High-fidelity screen printing technology

In image printing, screening technology plays a decisive role in the quality of prints. In order to improve the quality of printed matter, the research on screening technology has always been an important issue in the printing industry. This includes the shape, size, angle, and combination of dots. Nowadays, high-fidelity screening technology has become a new leap in color printing. Steps of a new technology.

Screening Technology Development and Defects 1. The characteristics of AM screening are still widely used in the printing platemaking. The technology uses the mesh adjustment network to achieve continuous adjustment of the image effect. It has undergone more than 100 years of production and use, and has many advantages. However, there is also a loss of details. The screens have defects such as moiré, rose spots, and visual impingement. In particular, the moire phenomenon cannot be eradicated and increases with the increase in the number of printing plates. Therefore, it is difficult to achieve high network lines. Printing is also difficult to adapt to printing with more than four colors. One of the most basic criteria for measuring the quality of screening technology is whether it can effectively prevent the occurrence of moire. In order to make the image achieve the best color reproduction effect, although the best dot combination angle was explored in the production junior middle school to avoid the collision phenomenon to the maximum extent, it still cannot be eradicated.

2. Characteristics of FM screening Due to the defects in the AM screening technology, especially the moiré, rose spots, and gradation leap, the quality of the printed matter is affected, and it is difficult to develop printing methods with more than four colors.

For the defects of AM screening, FM screening (random screening) is studied. This screening technology uses the density of dots to represent the image hierarchy, and the distribution of dots is random. In frequency modulation screening, there is no frequency interference phenomenon, there is no problem with screen angle, and moiré and rose spots are not formed. The size of ink dots does not change the era. The only change is the frequency of outlets. Compared with traditional AM screening, printed color prints are more detailed and clearly superior to AM screen printed products under the same printing conditions. FM screening can improve the output quality of the film, and high-resolution images can be obtained with the low-resolution photo-composing machine; the print has high definition, good copying effect and good stability; it is not limited by the angle of the screen; it effectively avoids moving Network phenomenon; insensitive to overprint errors in the process of printing plate making; FM screening technology is based on the input pixel brightness and blackness to change the distance between the center point and the network size is the same, although it can avoid the defects of the AM screening technology, but it also has its own shortcomings, the main problem is the increased network The influence (periphery of the perimeter of the edge of the network increases, and the increase in the number of outlets increases). It is difficult to reproduce the dark tone level of the image, and the high-light level (skin color, etc.) tends to be rough. In addition, high requirements are imposed on materials used (such as films and plates). Low resistance to print force.

(1) Due to the equal size of the dots, there is a graininess, especially in the high-light part and the tone of about 25% is more pronounced.

(2) The latitude of the entire production process is smaller than that of the amplitude modulation screening. Therefore, a more detailed process control and monitoring technology than the amplitude modulation screening is required.

(3) The minimum dot size is too small for many printers to reproduce correctly.

(4) Since the outlets are too small, there are still some difficulties in proofing, copying, and printing.

(5) Printing plates are difficult to image and are not stable enough. As long as any change occurs in the traditional platemaking process, it will affect the final tuning of the FM plus network and reduce the reliability of screening.
3. The characteristics of hybrid screening are to make full use of the advantages of AM and FM screening to avoid the insufficiency of the two. Nowadays, AM and FM hybrid screening technologies are introduced. Hybrid screening is similar to FM screening in high-light areas and dark-tone areas. The level changes in the screen are represented by the degree of fineness of the same size and fine mesh points. The positions of the dots are randomly distributed and processed through special calculations so that the dots do not overlap each other and the dots do not become too large. In order to adapt to printing, another calculation method has been added, that is, using a plurality of small dots to form a larger printing dot. In the midtone region, the position of the dot is random, and at the same time, the size of the dot can be changed like the amplitude modulation and screening. Therefore, the midtone mesh has both the distribution characteristics of the FM mesh and the tone representation of the AM mesh.

Hybrid screening has the following features:

(1) Due to the special treatment of the positions of the highlights and shadows, the particles in this part are much less compared to the FM screening. In addition, a combination of small outlets has been calculated to improve the copy of the hospital's hip bath?BR>
(2) In the midtone region, because of the randomness of the dot position, the color skipping of the AM screening is avoided. In this meal, since the number of intermediate tone dots is fixed, the dot density per unit area can be calculated, so that the dot density of midtones can be defined. For the printing process, conventional precision production processes and equipment can be used to achieve high-line print quality without compromising bio-efficiency.

Mixed screening technology is accompanied by the CTP technology came into being, such as FAIRDOT and screens will be reached the Canadian network, which is aimed at high-precision printing and launched the mixed screening technology for CTP. As the core of CTP technology digital proofing, it also introduced its own hybrid screening proofing technology that imitation real network technology. This hybrid screening technology can not only express the color incisively, but also show the problems in the CTP process flow at a glance. Therefore, hybrid screening will be the best choice for image reproduction in the future. Combined with thermal CTP imaging technology, it can produce clearer, more replicable dot quality.

High-fidelity color for hi-fi printing before narrative high fidelity outlets. First understand high-fidelity printing. Since existing paper and ink cannot fully reproduce the color gamut of natural color originals, in order to improve the saturation of certain colors on prints, the pure, bright red color is printed on the basis of four colors of C, M, Y, and K. Colors such as green, blue and purple can create a more natural contrast and a fresher sense of color in printed images. This type of printing is called high-fidelity printing. For example, when printing a picture of strawberries, the red and green versions can be added, so that the red color of the strawberry fruit and the green color of the green leaves appear more pure and lifelike. The whole picture appears vivid and vivid.

The dot distribution in FM screening is irregular, and the distribution of silver salt particles in photographic negatives and photos is also irregular. As long as the dots in the FM screening are small enough, the printed matter can fully approach the original and achieve high fidelity. Since the frequency modulation screen is not limited by the shallow angle of the screen and the color reproduction range is wide, it can produce special printing that can not be achieved by conventional four-color separation, and can perform multi-color printing of four colors, thereby creating a high-fidelity printing effect. High-fidelity outlets are a new software standard for FM technology. It is a pure software approach. High-fidelity color using FM network, more than four-color color separation technology, in the color reproduction range, print density, clarity and level compared with the four-color screening technology has a significant development.

1. High-fidelity color technology development High-fidelity color was officially used as a noun, beginning at the Seybold Symposium (Boston, USA) in the spring of 1993. At the conference, the Davis Company opened up a gallery to present the audience with proofs printed using FM technology. This proof is called the preliminary achievement of the "high-fidelity color" scientific research project - the use of more than four colors for color printing. Up to now, there are nearly 100 companies in the world participating in this research project, including most of the international companies that have a prominent position in the prepress technology field. The goal of this project is to explore issues related to a series of theories, processes, and market trends brought about by adopting advanced technologies such as FM network points and multi-color screening. At the beginning of 1994, the color separation software launched by the Computer Research Institute of Peking University could realize the seven-color separation, which was based on the frequency modulation technology and laid the foundation for high-fidelity color platemaking technology.

2. The meaning of high-fidelity separation technology High-fidelity printing technology is relative to four-color printing technology. In four-color printing, four-color inks C, M, Y, and K are used for printing. In theory, it is sufficient to use three colors of C, M, and Y inks. However, in fact, due to various technological reasons, black ink is still needed. Also, secondary colors that are superimposed by two basic colors are not satisfactory, and secondary color spot inks must also be added. Such as M, Y two ink superimposed red than the special red ink is bright. Under this theoretical premise, high-fidelity printing was produced, that is, several spot color printings were added on the basis of four-color printing in order to expand the color expression ability of prints. The conventional color separation technology divides the colors of the original into three basic colors of cyan, magenta, and yellow, and adds black to form the range of chromatograms that the print can represent. Compared to natural colors, this range (called color coverage or umbrella cover) is much smaller. In other words, the rich colors of the natural world cannot be demonstrated with only four types of inks. The use of six-color, seven-color, eight-color high-fidelity color to produce prints, one of its purposes is to expand the scope of color reproduction, more vivid reflection of nature. Because prints with more than four colors for separation printing cannot be reproduced using conventional four-color separation technology, this technology has a special place in high value-added prints.

3. High-fidelity color-added color problems High-fidelity color can expand the color space that can be expressed in printing, thereby improving the quality of print color reproduction. One of the problems that high-fidelity color printing solves is how to properly achieve the color of the original object in the process of color reproduction, and what colors need to be added in addition to the four basic colors in order to more perfectly reproduce the original color. In general, this question does not have the same answer, because different prints have different themes and there is a difference in the color focus that needs to be expressed. According to the deficiency of traditional four-color ink performance color gamut, a multi-color printing method was proposed. However, for common and practical process requirements, there are basic choices to meet the needs of most users. For example, the basic colors used in the Kupper and Linltype-He VCF color systems are C, M, Y, K, and Orange. Green, purple, and its characteristics are in the chromatogram in the coverage of the maximum expansion as the goal, taking into account the practical aspects of production; the latter chromatogram represents a larger range than the former, through the completion of the secondary scanning color separation. The basic colors used in the Pantone 6 color system are C, M, Y, K, blue, and green. The feature is to accommodate Pantone chromatography as much as possible and reproduce Ektachrome offset printing chromatography to meet the many 6-color printing presses on the market. The basic colors used by Scitex are C, M, Y, K, red, green, and blue, which are characterized by two components of seven colors resulting from two operations of an RGB scan. The basic colors used by Crosfield Hyper Color are C, M, Y, K, C, M`, and Y`, which are characterized by the use of an ordinary 4-color machine that can be printed in two separate steps. The same color ink added can make the local relative density exceed 2.2. , to achieve the expansion of the chromatographic range. But when printing, intimate friends use transparent ink. The four-color version of the traditional four-color hard to reproduce the metal color and pearl color, high-fidelity color technology can be a good reproduction.
The market prospect of high-fidelity printing is abroad. High-fidelity printing has been applied in commercial printing. As a development direction of sheet-fed offset printing, its market prospects are promising. Such as Hexchrome high-fidelity printing is a multi-color double-sided printing process, with single-channel, multi-color printing, high profit, high production efficiency. Japan's printing technology is known for high quality and fine prints. In the field of multi-color printing, printing equipment with eight or more colors has entered the Japanese market. Most of the formats are facing, and some even reach 10 colors and 12 colors. At the same time 8-color A2 format, 6-color A3 format printing presses have also landed on the market. In addition, five-color double-sided printing presses also appeared in commercial printing, but from the perspective of cost savings, product development will focus on web printing presses.

Using high-fidelity printing will increase production costs,