Four different methods of printing plate

Hierarchical method

For black and yellow, this method is very practical. Generally speaking, in the four-color version, the black version is mostly copied in a short tone, so the level is very small and it is easy to identify; because in most of the works, the yellow components are relatively heavy, so it seems that the yellow version is full of layers. Very vague, but also relatively good recognition; and magenta version and cyan version, the level is similar, if there is no color separation experience, using this method is often easy to confuse.

Feature color discrimination

Generally experienced prepress workers use this method to differentiate. Because it meets the principle of color separation, it is highly accurate to use. We know that after color separation by the color filter, each color version has its basic color and opposite color. For magenta, the basic colors are magenta, red, blue-purple, and black, and the opposite colors are yellow, cyan, green, and white. Therefore, all red, magenta, and magenta should have a deep black color on the magenta color separation film. We can find some relevant traits, such as the red flag, the red stamp, the lips of the characters, etc. These parts should be dark in the magenta version and light in the cyan version. On the contrary, some sky, sea, forests, etc. are light-colored on magenta and dark on cyan.

Angle discrimination

This is a magnifier that looks at the separation of the film. In general, the yellow version is always 90°. This is an angle arrangement that takes into account the characteristics of the weaker version. Because magenta, cyan, and black are strong-colored versions, they must be protected from the appearance of moiré, and they are often arranged at 15°, 45°, and 75° with an angle difference of 30° from 45°.

The angle of the strong color version can be determined according to the characteristics of the original document, and there is no fixed angle. The yellow color is a weak-colored version. Even if the moiré appears, the human eye is not easy to observe. For square dots and circular dots, when the fourth ideal angle cannot be arranged in one quadrant, the worst angle gives it. Therefore, its angle is arranged at 90°. Note that since the angular arrangement of the chain points is 0° to 180°, the chain points are different.

Net flower division

If you have proofs, you can also use proofs to make a net flower division. A piece of color separation film is put on the sample sheet and slightly rotated at an angle. Some colored net flowers, namely moire, will appear in the shaded area. If a magenta net is present, the film is a magenta version; if it is a cyan net, it is a cyan version. Why is this?

We know that when the difference between the two dot angles is smaller, the bigger and more pronounced the square pattern is. When a monochrome film is placed on a proof sheet, its angle is the same as the true color of the four-color proof sheet. After the film is slightly rotated by an angle, the difference in natural colors between the film and the four-color proof sheet is small. A small angle difference is very easy to generate a clear network of flowers.

This helps us to easily identify what kind of color film is. In summary, we can sum up the quick and effective method of distinguishing different colors.