Evolution of the number of dots

It is a well-known rule that a color ink can only display one shade when printed on the printed matter if it is used with 100%. However, if it is decomposed into different dots with different density on the printing plate by various means, different shades can be formed on the object to be printed, and a variety of shades can be achieved.

Back to the original stone printing plate in the 1920s, it was made with a special small pen tip, dipped in black ink, and hand-painted on the printed stone into different shades to meet the requirements. Subsequently, the film was made with different dense and uneven dots. A wooden frame (sometimes called "offset") was used as a tool on the shed. The black ink was coated on it, and then embossed on the printing according to the requirements of different shades. The stone greatly improves the work efficiency at a large area. At that time, if the number of lines is about 60 lines per inch.

In the 1930s, photographic platemaking emerged, using glass screens imported from Japan to add dots to the film during photography, from the initial 100 lines, 120 lines, 133 lines to 150 lines. In 1965, the glass screen was changed to a magenta contact screen. The tolerance of the yellow filter can be used to adjust the density contrast of the continuous color separation film. After that, it was improved to a gray contact screen with different tones. It was produced by Beijing Institute of Printing Technology and Shanghai Institute of Printing Technology and supplied to the whole country. Most of it is used for offset printing with 150 lines.

In 1973, Beijing Xinhua Factory and Shanghai Yinyi Factory first introduced the German-made Haier DC-300A electronic color separation machine, which still uses a screen to embellish the network. When the DC-300B is to be introduced, the number of dot lines is slightly different, that is, the C, M, and Y versions use 150 lines, and the K version uses 225 lines at the same angle as the Y version. Until the early 1980s, the electronic color separation machine was improved from analog to digital, and the number of dot lines also progressed to 175 lines, which has remained basically unchanged in the past 20 years.

Everyone in the industry knows that the density of dots and lines is also called the thickness, which is related to the resolution and level reduction ability, and the degree of exquisiteness of the printed matter, but it must also be aimed at the corresponding conditions of printing. I remember that in 1959, in order to participate in the East Leipzig International Book Fair, the leaders of Shanghai put forward higher requirements for the plate making of the "Collection of Paintings of Shanghai Museum". It also won the only gold copy award in the plenary.

However, the so-called "Great Leap Forward" followed, and the country's printing and platemaking industry also blew up a "high network line" that did not look at the actual conditions of customers. At that time, we were competing to produce samples, from 300 lines, 500 lines, and even 800 lines, which was called the "flying satellite" in the printing industry. The production process is to first shoot the 150-line screen into a 30-inch high net, use it to reduce it to a 7.5-inch negative net, then copy it into the Yang net, and then become the original version of the 600-line screen. But at that time, the finest gold steel grit for zinc-skin printing plates was not fine enough and was mixed with pumice powder for grinding. It barely made rough samples and could not be printed on the machine. It completely violated the scientific laws of objective reality. I have also been involved in it, both ignorant and blindly obeying, just deceiving myself!

Nowadays, it has entered the period of computer plate-making. Although most of them still use 175 lines, the scanning colorimeter (or electric sub-scanning system) combined with the internal drum type laser phototypesetter of 3 600 dpi and above can produce 200 lines or even 300 lines. Lines can also be used to arrange frequency modulation networks (also known as sand mesh dots, that is, the single dot is the finest point of the 300 line, which is formed by density or evacuation, because there is no angle, so there will be no moire). Due to the current high-performance photosensitive film, high-resolution PS printing plate, highly adaptable ink, excellent performance paper, imported precision proofing machine and four-color printing machine, etc., the number of dot lines that can be accepted has been Required for more than 175 lines.

Recently, I have also seen that some fine albums printed in Shenzhen have used 200 lines, and the recent "Reference News" printed on newsprint also used 175 lines for foreign black and white photos. Therefore, we should not stand still and should increase the number of dot lines. . Although it is occasional to look back on Shanghai, it is not popular. The thought-making process should be based on the combination of subjective requirements and macroscopic possibilities. For this reason, when we encounter the production of exquisite products and the manuscript is more ideal, it seems that it is not necessary to use 300 lines at present, but the idea of ​​using 200 lines is not necessary, so it is neither aggressive nor conservative. More refined. If the CTP process is promoted in the future, it will be more adaptable.

Led Tables Feature:

1. Polyethylene (PE) is a kind of thermoplastic material, not easy to broken, suitable for long time delivery

2. Non toxic, safe for human healthy

3. Rechargeable battery and remote control

4. Multi-colors change & color selection

5. Anti UV & waterproof

6. Adopt the EPISTAR led chip to ensure the color quality and life time

7. Certificate: CE, ROHS, etc

8. Warranty: 1 year

Led Tables

Led Tables,Led Waterproof Tables,Led Outdoor Tables,Led Color Changing Tables,RGB Color Light Tables,Led Bar Tables,Led Cube Tables

KIWA ELECTRONIC (HK) INDUSTRIES CO.,LTD , https://www.kiwahk.com