The principles, characteristics, and applications of outlets. The following content is applicable to offset printing. Some of the contents may also be used as references for other types of printing. When the specific types of printing are described later, they will be explained one by one. Since this series of articles is a tutorial for designing and coloring output personnel, it is not a printed professional discussion. Some principles and algorithms are only slightly explained and not discussed in depth.
In conventional printing, dots are the basic printing units that make up a printed image, and the contrast between the image unit and the blank on the printed matter achieves the effect of reproducing a continuous tone.
The graphic information and color shades of the printed matter are formed by superimposing and overlapping different sizes of dots in the printing process to produce various hue and different brightness changes. This kind of graphic form formed by dots is called "screen" in printing, and the screen was originally a kind of "screen" used in photoengraving for a screening purpose. When used, the screen will be installed. In front of or on the surface of the photosensitive sheet, it is used to split the incident light upon photographing, and on the photosensitive sheet, dots of different sizes corresponding to the color shades of the original document are formed. The commonly used screen is a glass screen in the early stage and later becomes a contact screen. Now the new electronic color separation machine or color desktop publishing system has no screening screen.
In the AM screening method, the photoengraving method uses a conventional screen device to screen the screen. The electronic screen used by the electronic color separation machine is generally an IS (Irrational Tangent Screening) network technology developed by the German Hell Corporation (an irrational tangent network point) and an RT. (Rational Tangent Screening) Web technology (rational tangent network). Postscript screening technology is used in the color desktop publishing system.
Dots are the most basic element of the printing process. There is always a limit to the number of stages of screening, and the level change of the image cannot be infinitely changed like continuous tone adjustment. Therefore, the screening image is called a halftone image.
The outlets are the basis of the printing and copying process, and they are the basic units that make up the graphic and text. The functions of the outlets are:
1) The tasks of coloring phase, brightness and saturation in the printing effect;
2) It is the smallest unit of sensory fat and water repellent, and it is the basic element of image transmission;
3) In color synthesis is the organizer of image color, gradation, and outline.
First, the size of outlets
The traditional halftone images (usually formed by the amplitude modulation dots relative to the FM network) are arranged by the dots of different sizes and the same distance (the center point of the dot points) and form a continuous feeling visually to achieve the purpose of copying. . Among them, the regularly arranged outlets are spread outward from the center, so the number of network lines formed by outlets determines the size of a single outlet.
The dot size is determined by the coverage of the dot, also known as the ink rate. It is customary to use “cheng†as a unit of measure. For example, an outlet with 10% coverage is called a “10% outletâ€, an outlet with a 50% coverage is called a “50% outletâ€, and a 0% coverage (ie no outlet) is called For "absolute network", the coverage of 100% of the network is called "in the field."
The number of screen lines is initially defined based on the number of lines above the screen. The more lines, the finer the degree of fineness. The number of common screen lines is 80lpi, 100lpi, 120lpi, 133lpi, 150lpi, 175lpi, 200lpi. That is, the number of network cables per square inch. It is also possible to calculate the number of dots per square inch, which is equal to the square of the number of lines.
Calculate the size of the actual point of the network through an example. Suppose that the area occupied by a single network is S. Specifically, the area of ​​the network point is M, the number of screen lines is L, and the network coverage rate is n%. Then:
M=S×n%=2.54cm×2.54cm/(L×L)×n% The area unit obtained by this formula is square centimeters.
For example, the size of the tip of the 200 percent line of 200 percent is:
2.54×2.54/(200×200)×0.5=0.000080645cm2=0.0080645mm2
The dot diameter is about 0.09mm
The tone of printed matter is generally divided into three levels: bright tone, mid tone, and dark tone. The dot coverage of the highlighted part is about 1 to 3 percent; the coverage of the halftone part is about 4 to 6 percent; and the dark part is 7 to 9 percent. There are also net and field parts.
In conventional printing, dots are the basic printing units that make up a printed image, and the contrast between the image unit and the blank on the printed matter achieves the effect of reproducing a continuous tone.
The graphic information and color shades of the printed matter are formed by superimposing and overlapping different sizes of dots in the printing process to produce various hue and different brightness changes. This kind of graphic form formed by dots is called "screen" in printing, and the screen was originally a kind of "screen" used in photoengraving for a screening purpose. When used, the screen will be installed. In front of or on the surface of the photosensitive sheet, it is used to split the incident light upon photographing, and on the photosensitive sheet, dots of different sizes corresponding to the color shades of the original document are formed. The commonly used screen is a glass screen in the early stage and later becomes a contact screen. Now the new electronic color separation machine or color desktop publishing system has no screening screen.
In the AM screening method, the photoengraving method uses a conventional screen device to screen the screen. The electronic screen used by the electronic color separation machine is generally an IS (Irrational Tangent Screening) network technology developed by the German Hell Corporation (an irrational tangent network point) and an RT. (Rational Tangent Screening) Web technology (rational tangent network). Postscript screening technology is used in the color desktop publishing system.
Dots are the most basic element of the printing process. There is always a limit to the number of stages of screening, and the level change of the image cannot be infinitely changed like continuous tone adjustment. Therefore, the screening image is called a halftone image.
The outlets are the basis of the printing and copying process, and they are the basic units that make up the graphic and text. The functions of the outlets are:
1) The tasks of coloring phase, brightness and saturation in the printing effect;
2) It is the smallest unit of sensory fat and water repellent, and it is the basic element of image transmission;
3) In color synthesis is the organizer of image color, gradation, and outline.
First, the size of outlets
The traditional halftone images (usually formed by the amplitude modulation dots relative to the FM network) are arranged by the dots of different sizes and the same distance (the center point of the dot points) and form a continuous feeling visually to achieve the purpose of copying. . Among them, the regularly arranged outlets are spread outward from the center, so the number of network lines formed by outlets determines the size of a single outlet.
The dot size is determined by the coverage of the dot, also known as the ink rate. It is customary to use “cheng†as a unit of measure. For example, an outlet with 10% coverage is called a “10% outletâ€, an outlet with a 50% coverage is called a “50% outletâ€, and a 0% coverage (ie no outlet) is called For "absolute network", the coverage of 100% of the network is called "in the field."
The number of screen lines is initially defined based on the number of lines above the screen. The more lines, the finer the degree of fineness. The number of common screen lines is 80lpi, 100lpi, 120lpi, 133lpi, 150lpi, 175lpi, 200lpi. That is, the number of network cables per square inch. It is also possible to calculate the number of dots per square inch, which is equal to the square of the number of lines.
Calculate the size of the actual point of the network through an example. Suppose that the area occupied by a single network is S. Specifically, the area of ​​the network point is M, the number of screen lines is L, and the network coverage rate is n%. Then:
M=S×n%=2.54cm×2.54cm/(L×L)×n% The area unit obtained by this formula is square centimeters.
For example, the size of the tip of the 200 percent line of 200 percent is:
2.54×2.54/(200×200)×0.5=0.000080645cm2=0.0080645mm2
The dot diameter is about 0.09mm
The tone of printed matter is generally divided into three levels: bright tone, mid tone, and dark tone. The dot coverage of the highlighted part is about 1 to 3 percent; the coverage of the halftone part is about 4 to 6 percent; and the dark part is 7 to 9 percent. There are also net and field parts.
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