Techniques and essentials for gravure image color processing

Techniques and essentials for gravure image color processing

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The color of commodity packaging is the key to the sales of goods, and it is the form of product content, technology and use. Therefore, it is the top priority of gravure plate making process to deal with the color of commodity packaging. Color is a complicated problem. The cost of color control in various plate-making companies has been difficult to reduce. The color problem causes a lot of waste and loss in manpower, material resources and time.

Of course, the problem is multifaceted, but one of the main reasons is that due to the profound changes in the pre-press prepress image processing in China, the customer's manuscript, high-quality color reversal film for scanning, photos and other manuscripts are getting less and less. More than 90% of the electronic image files produced by advertising design companies are mainly MO discs (magnetic, optical discs), most of them have poor picture quality, various physical colors and original physical colors and customer-provided colors. The color of the draft is very different. Therefore, it is necessary for the planner to carry out careful coloring and re-creation processing, so that the color of the picture must conform to the true color of the original object and meet the various requirements of the customer, and must conform to the laws of electronic engraving and printing art, and the color of the image. Processing technology has become the key to the quality of gravure packaging. The industry calls it the first face of gravure printing companies. The leaders of many plate-making companies recognize that there is nothing that can be done to change the quality of customer originals. Only by strengthening color management and vigorously cultivating the mapper, using the high-level art foundation of the mapper, aesthetic vision and operational skills to the customer's electronic image files Technical processing and re-creation processing to compensate for defects such as poor image quality and incorrect hue to improve product quality. The author believes that the current gravure plate making company should do its best to do a good job in the system engineering management of the entire plate making process, to achieve stable gravure proofing, adjust the digital proofs, do a good job in electroplating, standardize the electric carving curve, strengthen computer production, and establish electric power points. Toning, ensuring the accurate transmission of color information and controlling the error of color information in the process of copying; on the other hand, it is necessary to cultivate more excellent coloring personnel, so that they have a certain artistic foundation, aesthetic level and scientific color, Artistic understanding, as well as methods and essentials for mastering the color processing of gravure images, as well as understanding the rules of gravure plate making and printing process, combining color configuration rules with the characteristics of commodity packaging products and printing suitability, can surpass customer expectations. Make quality products.

The following is a brief introduction of the techniques, methods and essentials of gravure image color processing researched and summarized in the gravure plate production practice for more than ten years.

First, the theory of gravure image color processing

According to the characteristics of commodity packaging products, the theory of gravure image color processing is: based on the true color of the original object, according to people's heart color processing, the original color and physical color and psychological color coordination Make a perfect copy in unison. Specifically: based on the color of the original (magnetic, optical disc), based on the true color of the original object, re-creation according to the color of people's hearts. On the one hand, we must fully loyal to the original color of the product, highlighting the attributes of the product; on the other hand, we must meet the requirements of customers, highlight the saturation of color, and emphasize the commercial effect of color.

The method should be combined with the restoration of process technology and the re-creation of heart color. The so-called reduction of art and technology, we must first make the standardization, standardization, data color management of the entire gravure plate making process, combined with software-based automated color management, to make the screen color, digital proofing color and gravure proofing color as much as possible Close to achieve the reduction accuracy of digital proofing color and gravure ink proofing color to reach 95% to 98%. And under certain printing suitability conditions, the four basic standards of gravure art (grey balance, tone setting, color correction, sharpening enhancement) are the criteria. First, the gray of standardization of electric sub-scanning is done. The balance curve and the correction color data ensure that the original is scanned after the black and white field is fixed, and the original color can be restored after the digital proofing. A special technical point must be emphasized here. "In order to finally print a good product, all the information needed for the product must be obtained from the original when scanning. This is like recording music, first microphone. It’s better, otherwise, quality can’t be discussed.” The second is the foreign electronic image file, through the adjustment of the color of the image, so that the digital proof image restores the electron to fully reflect the color of the color or the color of the color. Finally, through the electronic color draft. This is the foundation of gravure image reproduction technology, and it is also the scientific nature of gravure image color processing. It should be treated as a science.

The so-called re-creation of the color of the heart, because color is not only a physical phenomenon, but is affected by people's psychological factors. Therefore, on the basis of the above-mentioned scanning standardization and restoration, according to the color of the commodity industry, according to people's heart color, as well as the defects of the original and the requirements of the customer, the various tools of Photoshop software are used for technical processing and re-creation. Processing, that is, the appropriate exaggeration and rendering of color, making it better than the original, but also beyond the expectations of customers, more able to meet the requirements of people's hearts. This is the artistic place of color processing of gravure image, and it is also the subtlety of color processing. It should be treated as an art. Only when the two are closely combined can we produce high quality products with high quality and high efficiency.

Second, before processing the color, clear color basis

Before the color of the print, first of all, what is the basis for the color? It is necessary to carefully read the process sheet and understand the customer's requirements for the color of the picture. It is based on the color palette of the disc and the color of the color draft. It is based on the reversal of the originals such as reversal films, photos, and prints, or is it only required to be adjusted to the best. Based on the specific basis, these must be made clear in advance. If the basis is not clear or based on the wrong, then the previous work will be abandoned. One reason why plate-making companies are causing many internal and external rework is that the prior color is unclear and unclear.

The second is to clarify the printability of the post-process. First, what is the substrate? Is it a film or a paper? If it is a film, it is an EOPP film, a PE film, a pearl film, a light film, a matt film, a PA nylon film, a PET polyester film, a heat sealing film, and the like. Such as paper, white paper, or kraft paper. And understand the characteristics of various paper textures such as tightness, smoothness and whiteness. The second is to understand the characteristics of the ink, is the ink in the ink, the surface of the ink is still blue, pink ink? And master the three indicators of various inks, with gray, color cast and efficiency.

The third is to clarify which printing factory the customer is. The machine of the factory is a high speed machine, a medium speed machine or a low speed machine; and grasp the printing suitability conditions and the change rules of the outlets used by the product in the factory, especially mastering the transfer What is the minimum dot value and the maximum dot value that come out. If you don't understand the printability and don't know the rules of dot change, then there is no basis for scan settings, tone, and color adjustment. It must be blind. Nowadays, one of the contradictions between many plate-making companies and printing houses is that the planners do not understand the printing suitability of the product and the changing rules of the dots, often causing the small dots to fail to transfer and the color not catching the gravure proof. Samples and mink.

Third, the steps to process the color

When dealing with color, you must first have a clear idea of the "purpose" and the approach taken to achieve this "purpose." In other words, first of all, to figure out, according to the color of the product packaging, what kind of color should be produced? Conversely, what kind of technical processing and re-creation processing should be used to produce the expected color quality, in order to ensure that the color effect in accordance with the "purpose" is produced, and the thinking and analysis must be clearly understood beforehand. There are a few. Then follow the law of color processing, adjust according to its successive steps, can not be divided into successive, what to see, what to adjust to what to think, resulting in blind, invalid repeated adjustments back and forth. Proceed as follows:

 1. Interpret the original. Before the operation, first use your own aesthetic vision and concave craft law to interpret the original, explain what the main body of the packaged product is, what are the characteristics of the commodity attribute, what are the characteristics of the physical color in the impression, and analyze and contrast the disc color What is the difference between the color scheme and the color scheme provided by the customer? Analyze the gray balance, tone level, color reproduction, sharpening degree, and whether the four basic standard data meet the printing suitability requirements of the product. What are the advantages and disadvantages? And in my mind, what is the best way to adjust it to the screen color?

In the practice, the author realized that the interpretation of the manuscript is not interpreted in advance, and the interpretation is not deep and deep. The interpretation is deep, the analysis is thorough, the imagination is high, that is, the eye is high, and then the correct method is adopted for processing; High, can make quality products quickly and well, if the eyes are not high, the hands can not rise.

  2. Color space mode conversion. At present, foreign electronic image files have two color space modes, one is the GRB mode in which GCR generates color separation; the other is that the RGB mode in which GCR generates color separation has been converted into CMYK mode, and most of them are now in this mode, two modes. Both are GCR's long-order black-and-white process. Therefore, it is necessary to convert or adjust it to meet the gravure packaging products in the three primary colors, the black version is the skeleton of the process data.

The first mode is only necessary to transfer the CMYK color separation parameters of the gravure three primary colors as the main process, which is convenient. The second mode has four conversion methods: automatic calculation method, filling method, selection tool adjustment method, and secondary conversion method. It can be selected according to the simple and complicated case of the original image.

In the mode conversion, the setting of the CMYK separation parameters is very important, it will directly affect the printing effect, and the gravure optimal setting is as follows.

3. Image sharpening. The first step in image processing is to sharpen and adjust the blur caused by the scan, which is called “corrective sharpening”, because the adjustment of the sharpening function will affect the tone value and color change. I have seen many operators sharpen the image after color correction and tone adjustment, which causes changes to the corrected color and tone values, especially the small dots of the highlight area become smaller and darker. The dot size becomes larger, and the image contrast increases. It is necessary to re-examine the highlight and dark tone values. Therefore, you should first sharpen, then make tone and color adjustment, and darken the value. Therefore, sharpening should be performed first, then tone and color adjustment, and all the tone and color changes caused by sharpening are corrected together. At the same time, after the overall tone adjustment and color correction are completed, it is necessary to make some moderate sharpening adjustment before storing the image, which is also called “target sharpening”, which is mainly necessary to compensate for the loss of clarity after printing. Degree, and compensation for the lack or excess of the first step of "corrective sharpening", adjusted to visually, the sharpness of the image is slightly overemphasized, which is extremely beneficial for maintaining the quality of the final print.

4. Gray balance adjustment. One of the keys to color image reproduction is to restore the gray in the original and correct the original color cast using the gray balance data as a criterion.

(1) Master the gravure proofing suitability and electric engraving curve of the company. The three primary color versions of Y, M and C obtained by experiment are superimposed according to the ratio of different dot areas to present neutral gray data.

(2) The focus of the gray balance adjustment is: the high-gloss white of the level is required, the white and gray tones of the 45%, 50%, and 75% parts, the gray balance ratio must be accurate, because the gray tone of these four parts is very Sensitive, with a slight error, it will be color cast.

(3) Practical experience, gray balance point value ratio, should be slightly warmer color, gray tone is slightly warmer, visually comfortable, especially white porcelain bowls, white porcelain cups and other white objects in many packaging products, slightly Warmer white and gray tones will work better.

(4) The author uses in some gravure plate making companies, the printing conditions, surface printing ink, OPP film and other suitable conditions, generally:

Highlight part: C is greater than Y, M1%; 25% part: C is greater than Y, M3%~4%; 50% part: C is greater than Y, M5%; 75% part: C is greater than Y, M4%. As shown in Table 1:

C    93   90  80   75  70  60  50  40  30  25  20  10  6  5

M   89   86  76   71  66  55  45  36  26  22  17   8   5  4

Y    89   86  76   71  66  55  45  36  36  22  17   8   5  4

5. Level adjustment. The gradation processing of the gravure image is, in theory, the printed image should have the same density range as the original. Therefore, it should be achieved that the range of tonality that can be reproduced by the gravure printing suitability is matched with the tonal range of the original, and the ever-changing manuscript tone should be adjusted to meet the requirements of the gravure engraving curve and printability. To achieve the extreme range of gravure tone; the second is to establish the "key zone" idea, that is, to pay special attention to highlighting the layered texture of the main part, adjust the color level of the various parts of the main body to the best visual brightness, adjust Handle the tone levels of the three “key areas”.

(1) Adjust and handle the level of highlights. If the high-gloss portion of the original has a large area and a rich layered texture, the first is to adjust the three primary colors of the extremely high light to 0% as the brightest part of the image; the second is to use the high-gloss white of the level to set the minimum dot value of the three primary colors. Adjust to the minimum dot value that can be transferred by printing, and adjust the ratio of the dot value to neutral white, also called the base white setting. According to the general gravure suitability, the adjustment is set to C6%, M5%, Y5%, C7%, M6%, Y6% or C8%, M7%, Y7% and the like.

(2) Adjust and handle the level of the dark tone part. If the main part of the original is processed in backlighting or dimming, the adjustment method is as follows: First, the sampling point takes the neutral black of the dark part of the image, there is no neutral black, the deepest part is taken, and the adjustment setting is C90%~93%, M86%~89 %, Y86~89%, K70%±5%, the sum of four colors is about 330%; the second is to use the black version to open the darkest part and the second deep part. Use the level curve to adjust the black version of the deepest part to 75%, the local black part to 80%, and the sub-deep level to 60%, making the dark level rich.

(3) Adjust the level of the middle part of the process. The midtone is the focus of the image. Therefore, it is important to control the midpoint (M point) because the density of the midtones is very large and shallow, and it should be adjusted to the best visual brightness. Generally, the density of the 7th ladder (M point) of the Kodak reflection ladder is 0.78, and the dot value is set to: C50%, M45%, Y45%, K5% is good, the density of the original is shallow, and should be deepened. The color density is deep and should be reduced, all of which are close to the best visual brightness.

When using the cuyve curve tool of photoshop software to adjust the tone level, two points should be noted: (1) Clearly adjust the level curve to adjust the tone level, first adjust the tone level, then adjust the color; (2) Use less level The curve tool adjusts the color, because the change of the gradation curve will affect the change of the gray system and the color system. If you want to use it, you should adjust the color to be adjusted with the lasso tool separately, or lock the local layer to make a small adjustment.

6. Color processing. Color processing is the key to the success of gravure color image copying. Since the current screen color and gravure proof color do not achieve "what you see is what you get", there are large gaps in some color gamuts, such as cyan and blue systems. Therefore, when color processing, the color of the screen cannot be used, and the inks of different characteristics such as ink, surface ink, or sky blue, pink ink, etc. used in gravure printing should be used as the basis for the color expressed on the EOPP film. Refer to the chromatogram printed by our company, the screen color as a reference, and focus on the color of the dot value data. It should be summed up in production practice, accumulate experience, find out which color gamut has the law of error, and then compensate when grading.

The standard of color processing: (1) Firstly grasp the principle of true color, that is, accurate compared with the real color; (2) Do everything possible to make the digital proofing color after coloring catch up with the color of the customer's color, and the gravure after electronic engraving Ink proofing color should catch up with digital proofing color. The accuracy of color reproduction is 95%~98%, and some color gamuts are even better than color drafting. (3) Try to meet people's heart color requirements or customer requirements for color. It is loyal to the original color of the product, and meets the requirements of people's hearts to achieve the commercial effect of color.

Use photoshop software to select the color correction tool to adjust the color should pay attention to two points: (1) should first adjust the color Y, M, C, then adjust the secondary color R, G, B; (2) do not use the color correction tool to adjust Multi-color, because the complex color belongs to the gray system, if the color correction tool is used to adjust the complex color, the total color correction is large, the color correction effect is small, and the excessive color correction will seriously affect the color system changes. To use it, adjust the color to be adjusted with the lasso tool separately.

7. Artistic processing. Artistic re-creation processing and fine processing are necessary for the production of high-quality gravure products. If there is no better than the original, there is no artistic treatment and fine processing that satisfies people's hearts, and it cannot cause emotional resonance between buyers and product manufacturers. It is not a good quality of plate making. Therefore, in order to better express the characteristics of the physical color of various commodities, on the one hand, according to people's subjective visual heart color into the operator's adjustment design, the artistic color of the picture is treated artistically, that is, moderate exaggeration The rendering, highlighting the effect of the heart, so that it meets the visual real effect perceived by the human eye; the second aspect is not simply to adjust the color saturation, but to sublimate to the normal proportion of color according to the principle of color configuration. Light and dark relationship, cold and warm relationship, highlighting the three-dimensional sense of physical shape, space sense, light and heavy feeling; three aspects to carefully repair the original particles, roads, dirty spots, unevenness and other defects, to achieve clean, smooth, delicate, refreshing and pleasing products The effect, so that people see the beautiful real color will induce the desire to buy, which requires the operator to have a higher judgment and understanding of the objective physical color, as well as master the color configuration.

In some of the plate-making companies, the author has carried out meticulous artistic re-creation processing and fine technical processing in accordance with the above three aspects, and produced many high-quality products. Not only have they been highly praised by many domestic customers and art designers, they have seen digital proofing and gravure printing. After the sample, I think that, like the effect of the idea, it is considered to be the best in the current gravure packaging products. Moreover, it has been praised by some foreign customers such as the United States and Japan, and it is considered to be comparable to their similar products. At the same time, these products are a gravure proofing success, which is really good and fast.

Fourth, the method and essentials of color processing

The process of plate making and printing of gravure-printed color packaging products is, in the final analysis, the process of color reproduction. The most fundamental of these is whether the image color processing technology of the plate-making company is excellent, whether it can bring out customer satisfaction, and can exceed customer expectations. Image color. Because the customer first looks at the color of the image is not good, the color is not bright, compared with the color draft, the color is not like, and the color that he hopes is inconsistent with the color to judge the quality of the plate making. At the same time, in the packaging art, there is often a saying that "the color is close to the flower, the color is followed by the flower, the seven-point color is three-point flower", which fully explains how important it is to handle the color of the packaged product. Therefore, from the practical application of the commercial point of view, the limit of the theory of gravure art theory and the point of satisfying the color requirements of people's hearts, combined with the color characteristics of commodity packaging products, according to the principle of color configuration, color processing according to the law of gravure art. Overcoming many current operators, they just look at the random color of the screen, blindly coloring, and sometimes the lemon color is orange, causing repeated rework. Therefore, it is important to master the 10 methods and methods of color processing.

  1. Color saturation processing. How to match the saturation is an important part of color processing, because customers require the color of their products to be saturated and even excessive. In fact, in processing, you can compress various colors or lose a certain part of color, strengthen the color of another part, and sometimes balance the saturation of all colors. You should optimize the processing according to the original content and the subject color, and master The following essentials:

1 depth basic primary color to do enough.

A variety of solid color blocks such as red, green, blue and other solid words and logos and deep basic colors that do not require gradation, the general customer requirements for these logo colors are thick, thick and vivid. Therefore, 100% of the use should be 100% in the field, in order to give full play to the extreme effect of the maximum solid density of gravure ink, can not be made 90% or 95%, although 90% or 95% of the dots will be printed Expanded to 100%, but this is not the same as 100% of the actual printing. 90% of the outlets only reach the ground in 90% of the dot area, while the expanded 5% or 10% area has ink, but the ink is thinner and the density does not reach the density in the field, so visually, 90% Or 95% of the dots are enlarged to 100% ink density is not as thick and bright as 100% of the solid density.

2 Maintain the level in the basic color of depth.

(A) The depth of the base color has a range of 65% to 90%, and more than 80% is the area where the gravure dot enlarges the most, which is easy to cause level and level.

(B) For the basic color of the area that needs to be leveled, under the premise of emphasizing the saturation of the solid color block, pay attention to maintaining the level in the basic color of the depth, and not in order to emphasize the density of the solid in the ground, and cause the depth in the basic color. Hierarchical level, can not pay attention to the level in the depth of the basic color, but affect the lack of saturation. To deal with the essentials, it is necessary to reduce the basic color of the depth required to be shallow, so as to open the distance with the density of the ground, so as to achieve the effect of the two common beauty.

3 The basic color of the middle adjustment area is sufficient.

The mid-tone zone has a set value of 35% to 65%, which is the main part of the object image and is a key area for handling good colors. It is necessary to pay attention to adjusting the basic color of the object to the optimal saturation. The essential method is to increase the color of the object by 5% or so on the basis of the amount of color required for the hue. For example, safflower, its light and medium tone M color needs 40% color, can be deepened to 45%, making the red more saturated and bright.

4 The highlights of the highlights and bright areas are sufficient.

The dot tone value of the A highlight zone ranges from 1% to 10%, and the effective tint of the gravure plate is 5% to 10%. The extremely light color of 5% or less is lost due to the transfer of the gravure small dot.

The light tone tone point value of the B bright adjustment area ranges from 10% to 35%. The highlight area and the bright area are one of the key areas of color processing.

The color quantities of the above two parts are caused by three reasons, which are caused by insufficient color. One is due to the poor transferability of the small dots in the gravure process; the other is due to the influence of the light level and the color quantity during scanning; Because the designer only cares about the contrast of the high light, the light color of the highlights and high-profile areas is seriously insufficient, and the light color of this area is the center of attention, which is often not noticed by the operators, resulting in many products being light. The hue is dull and even lost. Therefore, it is necessary to consciously deepen the basic color of the light color in this area. It should be further increased by about 5% based on the amount of color required for the color tone. For example, the light pink flower needs 10% of the M color, which should be deepened to 15 %, which makes the pale pink full. One of the key technical points here is to pull the lightest basic color away from very high light or white paper. Basic colors such as light yellow, pink, light cyan, and light green are deepened, so that the light color is full. It can also highlight highlights, which is one of the technical secrets for the quality of gravure products.

  2. The processing of color brightness. Commodity packaging products require bright and bright color, and handle the essentials:

1 To do the basic color of light, medium and deep tone, only the basic color can be done to make the color bright and beautiful. The principle is that the basic color can be sufficient but not shallow. The basic color is insufficient and the color is dim.

2 To adjust the highlight to the bright color of the bright tone, try to use the primary color or the intermediate color to make full use of the extreme effect of the purity of the three primary colors to express the brightness of the color, with or without the opposite color. Because from the theory of pigment mixing, the pigment becomes darker and darker. If the opposite color is added to the bright color of the bright tone, the color will be gray.

(A) Orange color, orange color, can not put the opposite color C version in the highlight to the bright part, if you put a little C version, orange, orange red is not bright, orange, orange layered texture by Y, M Basic color to express.

(B) Bright emerald green, the high-gloss part can't put the opposite color M version, if you put the M version, the emerald green will be gray and not bright.

(C) The color of the person's face, especially the cartoon face. The facial skin color is small. It can't be placed in the opposite color C version after the high light is adjusted to 20% of the Y and M color plates. If the C version is released, the skin color will be gray and not bright. . The specific color should start from the C color version, because the length of the character's light and dark and the Y, M color version of the dot value depends on the depth.

Of course, high-quality four-open, open calendars and posters, such as beauty photos, should be placed in the C version to fully express the color change and three-dimensionality of the skin color.

3. Processing of hue accuracy. Commodity packaging products, one is to emphasize the accuracy of the original color with the real thing, to make the color of the picture truly show the appearance and characteristics of the real thing. If the color of the object is inaccurate and the color of the tomato is orange, the copy will fail. The second is to emphasize the accuracy of copying the color and the color of the customer's color draft. Now the customer requirements are quite "demanding", and the color of each part must be consistent with the color of the color draft. If there is a slight discrepancy, it will be reworked. Therefore, we should master the following essentials:

1 First of all, the basis of the customer's request for color is clearly defined. If there is a basis, it should be based on the color of the basis. There is no basis, and only the quantity is required to be adjusted. Then, according to the true color of the objective object, the color of the heart should be re-created.

2 Many current customers are asking for the color of the color draft. Because there is a gap between the color of the screen and the color of the digital proof, it is really hard to catch up with the color of the color. The method adopted by the author is to first perform digital proofing on the electric part map or the foreign image file, and then compare and analyze the digital proof color, the screen color and the color of the customer color, what gaps exist in which color gamut, and the heart In the end, according to the color of the customer's color draft, refer to the screen color, and use the dot value data to carry out purposeful, directional, accurate coloring, so that you can take fewer detours and avoid repeating the digital sample again and again. Some have to repeat the heavy replay 6~7 times or even 10 times.

The method of color matching with dot value data: first, the dot value data of the screen color is adjusted compared with the depth of the color of the color draft; the second is to refer to the dot value data on the gravure chromatogram of various ink characteristics printed by the company. Adjustment. Be careful, fine art, meticulously catch up with the color draft, and ensure that the accuracy of the digital proofing color and the color of the customer's color draft reaches 95%~98%, so that it can be played extremely effectively.

3 Focus on the accuracy of the inherent hue, the intrinsic color is the original color of the object, to be accurately reproduced. The method is A. determining what the inherent color of the object is; B. determining the hue of the basic color of the intrinsic color; C. measuring whether the deepest primary or intermediate color of the desired level reaches 90% to 95%, and does not require hierarchy. The field is 100%; D. Determine the hue of the opposite color of the intrinsic color; E. Measure whether the opposite color of the brightest part reaches 0%.

4 It is accurate to deal with the hue of the bright and dark faces of the object. The hue of the bright face of the object is affected by the color of the light source. It is a combination of the color of the light source and the inherent color, and generally the hue and color of the light source. The hue of the dark tone surface of the object is a mixture of the intrinsic color and the ambient color. The color always has the complementary color tendency of the light source color, and the accuracy of the color of the bright and dark tone surface is processed, and the color change of the object can be expressed. The high quality of the product requires a higher aesthetic level and operational skills.

4. The principle of color master-slave principle. When adjusting the color, it is necessary to start from the whole picture, emphasizing that the color of the main part must be saturated, prominent, and the color should be light and dark, and can not be separated from the master, freely adjusted, and can not be reversed.

1 When dealing with color, it is necessary to pay attention to the relationship between the overall color and the local color. When adjusting the local color, it should be tightly integrated. When the color is set at high speed, the relationship between it and the color of the subject should be considered, and the normal proportional relationship of the color must be maintained.

2 At present, gravure plate making requires that the color of the picture is to emphasize the accuracy of the subject color. Therefore the accuracy of many electrical sub-colors. Therefore, many of the electro-optic color and the color of the foreign disk are almost always adjusted for local details. Some of the colors must be individually adjusted one by one, which often pays attention to the subordinate color and ignores the main color, thus causing color. The Lord is never divided, even the Lord. This is one aspect of the current color processing of gravure packaging products, which is simple and low-grade.

3 To analyze the main color of a picture (the color of the main match), from the relationship (the color of the effect), the general rule is: the subject color is saturated, prominent, bright, setting off the light, dark, dark Some, its role is to set off the main body, you must not adjust the color of the setting too deep, too fresh, too bright, can not be overwhelming. When dealing with the relationship between the master-slave relationship of color and the law of perspective, it should be based on the principle of master-slaveness, and dealing with the master-slave relationship of color is a must for high-quality products.

5. The treatment of color stereo. Most of the commodity packaging products use photographic originals (reverse films, photos or digital photos, etc.). To correctly handle the relationship between light, matter and shadow in the photographic photos, we must first deal with the light and dark relationship of the objects, and the light and dark of the three faces. The level is expressed, and the three-dimensionality of the object is displayed on the photo screen of the second space. It shows the three-dimensional sense of the object image, the sense of depth and the sense of space in the environment. This is one of the important technical indicators for making the gravure packaging layered. . The processing essentials are as follows:

1 Correctly handle the light and dark relationship of the object. When expressing the bright and dark parts of an object in color, it is necessary to maintain the brightness and darkness of the object when it is illuminated. With the contrast of light and dark, the subjective feeling of the object can be lifted. The first method is that the basic color should have a deep and horizontal change, and the basic tone of the middle tone cannot be darker than the dark tone. At this time, a special problem should be paid attention to. The foreign electronic image file replaces the complementary color by the GCR process, thereby causing The basic color of the dark part of the object has the defect of reversal, that is, the basic primary color of the dark part is shallower than the basic primary color of the middle part, so that the basic primary color of the dark production is insufficient, the strength is not enough, and the middle part of the object cannot be lifted. Therefore, it must be separately ticked out to deepen, enhance the three-dimensional sense of the object. Secondly, the contour of the object and the contrast between light and dark are expressed in complementary colors. Note that the complementary color of the dark part of the object cannot be too much, causing the color to be too bright and bright. Thereby losing the light and dark relationship and three-dimensionality of the object.

2 Correctly handle the relationship between the amount of color and the level of light. When adjusting the color, please note that the color quantity of the bright part cannot exceed the color quantity of the middle part, and the color of the middle part cannot exceed the color quantity of the dark part, and the relationship between the color quantity of the color and the light level is maintained. Don't just pay attention to the normal proportion relationship in which a piece of color emphasizes color and loses color, thus losing the three-dimensional sense of the object, giving a feeling of dullness and discomfort.

3 correctly handle the tone of the black version. Make full use of the outline of the black version of the object to represent the three-dimensional sense of the object, the key is to deal with the black version of the tone. On the basis of the black version of the short-ordered skeleton, the tone of the black version should be appropriately extended according to the size of the original to the middle of the adjustment to enhance the stereoscopic effect of the object.

6. The color is processed continuously in this tonality. Photographs of food, seeds and other packaged products have three major aspects, namely, bright tone, middle and dark tone, and the tones are naturally connected to each other, with continuous transitions, and the gravure art Always make a big contrast to the two ends, that is, the light is easy to be shallow, the dark tone is easy to deep, and the tone is hard and disjointed, that is, the tone of the light tone meter is lost, the tone is light, the tone is excessively leveled, and the hard mouth is not continuously excessive. Toned. Therefore, it is important to master the following processing methods.

1 First understand the relationship between each object like the three major faces, and the continuous transition of its hue, adjust the image contrast to the gravure printability range.

2A. The natural tone of the highlight and the light tone is naturally connected, and the light color of the highlight area is slightly deepened to make the light tone and the bright tone transition naturally. B. The basic color of the middle adjustment is one and the light, and the second is the tone of continuous transition.

3 The key technology to deal with the continuous transition color is the adjustment of the main color version, that is, the M color version of the warm color, the C color version of the cold color, to achieve the relationship of the three major faces, and the harmonious uniform color, giving Full color, soft and harmonious. At the same time, we must pay attention to the continuous transition tone of the black version. The key point is that when doing the gradual wind, the transition between the outlet and the net and the 75%~90% area should be natural.

7. The processing of the color jump zone.

1 Handle the color of the 80% dot jump area. According to the law of gravure engraving roller dot and OPP film proofing and printing dot increase, as the tone is deepened, there is a simultaneous increase of the dot and the depth of the cell, and the dot gain increases with the percentage ratio, and the line increases linearly. The more you go to the darker, the more you increase. The 80% area is a jump area where the dot is turned. More than 80% of the dots are linearly increased, and the color level is extremely easy to level. The increase of the dot below 80% is moderate, and the level can be printed. as shown in picture 2. Therefore, here we should pay attention to the essentials of a color processing, the deepest basic color, such as the basic color of the red color and the dark color, the dot value in the 80% ~ 85% area of the color, brown and other complex colors, The dark color of the dark tone is reduced to 80% or less, which is 75% to 78%, so as to avoid the dot jump area of 80%. As  the law.

On the one hand, it can guarantee the proofing, printing the red solid color when printing, on the other hand, it can make the dark color of the flesh-colored, brown and other complex colors neither red nor maintain the level, and achieve the best of both worlds.

2 handle the color of the 5% dot jump area. According to the rule that the engraving roller is easy to lose the small mesh point and the low-mesh transferability of the OPP film during the proofing and printing due to the high-light dimming, the small dots below 5% are generally not transferred by the machine, and the color amount affecting the high-light light hue is insufficient. And easy to be level with the extremely high light. Therefore, it is necessary to consciously deepen the basic color of the high-light tone to avoid the 5% jump point of the dot, which not only ensures the high-gloss color is full, but also makes the high-light light color tone not appear hard, disjointed, rough and ill, and is handled well. The color of the two dot jump areas is two tricks to improve the quality of the gravure color layer.