The role of the hottest black version in color rep

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The role of black plate in color reproduction

the main reason for the use of black in color reproduction is that the Y, m and C inks we used in printing are not pure and can not superimpose saturated black. Adding black version in color reproduction can improve the outline level and detail contrast of dark areas

black version can be sent as short tone black version, medium tone black version and long tone black version. Short tone black version, also known as skeleton black version and outline black version, mainly reflects the dark tone level of the original, strengthens the picture contrast and stabilizes the color. Middle note black is a linear black version, which is suitable for originals with color and achromatic, such as scenery, gray buildings, etc. The long tone black version refers to the black version generated by the principle of the ground color detachment, which has a large reproduction range and is suitable for the original manuscript with color elimination as the main color, for example, the traditional Chinese painting with black as the main color

with the progress of modern printing technology and equipment, the printing speed of the printing machine is faster and faster, the drying time of the ink becomes shorter, and the printing changes from wet pressing to wet pressing. Therefore, it is necessary to complete color reproduction with less ink. For this reason, there is a reproduction process that uses black ink to replace part or all of the color ink, i.e. achromatic structure. This reproduction process can not only ensure the high quality of image reproduction, but also expand the role of the background color detachment and the black version to the whole tone range

I. generation of black version in Photoshop

the color desktop publishing system is different from the electric extension when handling black version. It has separate black version setting and black version adjustment functions. According to the needs of copying, you can arbitrarily adjust multiple parameters in the generation of black version, adjust the curve shape of black version, and determine the starting point, ending point and maximum point value of black version. The high-speed range is large and the range is wide, which can meet the requirements of Black Edition for all kinds of original copy. For example, the separation setup in Photoshop software involves the non color structure technology

open the separation setup dialog box. You can select color settings from the file menu to open its sub list and select the separation setup command. In the dialog box, GCR is gray component substitution and UCR is background color removal. People can choose one of them as a way to use black ink reasonably in color separation

generally speaking, UCR method can be selected for color separation when printing on non coated paper or paper. GCR is the default option for color separation mode when printing coated paper. When using gray component substitution technology, more black inks will be used in a wide range of color gamut. Compared with UCR color separation, GCR color separation tends to reproduce dark and saturated colors, and can better maintain gray balance during image printing or printing

1. black version generation setting

black version generation cikoni (Stuttgart, Germany) composite materials company first designed the structure of carbon fiber composite (black generation) through combination and fully automated manufacturing methods to determine how much black ink is used in UCR or GCR for background color removal or gray component replacement

for GCR color separation, users need to select the degree of black version generation, ink volume limit and specified background color gain. In the interval setup dialog box, you can choose from several black versions

1) the mdium option is the default option of the system. In most cases, satisfactory results can be obtained. The light and heavy options in the dialog box allow users to slightly reduce or increase the effect of medium settings

2) the none option does not generate a black version during color separation

3) the maximum option maps the gray value directly to the black version generated value. This option is used for images with a large number of black fields on a bright background

4) the custom option allows users to manually adjust the black version to generate curves

2. use the custom black version option

1) select a black version generation surface from light, medium, heavy or maximum to get a black version generation curve, which is used as the starting point of custom black version

2) select custom from the black generation list to open its dialog box

3) place the cursor on the curve and drag the mouse to adjust the black curve. When adjusting the black version curve, the green version curve and magenta yellow version curve will be automatically adjusted due to the change of the black version curve and the total ink amount

3. black ink limit

whether it is UCR color separation or GCR color separation, the ink limit value entered in the separation setup dialog box is used when generating a black version. The total ink volume limit is the maximum ink density that can be supported. By default, the limit for black ink is 100% and the total ink limit is 300%. It is necessary to check with the printer to confirm whether these values should be adjusted

black ink limit gives black ink an upper limit. For example, if 50% of the black component is obtained without background color removal or gray component substitution for color separation, and if the black ink is limited to 70%, the maximum background color removal is 20%

4. total ink limit

total ink limit limits the total amount of ink used during printing. If the amount of original cyan ink is 90%, magenta ink is 87%, tribute ink is 85%, black ink is 7%, and the total amount of original ink is 332%; If the total amount of ink is limited to 302%, 20% of the background color can be removed

5. base color gain

separation setup dialog box, the base color gain (UCA) option is used to increase the ink after removing the amount of black ink in the dark tone area. Its function is opposite to that of base color removal. It is to increase the amount of color ink in the dark tone area. It is the same as UCR. For those areas that will show flat black if printed with black ink only, UCA will produce rich dark tones

UCA amount gives the same percentage content as that of background removal. During color separation, Photoshop will use hydrogen bonds to increase the amount of color ink in dark areas. Increasing the base color gain increases the amount of C, m and Y ink to be removed. The ink range can be set to 0% - 100%, which can be checked with the printing three to obtain the optimal value. If you can't confirm the value, you should keep it. When ordering the tensile testing machine, you should communicate with the manufacturer's technical department 0% in advance

II. The role of black printing plate in color reproduction

after long-term practice, people generally believe that the role of black printing plate in color reproduction has the following points:

1. it improves the stability of gray balance.

y, m and C primary color inks are difficult to achieve neutral gray balance. After the background color removal process is adopted, the neutral gray balance is basically not affected by the amount of color ink, and the neutral gray reproduction is mainly realized by black ink. Therefore, grey balance is easy to realize

2. increased the density and contrast of the printed matter

according to the current conventional conditions, the density of Y, m and C inks after printing is 1 7. The ability of people's vision to distinguish dark tone can reach 1 9。 Therefore, the black version can enhance the light absorption capacity of the paper, the light absorption rate can be increased from 96% to 98%, the density will be increased accordingly, the step will be extended, the picture alignment will be improved, the stereoscopic and spatial sense of the image will be enhanced, and the picture will become lifelike

3. enhanced the level from middle tone to dark tone

in the color reproduction process, the law of tone reproduction is that the level of bright tone area is maintained and emphasized, and the level of middle tone area is maintained or slightly compressed. At present, the emphasis of black version tone performance is generally from the middle to the dark tone area, which makes the dark tone area prominent, improves the visual effect of the picture, and especially meets people's visual requirements for words. Color reproduction needs both pictures and texts. From the visual requirements, black text has the best effect and is easy to read

4. the printing adaptability is expanded and the printing cost is reduced.

black ink can be considered as C, m, Y color ink. Therefore, some or all of the three primary color printing ink can be removed from a certain part of the picture and replaced with black ink, which can not only meet the color requirements of the image, but also reduce the ink consumption and reduce the printing cost. Similarly, the density of black ink is higher than that of other color printing inks. In the mixed color area, black ink is used to replace the three color inks. The total amount of printing ink is reduced, which not only avoids the accumulation of ink layer in the dark area, but also accelerates the drying speed of printing ink, reduces the phenomenon of dirt, improves the printing adaptability, and meets the requirements of high-speed, multi-color wet press printing

in a word, the existence of black plates is the requirement of the objective conditions of printing. Today, when the ink can not meet the ideal requirements and printing is still dominated by pressure printing, the production process of black plates will be improved with the development of printing industry for a long time

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