The improvement of print quality requires the establishment of a digital concept, so that the stability of the copy can be controlled. The measurement of gray balance is often an important basis for judging whether the copy is color cast, so the data of gray balance must improve the quality and stability of the printed matter. The data-based gray balance control law is what this institute will discuss. Gray balance is an important basis for judging copying when performing color copying. After the color is copied and measured with a densitometer, the ink amounts of the three primary colors are overprinted equally, reaching a neutral gray. Neutral gray produces a color cast, which is easy to detect because people are particularly sensitive to gray. When the original is copied, his neutral color is the same as the neutral color of the copy, so the hue balance of the color copy can be regarded as correct. Therefore, the color reproduction personnel regard the gray part as a reference basis for whether the color is overcast and the printing quality when the color is overprinted. Since the yellow, magenta, and cyan inks contain noises other than themselves, they cannot be overprinted with the same density of ink to get the density you want. Therefore, in order to prevent the printed matter from producing color casts, it is necessary to find the appropriate density of the overprinted three primary colors to achieve gray balance. In the process of color reproduction, the main control task of gray balance is to control the area of ​​the dots of the three primary colors, not the thickness of the ink. The gray printed by the three primary colors of different sizes is superimposed. Measure the gray color block in terms of concentration. When the concentration values ​​of the clear, magenta, and yellow are the same, the gray balance has been reached. Because there are many different inks in the printing plant, the dot size of the three primary colors combined by different inks may be different, not to mention the errors produced under different environments or under different needs and conditions. Factors that affect gray balance include ink volume, paper, dot area,,,,, and so on, and the balance value needs to be applied to the CIE uniform color space and color difference formula. Therefore, this paper hopes to sort out some methods for obtaining the gray balance concentration value, describe these methods in detail, and compare the advantages and disadvantages of these methods, as well as their applicable environments, and then obtain the rules of the gray balance control method. The theoretical basis is mainly to facilitate readers to understand the text, so it is divided into two points, one, noun explanation two, CIE uniform color space and color difference formula 1. Explanation of terms (1). Gray Balance After the color is copied and measured with a densitometer, the ink amounts of the three primary colors are overprinted equally, reaching a neutral gray. Generally, a black version is added during printing to increase the level of dark parts. (2). Chroma The neutral color component of the color, the higher the value, the farther away from the neutral color; the lower the value, the closer to the neutral color. (3). Colorimetry According to the human eye's visual sensing to measure color, it is a comprehensive science involving cross-research fields such as physical optics, visual physiology, visual psychology, and psychophysics. (4). CIE color system (Commission International del 'Eclairage) The stimulation of color and the sense of color are caused by the light source (source), the illuminated object (attenuator), the observer (detector), These three elements constitute the basic architecture of the CIE color system. (5). CIE standard illuminants (illuminants) Defined from the standpoint of spectral energy distribution, it may not necessarily be made into a solid light source for people to do visual color viewing and color measurement. (6). CIE standard light source (sources) The CIE standard illuminant is made into an entity to simulate its relative spectral energy to correct the CIE standard light source. 2. CIE uniform color space and color difference formula: (1). CIELAB color space: CIE uses the "1976 L * a * b * color space" referred to as CIELAB. a *: stands for the red and green coordinates, with red when positive and green when negative. (2). CIELUV color space: CIE recommends the second uniform color space, "CIE 1976 L * u * v * Color Space" for short, CIELUV. u *: Red and green coordinates, with red when positive and green when negative. v *: It is a yellow-blue coordinate with yellow when it is positive and blue when it is negative. (3) .CIELCH color space Derive other representations from CIELAB and CIELUV, called CIELCH (L * C * h °) C *: chroma h °: hue angle, representing hue (4). CIELAB color difference formula: (5) .CIELUV color difference formula: 3. Factors affecting gray balance 1. Ink volume: The inks of yellow, magenta, and cyan all contain noise other than themselves, so they cannot be overprinted with the same concentration of ink to get the density you want. This is the impurity characteristic of ink. The changes in the amount of ink will affect the density of the dot, so the amount of ink on the plate needs to be managed, and the method of managing the amount of ink is to manage the full plate density. 2. Paper: Because the surface material of the printed matter will be different, the percentage of dots on the printed matter will change, usually the dots will expand. Because light passes through paper, it is affected by four factors: (1). Absorption of ink layers (2). First surface reflectance (3). Paper reflectance (Four). Internal multiple reflection (multiple internal reflectance) 3. Full version density (Solid Ink Density-SID): The so-called full-page density refers to "the highest density of colorant on paper". That is to measure the highest density value of C, M, and Y ink with R, G, and B color filters. When the full-plate density exceeds a range, the more the dots expand, and the lower the print contrast. Will lead to a reduction in the level of the picture, will make the picture lack three-dimensional sense. Ds = -logRs Rs = 10-Ds Dr = -log (R) When printing, we need to control the full-plate density. During the printing process, if CMYK's full-plate density is not set, one of the four colors will produce a difference in density, which will be an error in the finished product. The printing factory sets a fixed set of full-color density of four primary colors, which can effectively control the gray balance. 4. Dot Area-DA (1). Film Dot Area (FDA) FDA = 1-Tt Tt: transmittance of flat mesh film Dt: integrated concentration of flat mesh film (2). Effective Dot Area-EDA EDA = FDA + (ODG + PDG) (3). Practical Dot Area-PDA PDA = FDA + PDG When making color separations, determine the appropriate dot area of ​​the three-color plate, and the appropriate dot area on the overprint differs depending on the printing conditions. ps: Urniersen equation a = PDA, Murray Davis equation a = EDA 5. Overprint: The gray parts of the three primary colors yellow, magenta, and cyan in the subtractive color method cannot match the original, and the dark portion lacks contrast. The black ink in the four-color overlapping printing can increase the density of the dark portion of the three-color overlapping printing. It is possible to reduce the cost by gray part replacement (GCR), and it is easier to achieve gray balance. However, the addition of the black version will reduce the contrast, so we should consider whether to use it according to different needs. According to different copy requirements, the black version can be divided into three types: (1) Because the density of the three primary inks is not enough, the first type black version is used to extend the maximum density of the replica (2) The first type of black plate is used as an extension, but the UCR effect is increased so that the color ink of the three primary colors can only reach a certain level; and the ink volume of the black plate is increased to replace the three primary inks of the overprinted part. (3) The full series blackboard can be divided into two forms, the difference is that the two use UCR. Six. Screen Ruling The number of dots per unit length of the printed matter, the greater the number of screen lines, the more detailed the performance of the printed matter; the smaller the number of screen lines, the opposite is true. Screens can be divided into glass screens, contact screens and screen dot film, but contact screens are the mainstream. The shape of the contact screen is divided into chain-type dots and square-type dots. Different replicas have different needs, so there are different screen lines, which can usually be distinguished as: 65.100.120.150.175.200.300 (lines / inch) lines. The quality of printing is not the greater the number of screen lines, the better, because the more detailed the screen lines, the more serious the expansion of its dots. Therefore, Mr. Zhang Haohong's master thesis "Research on Screen Line Number vs. Gray Balance" discusses the neutral balance of different screen lines in gray balance.
Aluminum Mirror is also called aluminized glass mirror, glass mirror, mirror glass, mirror plate glass. Based on the different reflective layers on the back, civilian mirrors are generally divided into aluminized glass mirrors and silver-coated glass mirrors. The aluminum mirror is the aluminum coated with the reflective layer, and its reflectivity is lower than that of the silver-coated glass mirror.
In addition, we also sell Silver Mirror glass, silver mirror commonly known as waterproof mirror, mercury mirror, silver-plated mirror on glass surface, glass mirror, mirror glass, etc. Silver mirrors are widely used in furniture, handicrafts, decoration, bathroom mirrors, cosmetic mirrors, optical mirrors, and car rearview mirrors.
Clear Aluminum Mirror,Clear Aluminum Mirror Windows,Clear Aluminum Mirror Set,Clear Aluminum Mirroring Screen Dongguan Huahui Glass Manufacturing Co.,Ltd , https://www.antiquemirrorsupplier.com
Summary
I. Introduction
2. Theoretical basis
b *: Represents the yellow-blue coordinate, with yellow when positive, and blue when negative.
L *: Lightness value, 0 is ideal black, and 10 is ideal white.
L *: Brightness.
Ds: full plate density Dr: reflectivity of full plate ink Rs: reflection density
ODG = Optical Dot Gain
PDG = Physical Dot Gain
