Foreword: In color printing, the YMCBK four-color version is often used instead of the theoretical YMC three-primary version. Why do we need to add a black edition? Black edition is a special problem in the lithographic plate making process. It is designed to make up for the lack of density of the three primary inks in the high-density area, and it is also designed to improve the realism of the screen outline. need. As long as the four-color printing and three-color printing curves drawn in Fig. 1 are clearly compared, it can be seen from the figure that the difference between three-color printing and four-color printing lies only in the dark portion of the printed matter, since the three-color printing The dark tone density on the prints is generally insufficient. Although the human visual perception of the dark tone is higher, the dark tone level of the three-color printing is excessively compressed, which will result in the loss of the deep details of the print. The entire picture is weakened, and the density of the dark tone portion of the three-color print is insufficient. It is determined by the inherent defects of the three primary inks. Even if the three primary inks are printed in the field, they cannot print saturated black unless they are accompanied by considerable black ink. In order to make up for the lack of density in print dark spots, it is usually necessary to add a black plate and change the three-color printing to four-color printing. In general, the black version is almost indispensable for use in highlights and midtones. It is only used in the middle tone to the dark tone. This black version is the outline black version. In this way, it will not only help neutral gray balance, make the dark tone part of the printed matter darker, but also increase the contrast and details, and it can often make a finishing touch for prints.
1 Principles of the Black Edition 1.1 The reasons for using the black version and its status and role in color reproduction. Because offset printing is indirect printing, multicolor, fine mesh. There is a need for oil and water balance, and the ink itself has inherent defects of color impure, and the ink layer cannot be printed thick, otherwise the dots will have to merge. The thickness of the printing ink layer should be controlled at 1.5 ~ 2μM, the gravure printing is generally 6 ~ 8μM, the screen is at 20μM. Therefore, the three-color overprint result can make the dark tone more flat, the density not high enough, the contrast is small, and the black version can be used for compensation, so that the dark tone enhances the contrast and the dark sense of thick sense makes the level richer. The correct use of the black version in color reproduction is much better than printing a darker shade of the three primary colors with just three primary colors. Its role is: can replace some of the more expensive three primary inks with cheaper black ink, which greatly reduces costs and enhances the dark tone texture effect; can fully play the role of the black version, it not only can increase the artistic effect of the screen, but also It creates favorable conditions for high-speed multi-color printing, and stabilizes the neutral gray, so that the middle tone to dark tone can overcome the color cast.
1.2 Classification of Black Edition: Long Black Edition and Short Black Edition Long Black Edition - from high to dark tone all play a role, mainly in achromatic, and color-assisted manuscripts are long black and black. The color removal will properly subtract the ink of the three primary colors and replace it with a black one. The purpose of this black edition is to emphasize the level of the full tone. Short black version: divided into two (1) straight black version. Can increase the contrast between midtones and shadows, with a sense of thick; (2) Black outline: Start from the midtones, strengthen the midtones to the dark contrast, stabilize the level and color, can make dark and thick manuscripts Bright tone, dark tone strengthened.
1.3 The principle of the formation of the black version Previously the black version used three filter R, G, B arbitrary combinations, but difficult to control. The computer-generated black version now uses the Y, M, and C channel main signals to accurately calculate the correct black version of each pixel in which the original is scanned. The so-called correct black version - that is, the original neutral gray components can be copied to the appropriate density, the original part of the color to achieve no black version of the density. The following is a detailed introduction to the computer-generated black edition: When the computer calculates the black edition, it uses the minimum amount of three-color ink as the basic black edition. This ensures that only the composite color is used in the black edition, and the solid-colored black edition is not used; then this one is used. The numerical value (three-color minimum ink amount) minus a certain percentage of the difference between the three-color maximum ink amount and the minimum ink amount as the value for making a black plate, which takes into consideration the three-color minimum ink amount, but the composite of different solid saturations Color should have different black version (three-color ink volume is proportional to the voltage signal) as shown in Figure 2 BK = S-1 / K (LS) BK - black ink volume, L - the largest three-color ink, S - The minimum amount of ink in three colors, K - the selected scale factor. Let △ = LS, BK = S - △ / K, discuss: 1 when S = 0 is a solid color, then BK is a negative value, no black version; S> 0 is a composite color, at this time there is a black version the amount. 2 △ = LS, S is a certain case, the composite color is close to neutral gray, indicating the size of the solid color saturation of the composite color. a: △=0 L=S composite color is neutral gray, black version is the largest. b: The larger the △ is, the smaller the neutral gray component of the composite color is, and the greater the saturation is. c: Δ = LS = 0 composite color → solid color, BK = 0, so when S ≠0, △ is larger, the black version BK is smaller, only △ is larger, so that when S ≤ △ / K, BK ≤ 0 There is no black version, and the composite color is close to the solid color at this time, which is related to K selection. 3K is a constant whose size determines the degree of influence on the saturation of the composite color when it is compounded into a black plate. In color reproduction, generally K=10-15 is appropriate, because if K is large, BK=S;K Very small, △ is very small, it is close to the neutral gray, so K chooses the size of the black version that directly affects the printed matter near the solid color.
2. Under color removal and under color gain Under color removal (UCR) is to appropriately reduce the color ink in the composite color area of ​​the print, and replace it with black ink (30% to 40%). This process comes from the high speed of modern color printing. In the case of fast printing, the next color is often printed before the color of the first printing is dry. In this case, wet and dry overprinting, and the amount of ink after the printing, are large, and it is difficult to achieve the desired effect, especially in the dark. Even if the three-color ink is printed in the field, saturated black is not printed. Therefore, in production practice, instead of simply using overprinting of Y, M, and C three-color inks to reproduce the dark gray neutral components, the use of under color removal reduces the amount of three-color inks and replaces them with appropriate black inks. Figure 3 Is the limit of the removal of the background color, after the removal of the background, the amount of blue ink has been reduced to 0, magenta, yellow ink are reduced a lot, and added black ink. The effectiveness of the undercut removal process is: (1) it facilitates rapid overprinting; (2) it saves expensive color inks; and (3) when the amount of three-color inks is properly removed and the black ink is properly increased, it can also Stable neutral gray balance is conducive to the reproduction of neutral gray; (4) The computer can simply extract the neutral gray component of the dark complex color to make UCR accurate.
In the computer, the formation principle of the background color removal signal is almost the same as that of the black edition. However, when the black edition is calculated, more consideration is given to the size of the solid saturation of the parts where the original is copied. That is, the UCR is considered only in a place where the saturation of the solid color is low, and the under color removal is formed. In a place where the saturation of the solid color is large, the background removal signal is reduced as much as possible. UCR calculation formula is as follows: R = S (LK) / K R - ink removed under the background; L - the maximum value of three-color ink; S - the minimum value of three-color ink; K - proportional constant. When the UCR is not performed, the black version is often made into a short tone black version. When a certain amount of background color is removed, the black version has the complementary relationship with the background color removal. At this moment, the black version must be based on the background color removal range. Size as a variety of long tone black version. The difference between the black version and the background color removal is that the former is to compensate for the lack of dark areas, and the latter is the amount of three color inks that remove dark areas. Due to the use of black plate and background color removal, the black and gray reproductions of the system will have sufficient rich black gray, which can stabilize the neutral gray balance, while maintaining its original color in bright and bright places. Bright and bright.
Underlying Gain (UCA): The undertone gain has the opposite function to the under color removal and the same range as the UCR. It has the greatest effect on the dark part of the image and does not work on the solid part. At present, people have used computers to adjust the color shift of dark colors in the darker tone and balance the shaded color ratio. Note that the use of background color removal and background color gain cannot be used on a single color separation sheet, because this will increase the dark tone density of the first signal, and the second signal will reduce the dark tone density, so that the effect of both will be offset.
3. Non-color structure Non-color structure means that all complex colors are composed of non-color components. This non-color component is basically copied with black. The color structure process is to color any color including neutral gray and black with the three primary colors of Y, M, and C. The dark tone is very short and only serves as a skeleton to compensate for dark areas; Principle of structural replication: Black is not only used in the dark part of the diagram, but also in all the complex color structures, and plays an important role. The black version not only has a long tone, but also has a deep color and a richer level.
4, the application of the black version in the actual printing 4.1 Photo Photography:
4.1.1 The use of skeleton black edition: copy of originals in color photography, three-primary edition with long tone, cyan version can be as long as 5%-95%, yellow, magenta and cyan for color balance. Therefore, the high school tune is very full, the color is bright and thick, the entire screen as long as the shadow in the dark area to compensate for the 0.7 print density skeleton black version, the screen color can meet the visual requirements can be adapted.
4.1.2 Compensation of the black version tones after removal of the background color of the three primary colors: If the original picture of the scenery type in the above color photography is printed by a high-speed multi-color machine, the black color of the three primary colors should be removed more to reduce the dark tone. Accumulation of ink to achieve rapid drying, as for the saturated state of the deep color, the loss of the black part of the tone to make a corresponding compensation, the depth of the black version of the network point, the length of the tone, should be regarded as the three primary color background removal range and removal And set. 4.1.3 Short and long tone of black version: used in color photography to take the human skin color as the main body, and use the frontal lighting to copy pictures, in order to make the color inherent in the human skin color and the medium color to match between the net and the net. Can have a softer transition, to meet the needs of facial tone, the computer can follow the long tone black version scan, copy the starting point of the level curve can be appropriately extended; strengthen the facial dark tone level while reducing the inherent skin color to the net, and The transition to Chinese color palette promotes the black version to be extremely small at the outlets of the facial skin color area, but the level is strong and strong, the edges are not hardened, and the long tone is used as a means to make the black version achieve the purpose of both protecting and not affecting the color.
4.1.4 short-length black version of the long-term: for the face of people face the subject of the backlighting of the screen, due to the shadow of the color location, lack of photosensitivity, the color is cold with gray, should choose the skeleton black version, and enhance the dark tone , Black version of the network of the corresponding value-added, to compensate the three primary color version of the print density loss caused by the loss, strengthened the dark tone, increased the network point given value, so that the dark version of the dark tone in the enhanced steepness while reducing the The amount of tinting changes the dark backlit surface.
4.1.5 Short-cut high contrast of black print: For some color originals with high contrast density up to 3.0, when the computer is copying, the black version uses short-term high contrast, then black setpoint can be up to 85% without There are side effects, and can promote the screen to adjust the bright, dark tone, clear outline, the spirit of upright purpose.
4.1.6 The concept of the black version of black-and-white photo manuscript copy and the corresponding method of making: This kind of manuscript has clear black and white, clear levels, strong texture, and complete tones. When copying, you should break through the high-gray point gray version to put fine ideas, dark tone some black version can not exceed the old craft tradition of Bacheng's ideas, the black version of the dark tone not only deep to 90%, local dark spots even up to the field, to prevent dark when printing Concurrently paste version, the middle level of the black version can be shifted according to the conventional copying curve to make the bright points out of the net. In the case of using the gray version, the black version of the net exclusion area is slightly enlarged, and the gray version is reduced to be matched.
4.2 Artworks:
4.2.1 Chinese Painting: Chinese painting is mainly based on ink, supplemented by color, and vertical lines. The theme of the theme is expressed in ink and lines. Brightness and darkness, virtual reality and rhythm meet the vivid shape and spirit, and the vivid and creative requirements of style and spirit. When copying, you should use high-profile convex, medium-adjusting, and low-key steep copying level curves to obtain a full-scale darkening version that reflects the taste of Chinese painting.
4.2.2 The black copying curve of oil painting should be similar to the skeleton black version of color landscape photography, and the copying of oil painting should be based on the tri-color black version. It only works on the details of the secret tone, reflecting the vaguely rich color variation of the original tone.
4.2.3 When copying a gouache, the black version may be slightly longer than the oil painting, and the black version is given a darker point than the oil painting. To highlight the spirit, the black curve is used to reproduce the curve.
4.2.4 Watercolors can be ruled out by the use of three primary colors in the black version. Watercolour New Year pictures should use the skeleton black version to ensure the purity and brightness of the picture color. When copying, the tone can only be short and not long.
4.2.5 Print: The screen is dominated by strong black lines. When copying, black dots should be used. However, the given value should be deep, the tolerance should be small, the curve should be particularly steep, and the black lines should have a large background color. Remove to avoid overprinting and dark layer paste.
4.2.6 Sketch: The copy layout tone is narrow,
1 Principles of the Black Edition 1.1 The reasons for using the black version and its status and role in color reproduction. Because offset printing is indirect printing, multicolor, fine mesh. There is a need for oil and water balance, and the ink itself has inherent defects of color impure, and the ink layer cannot be printed thick, otherwise the dots will have to merge. The thickness of the printing ink layer should be controlled at 1.5 ~ 2μM, the gravure printing is generally 6 ~ 8μM, the screen is at 20μM. Therefore, the three-color overprint result can make the dark tone more flat, the density not high enough, the contrast is small, and the black version can be used for compensation, so that the dark tone enhances the contrast and the dark sense of thick sense makes the level richer. The correct use of the black version in color reproduction is much better than printing a darker shade of the three primary colors with just three primary colors. Its role is: can replace some of the more expensive three primary inks with cheaper black ink, which greatly reduces costs and enhances the dark tone texture effect; can fully play the role of the black version, it not only can increase the artistic effect of the screen, but also It creates favorable conditions for high-speed multi-color printing, and stabilizes the neutral gray, so that the middle tone to dark tone can overcome the color cast.
1.2 Classification of Black Edition: Long Black Edition and Short Black Edition Long Black Edition - from high to dark tone all play a role, mainly in achromatic, and color-assisted manuscripts are long black and black. The color removal will properly subtract the ink of the three primary colors and replace it with a black one. The purpose of this black edition is to emphasize the level of the full tone. Short black version: divided into two (1) straight black version. Can increase the contrast between midtones and shadows, with a sense of thick; (2) Black outline: Start from the midtones, strengthen the midtones to the dark contrast, stabilize the level and color, can make dark and thick manuscripts Bright tone, dark tone strengthened.
1.3 The principle of the formation of the black version Previously the black version used three filter R, G, B arbitrary combinations, but difficult to control. The computer-generated black version now uses the Y, M, and C channel main signals to accurately calculate the correct black version of each pixel in which the original is scanned. The so-called correct black version - that is, the original neutral gray components can be copied to the appropriate density, the original part of the color to achieve no black version of the density. The following is a detailed introduction to the computer-generated black edition: When the computer calculates the black edition, it uses the minimum amount of three-color ink as the basic black edition. This ensures that only the composite color is used in the black edition, and the solid-colored black edition is not used; then this one is used. The numerical value (three-color minimum ink amount) minus a certain percentage of the difference between the three-color maximum ink amount and the minimum ink amount as the value for making a black plate, which takes into consideration the three-color minimum ink amount, but the composite of different solid saturations Color should have different black version (three-color ink volume is proportional to the voltage signal) as shown in Figure 2 BK = S-1 / K (LS) BK - black ink volume, L - the largest three-color ink, S - The minimum amount of ink in three colors, K - the selected scale factor. Let △ = LS, BK = S - △ / K, discuss: 1 when S = 0 is a solid color, then BK is a negative value, no black version; S> 0 is a composite color, at this time there is a black version the amount. 2 △ = LS, S is a certain case, the composite color is close to neutral gray, indicating the size of the solid color saturation of the composite color. a: △=0 L=S composite color is neutral gray, black version is the largest. b: The larger the △ is, the smaller the neutral gray component of the composite color is, and the greater the saturation is. c: Δ = LS = 0 composite color → solid color, BK = 0, so when S ≠0, △ is larger, the black version BK is smaller, only △ is larger, so that when S ≤ △ / K, BK ≤ 0 There is no black version, and the composite color is close to the solid color at this time, which is related to K selection. 3K is a constant whose size determines the degree of influence on the saturation of the composite color when it is compounded into a black plate. In color reproduction, generally K=10-15 is appropriate, because if K is large, BK=S;K Very small, △ is very small, it is close to the neutral gray, so K chooses the size of the black version that directly affects the printed matter near the solid color.
2. Under color removal and under color gain Under color removal (UCR) is to appropriately reduce the color ink in the composite color area of ​​the print, and replace it with black ink (30% to 40%). This process comes from the high speed of modern color printing. In the case of fast printing, the next color is often printed before the color of the first printing is dry. In this case, wet and dry overprinting, and the amount of ink after the printing, are large, and it is difficult to achieve the desired effect, especially in the dark. Even if the three-color ink is printed in the field, saturated black is not printed. Therefore, in production practice, instead of simply using overprinting of Y, M, and C three-color inks to reproduce the dark gray neutral components, the use of under color removal reduces the amount of three-color inks and replaces them with appropriate black inks. Figure 3 Is the limit of the removal of the background color, after the removal of the background, the amount of blue ink has been reduced to 0, magenta, yellow ink are reduced a lot, and added black ink. The effectiveness of the undercut removal process is: (1) it facilitates rapid overprinting; (2) it saves expensive color inks; and (3) when the amount of three-color inks is properly removed and the black ink is properly increased, it can also Stable neutral gray balance is conducive to the reproduction of neutral gray; (4) The computer can simply extract the neutral gray component of the dark complex color to make UCR accurate.
In the computer, the formation principle of the background color removal signal is almost the same as that of the black edition. However, when the black edition is calculated, more consideration is given to the size of the solid saturation of the parts where the original is copied. That is, the UCR is considered only in a place where the saturation of the solid color is low, and the under color removal is formed. In a place where the saturation of the solid color is large, the background removal signal is reduced as much as possible. UCR calculation formula is as follows: R = S (LK) / K R - ink removed under the background; L - the maximum value of three-color ink; S - the minimum value of three-color ink; K - proportional constant. When the UCR is not performed, the black version is often made into a short tone black version. When a certain amount of background color is removed, the black version has the complementary relationship with the background color removal. At this moment, the black version must be based on the background color removal range. Size as a variety of long tone black version. The difference between the black version and the background color removal is that the former is to compensate for the lack of dark areas, and the latter is the amount of three color inks that remove dark areas. Due to the use of black plate and background color removal, the black and gray reproductions of the system will have sufficient rich black gray, which can stabilize the neutral gray balance, while maintaining its original color in bright and bright places. Bright and bright.
Underlying Gain (UCA): The undertone gain has the opposite function to the under color removal and the same range as the UCR. It has the greatest effect on the dark part of the image and does not work on the solid part. At present, people have used computers to adjust the color shift of dark colors in the darker tone and balance the shaded color ratio. Note that the use of background color removal and background color gain cannot be used on a single color separation sheet, because this will increase the dark tone density of the first signal, and the second signal will reduce the dark tone density, so that the effect of both will be offset.
3. Non-color structure Non-color structure means that all complex colors are composed of non-color components. This non-color component is basically copied with black. The color structure process is to color any color including neutral gray and black with the three primary colors of Y, M, and C. The dark tone is very short and only serves as a skeleton to compensate for dark areas; Principle of structural replication: Black is not only used in the dark part of the diagram, but also in all the complex color structures, and plays an important role. The black version not only has a long tone, but also has a deep color and a richer level.
4, the application of the black version in the actual printing 4.1 Photo Photography:
4.1.1 The use of skeleton black edition: copy of originals in color photography, three-primary edition with long tone, cyan version can be as long as 5%-95%, yellow, magenta and cyan for color balance. Therefore, the high school tune is very full, the color is bright and thick, the entire screen as long as the shadow in the dark area to compensate for the 0.7 print density skeleton black version, the screen color can meet the visual requirements can be adapted.
4.1.2 Compensation of the black version tones after removal of the background color of the three primary colors: If the original picture of the scenery type in the above color photography is printed by a high-speed multi-color machine, the black color of the three primary colors should be removed more to reduce the dark tone. Accumulation of ink to achieve rapid drying, as for the saturated state of the deep color, the loss of the black part of the tone to make a corresponding compensation, the depth of the black version of the network point, the length of the tone, should be regarded as the three primary color background removal range and removal And set. 4.1.3 Short and long tone of black version: used in color photography to take the human skin color as the main body, and use the frontal lighting to copy pictures, in order to make the color inherent in the human skin color and the medium color to match between the net and the net. Can have a softer transition, to meet the needs of facial tone, the computer can follow the long tone black version scan, copy the starting point of the level curve can be appropriately extended; strengthen the facial dark tone level while reducing the inherent skin color to the net, and The transition to Chinese color palette promotes the black version to be extremely small at the outlets of the facial skin color area, but the level is strong and strong, the edges are not hardened, and the long tone is used as a means to make the black version achieve the purpose of both protecting and not affecting the color.
4.1.4 short-length black version of the long-term: for the face of people face the subject of the backlighting of the screen, due to the shadow of the color location, lack of photosensitivity, the color is cold with gray, should choose the skeleton black version, and enhance the dark tone , Black version of the network of the corresponding value-added, to compensate the three primary color version of the print density loss caused by the loss, strengthened the dark tone, increased the network point given value, so that the dark version of the dark tone in the enhanced steepness while reducing the The amount of tinting changes the dark backlit surface.
4.1.5 Short-cut high contrast of black print: For some color originals with high contrast density up to 3.0, when the computer is copying, the black version uses short-term high contrast, then black setpoint can be up to 85% without There are side effects, and can promote the screen to adjust the bright, dark tone, clear outline, the spirit of upright purpose.
4.1.6 The concept of the black version of black-and-white photo manuscript copy and the corresponding method of making: This kind of manuscript has clear black and white, clear levels, strong texture, and complete tones. When copying, you should break through the high-gray point gray version to put fine ideas, dark tone some black version can not exceed the old craft tradition of Bacheng's ideas, the black version of the dark tone not only deep to 90%, local dark spots even up to the field, to prevent dark when printing Concurrently paste version, the middle level of the black version can be shifted according to the conventional copying curve to make the bright points out of the net. In the case of using the gray version, the black version of the net exclusion area is slightly enlarged, and the gray version is reduced to be matched.
4.2 Artworks:
4.2.1 Chinese Painting: Chinese painting is mainly based on ink, supplemented by color, and vertical lines. The theme of the theme is expressed in ink and lines. Brightness and darkness, virtual reality and rhythm meet the vivid shape and spirit, and the vivid and creative requirements of style and spirit. When copying, you should use high-profile convex, medium-adjusting, and low-key steep copying level curves to obtain a full-scale darkening version that reflects the taste of Chinese painting.
4.2.2 The black copying curve of oil painting should be similar to the skeleton black version of color landscape photography, and the copying of oil painting should be based on the tri-color black version. It only works on the details of the secret tone, reflecting the vaguely rich color variation of the original tone.
4.2.3 When copying a gouache, the black version may be slightly longer than the oil painting, and the black version is given a darker point than the oil painting. To highlight the spirit, the black curve is used to reproduce the curve.
4.2.4 Watercolors can be ruled out by the use of three primary colors in the black version. Watercolour New Year pictures should use the skeleton black version to ensure the purity and brightness of the picture color. When copying, the tone can only be short and not long.
4.2.5 Print: The screen is dominated by strong black lines. When copying, black dots should be used. However, the given value should be deep, the tolerance should be small, the curve should be particularly steep, and the black lines should have a large background color. Remove to avoid overprinting and dark layer paste.
4.2.6 Sketch: The copy layout tone is narrow,
First Aid Cabinet,Specialized Case & Box,Tool Bag ,
Dog Bath Tub,Metal Cabinet Co., Ltd. , http://www.nbbcabinet.com