First, the meaning of black and the range of black solid density in printing
"Color is a general term for achromatic and colored." Achromatic refers to the series of white to black in printing. The actual contrast between the maximum whiteness of printing paper and the effective density of yellow, magenta, cyan and black solid ink layers, namely the whiteness, light gray, medium gray, dark gray, black, and sometimes Used to black concept.
In the non-colored series, the ideal white is a fully reflective object, there is no 100% reflective object in life, the best coated paper has a reflectance of about 90% for printing paper, only 50% for newsprint, and other printing paper ( Offset paper, letterpress paper, and dictionary paper are between the two; the ideal black is an object that completely absorbs the visible spectrum, and the completely absorbed object does not exist, and is printed on a coated paper, and the effective density of the four colors superimposed is about 1.8. The general newsprint is printed in monochrome, the black density is in the range of 1.0 to 1.2, the offset paper is printed in monochrome, and the black density is in the range of 1.2 to 1.4. The black density of the coated paper is 1.4 to 1.8. Therefore, it can be said that the black density is between 1.0 and 1.8.
Second, the role of the black version in color reproduction
1, using the black version can enhance the density of the image contrast. According to the current conventional conditions, the effective density of yellow, magenta, and blue primary inks after superimposition is about 1.8 at maximum, and the visual resolution capability can be achieved at 1.8 to 2.0. Therefore, the black version of the appropriate tone is used to enlarge the paper. Absorption capacity, the general absorption increased from 96% to 98%, that is, the actual increase of 0.2 to 0.4 effective density, thereby increasing the overall image density contrast range, enhance the three-dimensional image, sense of space, improve product quality.
2, black version can stabilize the color of the image. The range of stability depends on the length of the black tone, and the longer the tone of the black version, the greater the range of stable colors. In general, most color-dominated images use skeleton black editions, mainly for stabilizing dark colors and enhancing image outlines. The specific implementation needs to analyze the characteristics of image color and tone to determine the starting point and curve characteristics of the blacktone tone. The tone of the black version of Chinese-style Chinese paintings and neutral-toned images should be relatively long. However, in addition, the dark tone is longer and the tone of the image is likely to become darker. At present, the image platemaking software has the function of automatically generating black editions. If the original hue is standard, the result of color separation and screening is generally in line with reality. The problem is that the proportion of manuscripts used for making plates meets the standards is very small, and the color separation and screening Most of the time when adjustments are made, the color version is generally more important, and the black version is ignored. The starting point and the gamma value of the blacktone tone should be adjusted according to the characteristics of the manuscript and the printability conditions.
In general speaking, the deviation of the bright medium tone color can be adjusted by adjusting the size of the dot area, and the dark tone of the image, especially 75% by the dot area, is restricted by the dot area adjustment, and therefore a considerable amount of print-to-dark tone Unstable. From the results of a number of printing products tested in Beijing (with the same paper, the same ink, the same control strip), no one is the ideal neutral ink, most of them are measured with the green filter, the purple blue filter Secondly, the measured value of the red filter is low, which indicates that the image is darker in color, but in reality, most images are cooler in color. Therefore, the use of a blacktone overlay of an appropriate tone can play a role in stabilizing the medium-to-dark tone, overcoming the problem of darker tone and achieving satisfactory results.
"Color is a general term for achromatic and colored." Achromatic refers to the series of white to black in printing. The actual contrast between the maximum whiteness of printing paper and the effective density of yellow, magenta, cyan and black solid ink layers, namely the whiteness, light gray, medium gray, dark gray, black, and sometimes Used to black concept.
In the non-colored series, the ideal white is a fully reflective object, there is no 100% reflective object in life, the best coated paper has a reflectance of about 90% for printing paper, only 50% for newsprint, and other printing paper ( Offset paper, letterpress paper, and dictionary paper are between the two; the ideal black is an object that completely absorbs the visible spectrum, and the completely absorbed object does not exist, and is printed on a coated paper, and the effective density of the four colors superimposed is about 1.8. The general newsprint is printed in monochrome, the black density is in the range of 1.0 to 1.2, the offset paper is printed in monochrome, and the black density is in the range of 1.2 to 1.4. The black density of the coated paper is 1.4 to 1.8. Therefore, it can be said that the black density is between 1.0 and 1.8.
Second, the role of the black version in color reproduction
1, using the black version can enhance the density of the image contrast. According to the current conventional conditions, the effective density of yellow, magenta, and blue primary inks after superimposition is about 1.8 at maximum, and the visual resolution capability can be achieved at 1.8 to 2.0. Therefore, the black version of the appropriate tone is used to enlarge the paper. Absorption capacity, the general absorption increased from 96% to 98%, that is, the actual increase of 0.2 to 0.4 effective density, thereby increasing the overall image density contrast range, enhance the three-dimensional image, sense of space, improve product quality.
2, black version can stabilize the color of the image. The range of stability depends on the length of the black tone, and the longer the tone of the black version, the greater the range of stable colors. In general, most color-dominated images use skeleton black editions, mainly for stabilizing dark colors and enhancing image outlines. The specific implementation needs to analyze the characteristics of image color and tone to determine the starting point and curve characteristics of the blacktone tone. The tone of the black version of Chinese-style Chinese paintings and neutral-toned images should be relatively long. However, in addition, the dark tone is longer and the tone of the image is likely to become darker. At present, the image platemaking software has the function of automatically generating black editions. If the original hue is standard, the result of color separation and screening is generally in line with reality. The problem is that the proportion of manuscripts used for making plates meets the standards is very small, and the color separation and screening Most of the time when adjustments are made, the color version is generally more important, and the black version is ignored. The starting point and the gamma value of the blacktone tone should be adjusted according to the characteristics of the manuscript and the printability conditions.
In general speaking, the deviation of the bright medium tone color can be adjusted by adjusting the size of the dot area, and the dark tone of the image, especially 75% by the dot area, is restricted by the dot area adjustment, and therefore a considerable amount of print-to-dark tone Unstable. From the results of a number of printing products tested in Beijing (with the same paper, the same ink, the same control strip), no one is the ideal neutral ink, most of them are measured with the green filter, the purple blue filter Secondly, the measured value of the red filter is low, which indicates that the image is darker in color, but in reality, most images are cooler in color. Therefore, the use of a blacktone overlay of an appropriate tone can play a role in stabilizing the medium-to-dark tone, overcoming the problem of darker tone and achieving satisfactory results.
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