How to confirm the number of printing outlets

Dot angle

In printing plate making, the selection of dot angle plays an important role. Selecting the wrong dot angle will result in interference fringes.

Common dot angles are 90 degrees, 15 degrees, 45 degrees, 75 degrees. They respectively represent blue: 90 Red: 15 yellow: 45 Black: 75. 45 degree dot performance is the best, stable and does not appear rigid; 15 degree and 75 degree angle stability are worse, but the visual effect is not rigid; 90 degree angle is the most stable, but the visual effect is too rigid, there is no aesthetic feeling.

When two or more dots are nested together, there will be mutual interference. When the interference seriously affects the beauty of the image, the commonly known "moire" will appear.

Generally speaking, when the angle difference between the two kinds of dot is 30 and 60 degrees, the overall interference fringe is relatively beautiful; secondly, the angle difference between the two kinds of dot is 45 degrees; when the angle difference between the two kinds of dot is 15 and 75 degrees, the interference fringe will damage the image beauty.

dot shape

The dot shape in printing is not only the circular one as you imagine. It can be divided into three types: square, round and diamond according to the shape of dot under the condition of 50% inking rate.

Circular dots are independent in the case of bright tone or middle tone, and only in the case of dark tone can they be partially connected. Therefore, the level of performance of the poor, four-color printing is less used.

Square dot under 50% coverage, into a chessboard. Its particles are sharp, and it has a strong performance ability for levels. Suitable for lines, graphics and some hard tone image performance.

Diamond dot combines the soft tone characteristics of square dot and round dot. It has natural color transition and is suitable for general image and photo performance.

Dot line number

The size of the number of lines determines the fineness of the image, similar to the resolution. The common application of the number of lines is as follows:

Line 10-120: low quality printing, posters, posters and other large-area printing materials viewed from a long distance, usually use newsprint, offset paper for printing, and sometimes use low gram sub pink paper and copper plate paper.

Line 133: for black and white newsprint

150 lines: common four-color printing generally uses this precision, all kinds of paper have.

175-200 lines: exquisite picture albums, pictorials, etc., most of which are printed on copperplate.

250-300 line: the most demanding picture album, etc., most of which are printed on high-grade copperplate and special paper.