advantages are:

1 low overprint rate;

2 The distribution of non-ink areas is good;

3 The proliferation of high light areas is better;

4 The distribution of different color values ​​is more uniform;

5 less fold color

6 substrates absorb less light.

As a result, better color reproduction can be achieved with FM screen printing.

More ink can be used to further increase the print color gamut. Compared with the AM network, the ink on the paper can be up to 15% higher, and the higher ink density can make the dot enlarge and reduce. In this way, the same dot area of ​​the FM network can transfer more ink.

In the transition area from white to neutral grey, the FM network exhibits less rainbow and parallelism than the traditional screen. Larger, traditional halftone dots proportionately leave large white spaces between dots, and the added white space will distort the perceived color and reduce the color saturation. A screen with a higher number of lines leaves less space between dots, and thus reproduces more accurate colors.

Proportional offset compensation is built in to the traditional method, so it is usually not considered when using conventional screening. In the case of screening using the FM network, if the proportion imbalance is not taken into account, the ratio of the blank area to the ink area changes, which will change the calculation of the transfer curve. The appearance of a given screened area varies with the distance between screens. This phenomenon is also called the "fiar effect." (to be continued)