2 Grasp the correct separation technology is the key
The image files obtained from scanners, digital cameras, and networks are usually in the RGB format. Before the output of the color separation film, the file needs to be converted into the CMYK format, which is the conversion of the color space. This step is the key to color separation processing. It should be based on different production processes, according to different printability of ink, paper, etc., set the dot gain value, gray balance parameters, black tone and choose a different color separation mode, only properly set these parameters, only It is possible to achieve high quality scanning separations.
1) Handle the contrast of the picture. Color reproduction is limited by the printability of paper and ink. High-grade coated paper prints can reproduce the highest density range of 1.8 to 1.9, and offset paper is even lower. For this reason, the gradation range of the manuscript must be compressed when copying, and it is inevitable that part of the gradation will be lost after the compression, so it is unlikely that the printed matter will completely reproduce the contrast effect of the high quality picture, especially the color reversal film. Copying can only make full use of the whiteness of the paper and the amount of four-color inks to achieve maximum print density contrast and visual contrast.
â— First, according to the density contrast and tone thickness of each original, determine the brightest (highlight or whitefield) and darkest (dark) as the starting and ending points of the tone setting, and try to match the original density range. Set the maximum dot value of the color separation sheet so that the print contrast is as close as possible to the contrast of the picture.
(2) The white field setting cannot be too peaceful. Taiping will make the high-gloss light of the printed product not gray; nor can it be too embarrassing, otherwise it will cause loss of the high-light level, as well as large signal noise and easy to produce coarse particles. a. The picture of the main tone, density contrast standard, extremely high light will not net, and the need for the level of highlight set as the basic white, that is, C4%, M2%, Y3%; b. , the color density of the picture is light, then the white field set the network value can be slightly larger, set the basic white at the brightest and most white place, in order to deepen the color tone level; c. to tone mainly, deep color density In the picture, the secondary highlight can be designated as a net, highlighting the brightness of the highlights and reducing (lightening) the midtones.
(3) The black market setting should not be too shallow or too shallow, which will make the darkness of printed products dark and not strong enough. It should not be too deep, too deep, which will make the printing products secretly dark, and the levels will be upgraded. a. Density contrast standard picture, to restore the copy, the black field settings should select the picture dark tone pure black parts, transmissive manuscript density is set to 2.70 ~ 3.00, the color photo density is set to 1.80 ~ 1.90. The basic black offset printing process is C90%~95%, M80%~85%, Y85%~90%, K75%~80%; b. The picture with small density contrast and light tone should be deepened, and the black field setting should be Select the second darkest part of the picture. The density of the transmitted manuscript is set to 2.30 to 2.50. Color photo density is set to 1.50 ~ 1.60, set the basic black; c. High density contrast, heavy tone, to reduce the light (light) copy, you can choose the darkest part of the picture, and increase the set density value, The density of the transmitted document is set to 3.00 to 3.50, the density of the color photograph is set to 2.00 to 2.30, and the basic black is set.
(4) The key to the success of dark copying lies in the correct black edition setting. a. The black site selection should try to choose the neutral black part of the black object to ensure the accuracy of the black version of the network value setting; b. The black version of the network value setting: the offset process should be 65% to 85% (offset Paper is printed at 65% to 70% and coated paper is printed at 75% to 85%. c. Effective use of the black plate is not only to add a black plate to the three primary colors, but to reduce the amount of ink for the three primary colors in the black portion, so that Increase the uniform black version, use the black version to open the tone level, and increase the contrast of the original. General removal of 20%, remove the color plate network value is C78%, M68%, Y68%, K90%; d. The starting point of the black plate is extended to 35% to 40% of the C plate at the small spot, then the picture can be increased. Medium and dark tone levels and three-dimensional sense, of course, the black version of the tone extended, the color part will be deepened, we must pay attention to the necessary lightening.
2) Handle white and black in color pictures. The white and black colors in the color picture are not only the important colors in the picture, but also have a black and white tone, which makes the color appear pure and pure. No matter how bright "white" is, or how dark the "black" is, it has a certain color tendency, but on the concrete picture, there may be exaggerated white and exaggerated black. Therefore, we must pay attention to the black-and-white tone processing in color images when we copy.
â— Various white objects in color photography pictures, such as: white clouds, white flowers, white porcelain, etc., have different texture characteristics and should be different when setting adjustments. Brightness should be 2% to 3% of the C version, M, Y version is not a net, usually 1% to 2%.
(2) The white objects of many current printed products often exhibit color cast and dew, which is due to the lack of awareness of gray balance among some operators. For high-gloss white objects that require a level, set the gray balance point value ratio, such as C5%~6%, M3%~4%, Y3%~4%. Such as white warm, three-color version of the dot value can also be close to the ratio, but must not lack a color version, otherwise it will be color cast, dew.
(3) Black objects in color photographs often cause haze due to environmental influences. When processing, first understand the adjustment of texture characteristics of various black objects, such as black steel, black leather clothing, black hair, etc., and their texture characteristics are different, and adjustments should be different. Such as black steel metal objects, to express its sense of weight, the setting should be based on the black version, outlet value up to 90%, while the three primary colors for the right amount removed, the sum of the four-color version is about 320%. As for the black leather clothing and Other objects, it mainly displays its smooth and delicate light texture. When scanning, the four-color version must be soft and delicate, and the contrast should not be too large. The sharpness should not be over-emphasized.
In actual production, the black color of the object is not pure due to the dark color of the photographic image. It should be noted that the three-primary version achieves the effect of neutral black, and then the black version is dominant, so as to achieve a pure black effect and better express the texture level of the black object.
(4) The dark tone of the artistic art picture is an important part of the image modeling art. The black color of the picture art is varied due to the different features and styles of various paintings. The scan setting should be handled differently. For example, the Chinese painting is mainly based on ink. Pure ink, so that the entire picture layer is rich, long tone black version up to 95% ~ 98%. The color ink paintings, whether heavy or light colored, should reach 90%-95% black, 65%-70% green, 55%-60% red and yellow, and a total of four colors ranging from 270% to 285%.
3) Handle people's skin color. There are many problems with the reproduction quality of portrait images in many books, advertisements, and albums. For example:
â— Some skin colors are seriously distorted, and some of the face color has become orange, red brown, and some have become blue, gray and black.
â— Some skin color is rough, hard and disjointed, there is no continuous transition between light, medium and dark tone, causing the dark part to reverse, yellow, red version shallow, forming a deep black version.
In addition to some of the original document itself, it is mainly due to the improper setting of scanning separation parameters and improper color processing. The general solution is:
a. Determine the tone of the skin tone. When performing character scanning and color separation, we must deal with the characteristics of various people's skin color. First, determine the tone of the skin color by its age, gender, occupation, origin, ethnicity and other characteristics. For example, female skin color should be white and delicate, delicate and ruddy. Only when the key tone is correct, there will be no large color distortion; b. Control the skin color of the dark part is not reddish. The dark tone of most manuscripts is set by the black field. The Y and M color plates are darker, and the dot value reaches about 85%, sometimes reaching 90%. The C color version has a color-dyeing effect on the red tea color, which tends to be too large. Therefore, for a darker skin tone with a larger area, it is necessary to pay attention to controlling the Y, M version below 80%, generally 75% ~ 78%, C color version slightly deepened, while the K version of the tone slightly extended to Make up for the inadequacy of the C version; c. Grasp the continuous transition tone of skin color. Should be able to grasp the facial skin tone from the bright part to the tone part to the dark tone part of the tone should have a continuous transition, can not be hard disjointed, especially the M color version of the tone to be soft coordination; d. Under normal circumstances, the yellow version of the high light calibration To stay in the red version, the middle face of the skin tone should be controlled below 50%, and the black and blue plates should be moderately controlled to keep the warm tone.
(to be continued)
The image files obtained from scanners, digital cameras, and networks are usually in the RGB format. Before the output of the color separation film, the file needs to be converted into the CMYK format, which is the conversion of the color space. This step is the key to color separation processing. It should be based on different production processes, according to different printability of ink, paper, etc., set the dot gain value, gray balance parameters, black tone and choose a different color separation mode, only properly set these parameters, only It is possible to achieve high quality scanning separations.
1) Handle the contrast of the picture. Color reproduction is limited by the printability of paper and ink. High-grade coated paper prints can reproduce the highest density range of 1.8 to 1.9, and offset paper is even lower. For this reason, the gradation range of the manuscript must be compressed when copying, and it is inevitable that part of the gradation will be lost after the compression, so it is unlikely that the printed matter will completely reproduce the contrast effect of the high quality picture, especially the color reversal film. Copying can only make full use of the whiteness of the paper and the amount of four-color inks to achieve maximum print density contrast and visual contrast.
â— First, according to the density contrast and tone thickness of each original, determine the brightest (highlight or whitefield) and darkest (dark) as the starting and ending points of the tone setting, and try to match the original density range. Set the maximum dot value of the color separation sheet so that the print contrast is as close as possible to the contrast of the picture.
(2) The white field setting cannot be too peaceful. Taiping will make the high-gloss light of the printed product not gray; nor can it be too embarrassing, otherwise it will cause loss of the high-light level, as well as large signal noise and easy to produce coarse particles. a. The picture of the main tone, density contrast standard, extremely high light will not net, and the need for the level of highlight set as the basic white, that is, C4%, M2%, Y3%; b. , the color density of the picture is light, then the white field set the network value can be slightly larger, set the basic white at the brightest and most white place, in order to deepen the color tone level; c. to tone mainly, deep color density In the picture, the secondary highlight can be designated as a net, highlighting the brightness of the highlights and reducing (lightening) the midtones.
(3) The black market setting should not be too shallow or too shallow, which will make the darkness of printed products dark and not strong enough. It should not be too deep, too deep, which will make the printing products secretly dark, and the levels will be upgraded. a. Density contrast standard picture, to restore the copy, the black field settings should select the picture dark tone pure black parts, transmissive manuscript density is set to 2.70 ~ 3.00, the color photo density is set to 1.80 ~ 1.90. The basic black offset printing process is C90%~95%, M80%~85%, Y85%~90%, K75%~80%; b. The picture with small density contrast and light tone should be deepened, and the black field setting should be Select the second darkest part of the picture. The density of the transmitted manuscript is set to 2.30 to 2.50. Color photo density is set to 1.50 ~ 1.60, set the basic black; c. High density contrast, heavy tone, to reduce the light (light) copy, you can choose the darkest part of the picture, and increase the set density value, The density of the transmitted document is set to 3.00 to 3.50, the density of the color photograph is set to 2.00 to 2.30, and the basic black is set.
(4) The key to the success of dark copying lies in the correct black edition setting. a. The black site selection should try to choose the neutral black part of the black object to ensure the accuracy of the black version of the network value setting; b. The black version of the network value setting: the offset process should be 65% to 85% (offset Paper is printed at 65% to 70% and coated paper is printed at 75% to 85%. c. Effective use of the black plate is not only to add a black plate to the three primary colors, but to reduce the amount of ink for the three primary colors in the black portion, so that Increase the uniform black version, use the black version to open the tone level, and increase the contrast of the original. General removal of 20%, remove the color plate network value is C78%, M68%, Y68%, K90%; d. The starting point of the black plate is extended to 35% to 40% of the C plate at the small spot, then the picture can be increased. Medium and dark tone levels and three-dimensional sense, of course, the black version of the tone extended, the color part will be deepened, we must pay attention to the necessary lightening.
2) Handle white and black in color pictures. The white and black colors in the color picture are not only the important colors in the picture, but also have a black and white tone, which makes the color appear pure and pure. No matter how bright "white" is, or how dark the "black" is, it has a certain color tendency, but on the concrete picture, there may be exaggerated white and exaggerated black. Therefore, we must pay attention to the black-and-white tone processing in color images when we copy.
â— Various white objects in color photography pictures, such as: white clouds, white flowers, white porcelain, etc., have different texture characteristics and should be different when setting adjustments. Brightness should be 2% to 3% of the C version, M, Y version is not a net, usually 1% to 2%.
(2) The white objects of many current printed products often exhibit color cast and dew, which is due to the lack of awareness of gray balance among some operators. For high-gloss white objects that require a level, set the gray balance point value ratio, such as C5%~6%, M3%~4%, Y3%~4%. Such as white warm, three-color version of the dot value can also be close to the ratio, but must not lack a color version, otherwise it will be color cast, dew.
(3) Black objects in color photographs often cause haze due to environmental influences. When processing, first understand the adjustment of texture characteristics of various black objects, such as black steel, black leather clothing, black hair, etc., and their texture characteristics are different, and adjustments should be different. Such as black steel metal objects, to express its sense of weight, the setting should be based on the black version, outlet value up to 90%, while the three primary colors for the right amount removed, the sum of the four-color version is about 320%. As for the black leather clothing and Other objects, it mainly displays its smooth and delicate light texture. When scanning, the four-color version must be soft and delicate, and the contrast should not be too large. The sharpness should not be over-emphasized.
In actual production, the black color of the object is not pure due to the dark color of the photographic image. It should be noted that the three-primary version achieves the effect of neutral black, and then the black version is dominant, so as to achieve a pure black effect and better express the texture level of the black object.
(4) The dark tone of the artistic art picture is an important part of the image modeling art. The black color of the picture art is varied due to the different features and styles of various paintings. The scan setting should be handled differently. For example, the Chinese painting is mainly based on ink. Pure ink, so that the entire picture layer is rich, long tone black version up to 95% ~ 98%. The color ink paintings, whether heavy or light colored, should reach 90%-95% black, 65%-70% green, 55%-60% red and yellow, and a total of four colors ranging from 270% to 285%.
3) Handle people's skin color. There are many problems with the reproduction quality of portrait images in many books, advertisements, and albums. For example:
â— Some skin colors are seriously distorted, and some of the face color has become orange, red brown, and some have become blue, gray and black.
â— Some skin color is rough, hard and disjointed, there is no continuous transition between light, medium and dark tone, causing the dark part to reverse, yellow, red version shallow, forming a deep black version.
In addition to some of the original document itself, it is mainly due to the improper setting of scanning separation parameters and improper color processing. The general solution is:
a. Determine the tone of the skin tone. When performing character scanning and color separation, we must deal with the characteristics of various people's skin color. First, determine the tone of the skin color by its age, gender, occupation, origin, ethnicity and other characteristics. For example, female skin color should be white and delicate, delicate and ruddy. Only when the key tone is correct, there will be no large color distortion; b. Control the skin color of the dark part is not reddish. The dark tone of most manuscripts is set by the black field. The Y and M color plates are darker, and the dot value reaches about 85%, sometimes reaching 90%. The C color version has a color-dyeing effect on the red tea color, which tends to be too large. Therefore, for a darker skin tone with a larger area, it is necessary to pay attention to controlling the Y, M version below 80%, generally 75% ~ 78%, C color version slightly deepened, while the K version of the tone slightly extended to Make up for the inadequacy of the C version; c. Grasp the continuous transition tone of skin color. Should be able to grasp the facial skin tone from the bright part to the tone part to the dark tone part of the tone should have a continuous transition, can not be hard disjointed, especially the M color version of the tone to be soft coordination; d. Under normal circumstances, the yellow version of the high light calibration To stay in the red version, the middle face of the skin tone should be controlled below 50%, and the black and blue plates should be moderately controlled to keep the warm tone.
(to be continued)
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