1. Black and white photo features
Black and white photographs were taken by photographers using the principles of plastic art and photography. The high-quality black-and-white photos should be rich in levels, with strong contrasts, dark dark tone, rich and soft tone, high-profile, thin, moist and white. However, the quality of the original manuscripts of the plates is not the same, and the ills of many photographs are difficult to overcome during the plate making process. Therefore, it is very important to make black and white photos full-text before separation. Such as adjusting the density of the original contrast, so that it meets the requirements of the plate shooting; Trimming tone is not complete, such as emphasizing dark tone, too much high-profile to be run out; repair some of the original image of the image of the defects; repair dirt, Make up for white spots, fill with coarse particles, etc.
2. Black and White Photo Plate Production Requirements
Photocopying of black-and-white photographs generally uses a direct screening process, using special hard SO films, gray contact screens to capture negative networks, and anti-Kaoyang network technology. Photographs with a film can not be achieved in three points to take into account the ideal black version of the replication level curve, so the black version of the film to shoot the main focus of the screen, the use of high-height mask on the shoulder to promote the top off the net, instead of the past Hand trimming, so that the high-profile level of natural expression. The toes use a dark mesh mask with no nets, and the layered exposure is applied when copying the sun nets so that the dark tone can be kept as much as possible.
Black-and-white photographs can be made into monochrome, two-color, and four-color versions. Most of the magazine illustrations use a black version. Most of the black and gray versions are used in the album. They are used to juxtapos the black and white drawings of the album, while the yellow, magenta, cyan, and black versions are used for printing. Color.
Monochrome plate making, black version uses long tone to reproduce the curve, dark tone calibration depth to 98%, partial coke black can be the field, high light point should be net. In order to strengthen the intermediate tone and dark tone, increase the dark tone level knob, make the dark tone curve steep to enhance the dark tone contrast, the middle tone curve straightened to meet the needs of monochrome plate making (the manuscript of the middle tone off the contrary is the case), such as See Figure 8-1-7. When printing, a certain amount of ink can also meet the overall requirements.
Two-color plate making, two-color printing using black ash, its purpose is to expand the reproduction density area. This means that in the possible range of highlights and shadows, the tone unique to the original is reproduced to the maximum.
The usual method is to decompose the main version (black version) and the sub-version (grey version), and the main version should be long when it is decomposed. The two editions are as follows:
Color version White field Black field
Black Edition 2%ï½ž3% 98%ï½ž100%
Gray version 3% 85%
The black version of the white field calibration shifts to the sub highlights, leaving the highlights out of network, the network area is slightly expanded, and the grey version of the high-light point non-enclosed network is slightly reduced to match. The deepest dark tone can be as deep as 98% to 100%. If there is a rich dark tone level, the black field calibration can be lighter. The black version should be used as a foiling role in the high-profile and talk-tuning convergence. The ash version has to play a role in enhancing the blackness in the darkest place, so that the dark tone can not be combined to distinguish the levels. There should also be a corresponding amount of color in the light and high tone.
The gray ink should not be light and shallow, but it can not play the above role, but it can not be as close as black, otherwise it will make the picture lack the feeling of moisture and luster, and it is easy to expose the obvious unsightlyness after overlapping. Ink can change the hue of gray (such as yellow, blue, etc.) according to customer requirements and photo tone needs. Ash density in the field should be changed from the usual 0.3-0.4 to 0.9, so that the copy can reach the quality of the original.
It should also be pointed out that copying of black-and-white photos, black and gray version must not be different only in depth of the layout and ink shades, and the different divisions of the various tones on each layout, simply relying on two overlapping printing, is not easy to get a good copy The effect. It is necessary to emphasize the different division of labor between the black and gray versions in order to make the originals at all levels more completely reproduce the printed products.
The four-color platemaking uses the principle of non-chromatic structure to print black and white photographs. It is a process that uses the black version as the main method, and uses the combination of the three primary colors to form a gray tone lining under the black ink to compensate for the lack of black ink.
In daily work, often encountered in a layout is mostly color pictures, which have one or two black and white photos. If only a single color plate is used, due to the poor quality of the black ink at the moment, the color of the printed product is thin, and it is incongruous with the surrounding color pictures. If black and gray two-tone plate making, tone effect will be better, but with the color version printing, four-color printing can not be completed at once. In this case, black and white photographs should be printed using a non-color structure. Its advantages are:
1 Hue is thick, strong in three-dimensional sense, rich in layers, and vividly reproduces the characteristics of the artwork. Makes prints bright and white, dark in darkness, resembling a black and white photo;
2 Because of the rich color, it can be coordinated with the surrounding color pictures.
Four-color version settings:
1 The dark tone of the black version is long and full. Extremely high light does not require a high level of light modulation, and its network is 1% to 2%. The dark tone requires a hierarchy, the dots are made 85% to 90%, and the dark dots are 95% to 100%.
2 The yellow, magenta version of the ultra-high light network, high light tone of the network of 1% to 2%, dark tone 45%, the local depth of 50%.
Green copyright high light network, high light tone of the network 2% to 35%, dark tone of 60%, the local depth of 65%. The tricolor version started to produce high light spots (Y, M2%, C3%) at 15% to 30% of the black plate. The sum of the dot areas of the dark four-tone version is 270% to 280%, which can achieve the full black effect (as shown in Figure 8-1-8).
The above is the setting data of the standard manuscript. If the manuscript with a density contrast is too large or too small, the setting data can be changed.