In the printing process, the continuous blending of half-color images is achieved by the closeness of the dots. According to the CMYK four-color dot mix, it can show more tones.

First, amplitude modulation network

Amplitude-modulated network is a more common network now used. Its dot relative density is determined, according to the adjustment of the height of the dot to show the color, and then achieve the color connection. In printing, the application of amplitude modulated dot takes into account the key factors such as dot size, dot appearance, dot Angle and network line precision.

Second, dot size

The dot size is determined according to the coverage rate of the dot, also known as the ink stain rate. Generally, it is customary to use "into" as a consideration of enterprises, such as 10% coverage of the network is called "10% of the network", 20% coverage of the network is called "20% of the network" in addition, 0% coverage of the network is called "absolute network", and 100% coverage of the network is called "on-site".

The tone of printing is generally divided into three levels: light tone, middle tone, dark tone. Brightening part of the network coverage is 10% ~ 30%; The network coverage rate of the middle part is 40% ~ 60%; The dark part is 70% to 90%. The network and site parts are separately zoned.

Third, the appearance of the network

The appearance of the dot in packaging printing is not only a ring in the imagination of many people, but the style shown by the dot under the condition of 50% ink penetration rate can be divided into: square, ring, prism three kinds.

Square outlets in 50% coverage, into a flag plate. Its grain shape is sharp, and it has a strong ability to perform at the level. Suitable for the performance of wireframes, graphics and some hard tone images.

Ring dot whether in the case of light or in the middle of the tone, the middle of the dot is all separate, and a part of the dark tone can be connected. Therefore, the performance of the selected level is not good, and there is very little selection in four-color printing.

The prismatic dot integrates the soft tone characteristics of the hard tuning of the square dot and the ring dot, and the color connection is of course suitable for the performance of the general image and photo.

Fourth, network Angle

In printing, the selection of dot Angle is very important. When selecting the dot Angle of the problem, interference fringes may occur.

The common dot Angle has 90 degrees, 15 degrees, 45 degrees, 75 degrees. 45 degree dot performance is the best, smooth and do not look rigid; The Angle of 15 degrees and 75 degrees is less reliable, but the visual impact is not rigid; The Angle of 90 degrees is the most stable, but the visual impact is too rigid, there is no artistic beauty.

Two or two kinds of nodes are set together, there will be mutual intervention, when the intervention is more serious to harm the beauty of the image, it will occur alias "broken".

Generally speaking, the Angle difference between the two kinds of nodes is 30 degrees and 60 degrees, and the overall interference fringe is also very beautiful and generous; The second is 45 degree dot Angle difference; When the Angle difference between the two kinds of dots is 15 degrees and 75 degrees, the interference fringe is not conducive to the beautiful image.

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