8. Handling of original color cast
At present, many manuscript images have various color casts. Therefore, the correction of ground color cast is an important content in the color adjustment operation.
(1) Color cast positioning:
First analyze whether the color of the original (including optical and magnetic disk) is discolored? The typical color cast is mainly expressed in neutral gray and the color part of the impression. When locating the color cast, one depends on the eyes; the second is to use a pipette tool to measure the dot value and the gray balance value of the company to determine whether the color is cast. Method for visually identifying color cast:
â‘ See if the black, white, and gray in the image are color shifted, because people are correct for ink, white, and gray. As long as the black, white, and gray in the picture are correct, it means that the color tone of the original is correct.
â‘¡Look at the color of the most familiar parts, such as the skin color of the characters, whether it matches the characteristics of various characters such as children's skin color, young women's skin color, actors' skin color, etc., and whether it matches the psychologically desired skin color, whether it is yellowish, red, gray, etc. defect.
â‘¢ Look at the important impression colors in the image, such as big red, green, orange, tomato, banana, walnut, strawberry, etc., whether they match the true colors of the objective real objects in the impression, and whether they match the color of the manuscript provided by the customer Match, with or without color cast.
(2) What color is determined?
â‘ Based on black, white, and gray, see which color is black, white, and gray, whether it is blue, red, or purple.
â‘¡Based on the skin color of the person's characteristics, combined with people's psychologically desired skin color, whether it is yellowish, reddish, grayish, or darker.
â‘¢Based on the true colors of objective objects, according to the requirements of customers, see what colors are important for various subjects. If the big red is more magenta, or more orange-red; if the green is more cyan, more yellowish-green, or more grayish; if orange, orange-red is more yellowish than magenta, or more magenta, yellowish, or grayish, etc., Only accurate determination of color cast, what color cast? In order to correct the deviation.
(3) Correction method:
â‘ Correction of white tone: first, if there is a layered texture in the white tone, apply the highlight tool of the gradation curve, and correct it according to the proportion of the neutral white dot value; second, if there is no layer in the white tone, you can select the white block in the color correction Tool correction.
â‘¡Middle adjustment gray correction: use the middle tool of the gradation curve to correct the deviation according to the neutral gray dot value. Two conditions should be noted:
One is to observe whether the dot value of the color cast part is close to the density value of the original. If the color dot value of the color cast part is deeper than the original density, the color version can be reduced. For example, if the gray is cold, the C version can be lightened. It not only achieves the gray balance, but also reduces the gray tone. Secondly, if the halftone value of the color cast is lighter than the original density and needs to be deepened, the opposite color can be deepened. For example, if the gray is purplish, the Y version can be deepened, which can achieve gray balance and graying.
â‘¢Ink tone correction: First, there are layers in the dark tone and black, you should use the dark tone segment tool of the gradation curve to correct the deviation according to the proportion of the neutral black dot value; Second, there is no layer in the dark tone and black tone, you can choose to adjust the color Black tools for correction.
â‘£Correction of color part: color correction, the correction of Y, M, C, R, G, and B hue using the color correction tool of Photoshop software, the correction should be based on the saturation of the color, such as green to green , Not bright, whether to add yellow or reduce cyan, if the yellow dot value has reached about 95%, and cyan is 90%, it should be reduced to 80% cyan. If the yellow is 85% and the cyan is 80%, the yellow should be deepened to 95%.
Note: when using the color correction tool to correct the deviation, it is very sensitive to the saturation color and the color correction. For the gray color, the color correction is dull. If the amount of color correction is large, it must be checked separately to adjust, otherwise it will affect the same color system. Color changes.
9. Processing of black tone
At present, copying color images of gravure packaging, how to make good use of black plates and deal with black plates is an issue to improve the quality of gravure products. The author sees that many plate-making companies have not produced many junk products because they have not processed the black plates. Many difficulties, the emergency needs to be improved. The author studied in the long-term production practice and summarized the methods and methods of dealing with black plates. After the promotion and application of some plate-making companies, the quality of the products was improved immediately, and the printing was good. It was praised by customers.
(1) Manuscripts based on color should adopt the process of mainly three primary colors, and the black version as the skeleton of short-order tone. The tone of the black version only plays the role of spiritual contour.
(2) Some of the manuscripts are mainly in bright and middle tone colors, with few grey tones and dark tones. There are no black marks on the packaging bags, so there is no black version, and the three primary colors are used. If there are black marks such as black characters, the color image can be made with three primary colors, and the black version is specially used for black characters. This solves the printing contradiction between the black in the dark part of the image and the black characters outside the image during printing. The precision and blackness of black characters can prevent dark spots from appearing in the dark part of the color image, and obtain the best of both worlds.
Processing method: the light and dark levels in the color, using complementary colors instead of the black version. Such as (A) the shadow and neck part of the character's face, the normal four-color configuration has 10% ~ 15% of the black version of the small dots, and the printed skin color appears grainy. The author takes the black version to remove 10% ~ 15% of the black The dot value of the version is copied to the green version, and the printed face shadow and neck skin color appear smooth and delicate, and the quality is significantly improved; (B) The green tone level replaces black with complementary color magenta, and the effect is excellent. For example, for the bright and middle tone of green, the original dot value is 23% for the M color version and 20% for the K version. Instead, remove the 20% K version and copy it to the M color version, that is, the M color version is 43%, so green is bright, layered and rich, and it looks delicate and not rough.
(3) Some black-based originals, such as "black sesame paste" packaging bags, use the long-order black version (GCR) process, which can make full use of the black version to express the layered texture of "black sesame paste", and It can ensure that the black color is stable and not biased during printing. The author makes a series of more than 10 kinds of "black sesame paste" packaging products in a plate-making company, using GCR long-order black adjustment process, the set value is: (A) the high-gloss part of the level, K7% ~ 8%, C4 %, M3%, Y3% (C, M, Y can not be transferred during printing, in fact, only black version of small dots, C, M, Y so put 4%, 3%, 3%, mainly for high light tone level There is a continuous transition); (B) The dark tone part, K90%, the local deepest part is 95%, C75%, M72%, Y72%, the printing effect is excellent, and the customer is quite satisfied.
(4) Due to the coarser black particles and the use of high screen lines in order to ensure the accuracy of small black characters, the dots are expanded more during printing. Generally, medium and low speed printers will have almost 80% or more than 85% levels. And paste. Therefore, the black version of the dark part of the image should be mastered in two ways: first, the black version of the dark part should be consciously pulled away; second, the amount of black cannot be adjusted too deep, preferably 70% ± 5%, so that it is away from the black characters outside the picture, so as to ensure that the black characters can be printed deep, and the dark tone of the image can maintain the level.
(5) Pay attention to the difference between the shadow black of the object and the black object. The special body shadow black means that the sub-black part cannot be deep. Keep the level. The black version of the black object can be deeper, and the local black can reach about 80%, making the black object deep and heavy . Many operators often treat the shadow black of the object as a black object, and set the black version very deep, resulting in a dark tone of the printed product.
10. Treatment of facial skin color
The facial skin color of a character is the most difficult technique to deal with in the reproduction process, because the skin color is the most sensitive, the most familiar, and the most noticeable. Even if the printed skin color is slightly color cast or slightly gray, it will produce an unpleasant feeling. Therefore, it is the crown of plate-making and printing technology pursued by plate-making companies and electronic color grading personnel to deal with the facial skin color of characters.
At present, there are two types of portrait photography manuscripts for gravure packaging products: one is cartoon portrait photos of small format and advertising portrait photos of packaging products; the second is large-size posters, calendars and other half-length photos taken by close-up shots, and their processing The essentials are as follows:
(1) Essentials for processing cartoons and portrait photos:
â‘ Guiding ideology. A. First emphasize the overall effect of skin tone, make the tone of the skin tone accurate and make it conform to the character of the character's skin tone, only need to try to catch up with the color effect of the color manuscript provided by the customer, and do not need to emphasize the color changes of various parts of the facial skin tone; Emphasize the saturated and bright skin color, that is, on the one hand, the saturation of the Y and M main color versions in the 10% to 35% region is sufficient, on the other hand, the content of the opposite color C version should be accurate, generally not below 20% of the M color version C color, to highlight the bright and bright overall skin color, refreshing and pleasing visual effects. If you want to put a little dot of the C version that can be transferred out, then the amount of Y and M colors should reach the proportion of the dot value that can suppress the C version.
â‘¡ Processing essentials. A. High-gloss skin color should be separated from extreme high-gloss and white paper. The minimum dots of the Y and M main color plates should be adjusted to the minimum dot value that can be transferred from the printing, generally the minimum is 8% ~ 10%, so that one can make the high-gloss skin complexion, and the other is to create conditions for printing out small dots . B. Dark skin color, if the main color version of Y and M is more than 80%, it must be adjusted and controlled below 80%, then it must be adjusted and controlled below 80%, and it must be separated from the red on the ground. Because first, more than 80% of the gravure dots expanded linearly; second, the dark tone of the face, neck shadows, nostrils, and dark parts of the ears of most CDs are seriously reddish, and the Y and M colors are more than 85%, and some even reach About 90%, and the C color is rare, only 5% ~ 10%, can not suppress the Y and M colors, which causes the skin color of these parts of the printed product to be seriously reddish. Therefore, the main colors of Y and M, especially the M color version, should be used to highlight the reddish parts separately, lighten to 75% ~ 78%, and deepen the C version to about 25%. This not only makes the dark part of the complexion calm and stable, but also creates favorable conditions for the printed foot prints in red. C. Adjust the skin tone to the best visual brightness. The skin tone in most compact discs has large mid-tone fluctuations, and some exposure transitions, the skin tone is light and should be adjusted for deepening. Some are underexposed and have dark skin tones, which should be adjusted for lightening and brightening, and should be close to the best visual brightness to give people a comfortable and pleasant visual effect.
(2) Handling methods for portrait photography such as posters and calendars:
This type of portrait photography is a high-end product in gravure plate-making, and it should make full use of the combination of gravure high-tech plate-making technology and art for fine processing and artistic processing.
â‘ Guiding ideology. "It should be based on the desired skin color, and the real skin color, the original skin color and the desired skin color should be harmonized and copied perfectly." Emphasize that portrait reproduction should not only reproduce the vivid character characteristics of the skin color of the portrait, but also show the skin color effect that people want in their hearts. 3. The law of light and shadow changes shows the relationship between the three-dimensional sense of the face and the warmth and coldness.
â‘¡ Master the law of color expressing facial subjective sense. Facial skin color can not be understood as a simple expression of different shades of flesh color, but there are subtle differences between parts, generally with five tones of color changes.
A. Highlight color: should be close to the color of the light source, generally a bright color of neutral white;
B. Inherent color: the most normal color of the skin itself;
C. Intermediate color: Located at the junction of the shadows, the light gradually moves to the middle of the dark part, and the hue is generally improved by the inherent color, and the lightened shadow color is also the normal color of the skin itself.
D. Shadow color: Located on the entire dark surface, the light reflected by the ambient color is the largest, and the hue is cold.
E. Reflective color: Located in the shadow, the color is affected by reflected light from nearby objects.
The above-mentioned five toned changes in the light and dark colors are the basic law of the three-dimensional expression of colors. This law tells us the following four points:
(A) The highlight color is skin color plus light source color;
(B) Shadow color is skin color plus ambient color;
(C) Reflective color is skin color plus adjacent reflection color;
(D) True skin color is expressed in intrinsic colors and intermediate colors.
In summary, all visible color levels of the face are caused by light according to different facial shapes, and it is very scientific to change the color together.
â‘¢ Master the color change law produced by the three major parts of the face.
A forehead part. The forehead is the protruding part of the face, which is a part of the face with a large area. Due to its protruding, the light is brighter, and the muscles of the forehead are less, so its color is slightly yellowish and pale yellow.
B cheek part. The cheek is the area with the largest area, and the structure is complex. Because the muscles are full here and the muscles are covered with capillaries, the color is relatively rosy and full.
C upper and lower chin part. The upper chin and lower chin belong to the flesh-colored system, because it is retracted from the forehead and cheeks, and it is in the lower part of the face. The hue is darker, which is the natural color of the skin color, and the middle color part.
The above three major parts of the Y and M color version of the dot value configuration is roughly proportional (see Table 2).
Of course, this refers to the configuration relationship of specific people in a specific environment, and then configure the appropriate C color changes, you can get a more varied skin color.
General beauty photos, children's skin color. (A) Forehead part Y> M, 2% ~ 3%, the skin color of individual pink babies and white people can also be M> Y; (B) face chin part, M> Y5% ~ 15%, so as to fully express The beauty of two red cheeks.
(C) For the chin part, the configuration ratio of Y and M is basically equal.
In summary, according to the color changes produced by the three major parts of the face, the configuration ratio of the Y and M color plates is basically this rule, which is stable. As for the specific value, it should be based on the characteristics of different characters and the color density of the original. It depends.
â‘£ Master the rule of the contrast of the three primary color versions of the high-tone facial tone. Grasping the contrast of the three primary color versions of facial highlights well, fully showing the rich color changes of highlights, is one of the key techniques for producing high-quality character skin tones. According to the laws of facial light and color changes, the contrast of the three primary colors is:
A. The Y color has the strongest contrast. Therefore, it is necessary to adjust the contrast of the Y color larger, and use the Y color to express the layered texture and color change of the highlight. Generally, the graininess of the Y color version is relatively coarse. Because the Y color is weak in color value, it is overprinted by the delicate red color, so there will be no effect.
B. The contrast of the C color is the weakest. For fine-quality facial skin color processing, a minimum dot value that can be transferred by printing should be placed in the highlight tone, because according to the principle of colored light, the stronger the light, the cooler the hue and the more blueish purple. Therefore, the C color is used to express the high-tone color changes, which adds beauty to the skin tone.
C. The brightness and contrast of the M color are between Y and C. The contrast of the highlight layer is weaker than the Y color and stronger than the C color. The processing of the M color version should be rich in layers, soft and coordinated, and fine particles.
The three primary colors of halftones for typical gravure figures are Y10%, M12%, C5% or Y13%, M15%, C6%.
Practice has proved that the highlights processed according to the contrast of the above three primary colors are extremely exciting and pleasant.
5. Judgment of the quality of electrical sub-map and color adjustment
From the screen, digital proofing proofs, gravure ink proofing proofs and printed product proofs, you can analyze and judge the quality of electrical sub-graph and color adjustment from 10 aspects.
1. First of all, from the overall hue of the screen, whether it meets the hue of the customer's sample, the hue of various objects is not correct, the saturation is not high, and there is no color cast.
2. Whether the color of the main part of the picture, especially the skin color of the characters, conforms to the true colors of objective objects and people's psychologically desired colors and the colors required by customers, whether it highlights the attributes of commodities and emphasizes the saturation of colors.
3. In the middle tone of the object, are the basic colors in the dark and high areas rich in levels, and are there any gradations? Are the basic colors in the highlight areas and the light tones areas full of light colors? There is no sense of loss and indifference.
4. Is the bright to bright color bright and bright? Is it bright? Is it saturated? Do you feel gray and stale?
5. Whether the contrast of the wind point gradation of the electrical sub-graph meets the requirements of the gravure printing process, and whether the contrast is too large or too flat. That is, whether the layered high-gloss white has a layered texture, whether there is a loss or a flat gray feeling. Does the minimum dot value of OPP film printing reach more than 5% to 7%, and is it away from the extremely high gloss and white paper? Are there any levels in the dark tone part, is there any grading phenomenon? Is the maximum dot value of the C version of the darkest part controlled at 90% ~ 93%? Is the dark flesh of the character's face red? It is controlled under 80%, whether it is separated from the deep primary colors on the ground.
6. Are the color levels of the main part of the screen rich? Is the color density set within the optimal visual brightness range? Are there any ills of being too bright or too dark.
7. Does the object's color tone, highlight to bright tone, bright tone to middle tone, and middle tone to dark tone link naturally? Does the color tone transition continuously? Are there any ills such as hard mouths or disconnections and rough particles?
8. Whether the white, gray and black in the image are accurately restored, with or without color cast or dew.
9. Whether the outline level and texture of the image are clear, and the particles are fine.
10. In the end, the whole picture is observed, and the main image is bright, the colors are bright, the layers are clear, the texture is clear, the particles are delicate, and it gives a refreshing and strong color appeal.
Vegetable Mill,Food Mill,Potato Cutter,Potato Fry Cutter
Xiongyang Household Co., Ltd , https://www.nbyjkitchen-manage.com