Sixth, network point of view
The dot angle refers to the angle between the arrangement line of the dot and the horizontal line.
The human eye's vision is most beautiful and comfortable with the 45-degree dot angle, and the image performance is also the most stable and not rigid; it feels most uncomfortable with a dot angle of 0 degrees or 90 degrees. Even if the dot line count is high, the eye can still Feeling the formation of a line of ideas and linear patterns, affecting the expression of the picture; for 15 degrees or 75 degrees of dot network, the human eye feels general.
Therefore, for monochromatic halftone prints, we certainly use 45-degree outlets.
However, multi-color mesh prints must be staggered in order to prevent the occurrence of moiré.
Based on this, the angles of color screens commonly used in the world are as follows:
(1) In the case of two-color printing, the dark color version or the main color version is used with a 45 degree screen angle, and a light color version or a sub-color version with 15 degrees.
(2) For three-color printing, the dark color version or the main color version has a 45 degree screen angle, and the other two color versions use 15 degrees and 75 degrees.
(3) For four-color printing, the main color version uses a 45 degree screen angle, the yellow version uses a 90 degree screen angle, and the other two colors use a 15 degree and 75 degree screen angle, respectively.
The reason can be analyzed from the following aspects:
(1) Judging from the color rendering properties, the yellow, magenta, cyan, and black colors have the weakest visual sensitivity in yellow, followed by magenta and cyan, and the strongest in black. Therefore, in our traditional camera screening, the black version is 45 degrees, the magenta version is 15 degrees, the cyan version is 75 degrees, and the yellow version is 90 degrees.
(2) In terms of the moiré characteristics, yellow, magenta, and cyan will produce obvious orange, red, or green moiré patterns, and moiré patterns produced by yellow and black are not obvious. Therefore, if the pattern main color is red, Set as follows: magenta version - 45 degrees; black version - 15 degrees; cyan -75 degrees; yellow version - 90 degrees; with blue as the color, then: cyan -45 degrees; black -75 degrees; magenta Edition - 15 degrees; yellow version - 90 degrees.
(3) From the point of view of original screens of original screens: If the original used is a copy of a printed matter, that is, a halftone original, the original itself has dots, and when copied, color separation and screening may cause overlap. , produces a serious moire. At this time scanning originals should first eliminate the net processing, that is to change the scanning hole, try to make it increase, to reduce the resolution, or the virtual focal length, has been transferred to the Internet point of the original text can not see clearly, or use PHOTOSHOP software Elimination network order elimination network processing once. Of course, these operation methods are effective for eliminating halftone dots on the original, but have a certain influence on the color separating and screening quality of the original and reduce the clarity of the product. If the elimination of the network is not complete, moire may still occur when printing. If the sharpness of the product is required to be high and moire is not allowed to occur, the dot angle selected for each color version at the time of copying should be offset from the dot point of the corresponding color plate on the original. Such as:
The originals are: Magenta version - 45 degrees; Black version - 15 degrees; Youth version - 75 degrees; Yellow version - 90 degrees; printing can be changed to: Yellow Edition - 45 degrees; Magenta Edition - 15 degrees; Black Edition A 75 degree; cyan version of a 90 degree or other network point of view arrangement.
Seventh, the prospect of screening technology
Through the analysis of the four elements of the outlets, the mechanism for duplicating the originals into prints in a continuous tone has been clarified. This screening technology is commonly used in the current printing industry and is a traditional screening method. It is also referred to as AM screening (AM). , Amplitude Modulation), the dot pitch is equal, the size is not equal, the screen angle is set strictly, the shade level of the picture is reproduced through the dot size, and the tune reproduction is stable. However, the prints are prone to produce moire, the screen will jump, break lines, printing overlay accuracy and other defects will affect its development prospects.
In the more than 100 years of development of modern printing technology, the screening technology has also taken a big step forward. The appearance and application of FM screening technology has brought a breeze to the printing industry.
FM (Frequence Modulation) refers to the same dot size within a unit area, and the dot pitches are not the same. The tone density of the image is reflected by the dot density of the dot. As shown in Fig. 18, the picture is an irregular array of very small pixels (about 10-20 microns in diameter), with dense dots, high picture density, sparse dots, and low picture density, which reproduces the shades of the original. . The smaller the idea is, the more it reproduces the high-quality tone, color, and sharpness. The principle of imaging is similar to that of the fine silver salt particles deposited on the film. The idea is delicate, the color is soft and the density is high. The outlets are small enough that their prints and originals can be quite realistic. Of course, the required performance of the computer is also higher. In particular, random, irregular dots completely eliminate the occurrence of moiré, and increase the latitude of overprint accuracy and the color number tolerance of overprint colors, enabling high-fidelity special printing effects that are difficult to achieve with conventional four-color overprinting. .
The dot angle refers to the angle between the arrangement line of the dot and the horizontal line.
The human eye's vision is most beautiful and comfortable with the 45-degree dot angle, and the image performance is also the most stable and not rigid; it feels most uncomfortable with a dot angle of 0 degrees or 90 degrees. Even if the dot line count is high, the eye can still Feeling the formation of a line of ideas and linear patterns, affecting the expression of the picture; for 15 degrees or 75 degrees of dot network, the human eye feels general.
Therefore, for monochromatic halftone prints, we certainly use 45-degree outlets.
However, multi-color mesh prints must be staggered in order to prevent the occurrence of moiré.
Based on this, the angles of color screens commonly used in the world are as follows:
(1) In the case of two-color printing, the dark color version or the main color version is used with a 45 degree screen angle, and a light color version or a sub-color version with 15 degrees.
(2) For three-color printing, the dark color version or the main color version has a 45 degree screen angle, and the other two color versions use 15 degrees and 75 degrees.
(3) For four-color printing, the main color version uses a 45 degree screen angle, the yellow version uses a 90 degree screen angle, and the other two colors use a 15 degree and 75 degree screen angle, respectively.
The reason can be analyzed from the following aspects:
(1) Judging from the color rendering properties, the yellow, magenta, cyan, and black colors have the weakest visual sensitivity in yellow, followed by magenta and cyan, and the strongest in black. Therefore, in our traditional camera screening, the black version is 45 degrees, the magenta version is 15 degrees, the cyan version is 75 degrees, and the yellow version is 90 degrees.
(2) In terms of the moiré characteristics, yellow, magenta, and cyan will produce obvious orange, red, or green moiré patterns, and moiré patterns produced by yellow and black are not obvious. Therefore, if the pattern main color is red, Set as follows: magenta version - 45 degrees; black version - 15 degrees; cyan -75 degrees; yellow version - 90 degrees; with blue as the color, then: cyan -45 degrees; black -75 degrees; magenta Edition - 15 degrees; yellow version - 90 degrees.
(3) From the point of view of original screens of original screens: If the original used is a copy of a printed matter, that is, a halftone original, the original itself has dots, and when copied, color separation and screening may cause overlap. , produces a serious moire. At this time scanning originals should first eliminate the net processing, that is to change the scanning hole, try to make it increase, to reduce the resolution, or the virtual focal length, has been transferred to the Internet point of the original text can not see clearly, or use PHOTOSHOP software Elimination network order elimination network processing once. Of course, these operation methods are effective for eliminating halftone dots on the original, but have a certain influence on the color separating and screening quality of the original and reduce the clarity of the product. If the elimination of the network is not complete, moire may still occur when printing. If the sharpness of the product is required to be high and moire is not allowed to occur, the dot angle selected for each color version at the time of copying should be offset from the dot point of the corresponding color plate on the original. Such as:
The originals are: Magenta version - 45 degrees; Black version - 15 degrees; Youth version - 75 degrees; Yellow version - 90 degrees; printing can be changed to: Yellow Edition - 45 degrees; Magenta Edition - 15 degrees; Black Edition A 75 degree; cyan version of a 90 degree or other network point of view arrangement.
Seventh, the prospect of screening technology
Through the analysis of the four elements of the outlets, the mechanism for duplicating the originals into prints in a continuous tone has been clarified. This screening technology is commonly used in the current printing industry and is a traditional screening method. It is also referred to as AM screening (AM). , Amplitude Modulation), the dot pitch is equal, the size is not equal, the screen angle is set strictly, the shade level of the picture is reproduced through the dot size, and the tune reproduction is stable. However, the prints are prone to produce moire, the screen will jump, break lines, printing overlay accuracy and other defects will affect its development prospects.
In the more than 100 years of development of modern printing technology, the screening technology has also taken a big step forward. The appearance and application of FM screening technology has brought a breeze to the printing industry.
FM (Frequence Modulation) refers to the same dot size within a unit area, and the dot pitches are not the same. The tone density of the image is reflected by the dot density of the dot. As shown in Fig. 18, the picture is an irregular array of very small pixels (about 10-20 microns in diameter), with dense dots, high picture density, sparse dots, and low picture density, which reproduces the shades of the original. . The smaller the idea is, the more it reproduces the high-quality tone, color, and sharpness. The principle of imaging is similar to that of the fine silver salt particles deposited on the film. The idea is delicate, the color is soft and the density is high. The outlets are small enough that their prints and originals can be quite realistic. Of course, the required performance of the computer is also higher. In particular, random, irregular dots completely eliminate the occurrence of moiré, and increase the latitude of overprint accuracy and the color number tolerance of overprint colors, enabling high-fidelity special printing effects that are difficult to achieve with conventional four-color overprinting. .
Figure 18
However, due to the small size of the FM screening network, only 10-20 micrometers, which is equivalent to 1%-2% of the 175-line AM screening products, it is extremely easy to lose in copying, printing, and printing. The network of FM network is easy to expand, generally between 20% and 40%. Therefore, the printing of FM network products has high requirements for printing operations, processes, equipment, materials, technologies, and environmental temperature and humidity.
Of course, the development of printing technology will increasingly adapt to the printing requirements of FM network products. Such as:
(1) The waterless offset printing technology greatly reduces the dot gain rate and can reproduce finer dots and higher ink density.
(2) CTP direct plate-making technology and digital printing technology eliminate copying, printing and other processes, and dot-to-dot transfer is more direct and less distortion.
(3) The application of high quality equipment and materials can adapt to higher requirements for printing.
Source: Printed in China
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NINGBO YINZHOU E-RUNTE DIGITAL TECHNOLOGY CO.,LTD , http://www.firstprinters.com